No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Successful recovery of North Island kokako Callaeas cinerea wilsoni populations, by adaptive management
Abstract
Kokako Callaeas cinerea wilsoni (Callaeidae) populations are declining in unmanaged primary forests of the North Island, New Zealand. An 8-year experiment to determine the cause of decline was undertaken by controlling introduced browsing and predatory mammal pests in two forest areas, then monitoring pest abundance, kokako chick output and adult density in the managed forests and an unmanaged non-treatment block. Treatments were switched between the unmanaged and one of the managed areas after 3–4 years. Reduction of pests, especially brushtail possums Trichosurus vulpecula and ship rats Rattus rattus, to very low levels resulted in significant increases in kokako chick output and adult density in all three study populations. This was due primarily to increased success of nesting attempts, which then increased the number of pairs attempting to breed, initially as newly recruited young females formed pairs with residual single males. The `adaptive management' approach of using routine large-scale pest control in a co-ordinated experiment to directly test the pest-limitation hypothesis enabled researchers and managers to investigate the cause of decline and to increase populations simultaneously. Predation is a more immediate cause of current kokako declines than competition. Management to recover vulnerable kokako populations should aim to reduce possums and ship rats to very low levels (<1% trap catch for possums; <1% tracking rate for ship rats, using particular indexing techniques) at the onset of the kokako nesting season, for several consecutive years.
... As described above, in cooler beech forests, black rats are generally scarce but occasionally eruptive to very high density, while in warmer podocarp-broadleaved forests, they are nearly always abundant (Walker et al. 2019 Footprint tracking tunnels are frequently used in NZ as a standard protocol (Gillies & Williams 2013) to derive indices of black rat and mouse abundance that can be used as target measures for residual (post-control) pest abundance. This target is usually 5% tracking rate (Innes et al. 1999;Elliott & Kemp 2016) but up to ≈15% residual rat tracking rate can be beneficial (Armstrong et al. 2006;Binny et al. 2021). Aerial 1080 with at least one prefeed is generally effective in that it reduces black rats to 5% tracking rate or lower in most (but not all) operations. ...
... Unfenced ecosanctuaries were first established by DOC staff during 1995−96, spurred by the success of some experimental mainland species restoration programs (e.g. Innes et al. 1999;Moorhouse et al. 2003). These early sites (then called "mainland islands") have unique historical roles in NZ conservation because in the following decades they undertook and documented many experimental pest control trials (Saunders & Norton 2001;Gillies et al. 2003;Binny et al. 2021). ...
... Managing multiple pests at a site minimizes unwanted population increases due to removal of a predator or competitor and yields more diverse ecological gains. Black rat control has contributed to documented increases of North I. kokako (Innes et al. 1999 Gillies et al. 2003). ...
Aotearoa - New Zealand has only four rodent species, all introduced. In order of arrival, they are Pacific rat Rattus exulans Peale, brown rat R. norvegicus Berkenhout, house mouse Mus musculus Linnaeus, and black rat R. rattus Linnaeus. Rodent management in New Zealand aims mainly to conserve indigenous biodiversity rather than to protect crops or manage diseases, as is usual elsewhere. We describe four major 'regimes' and one major vision for rodent control in New Zealand to meet ecological restoration objectives. Current challenges for island eradications are for large islands that are remote or populated by people. Aerial 1080 is the only large-scale (tens of thousands of hectares) option for black rat control, but its application requires adjustment to counter subsequent rapid black rat repopulation. Unfenced 'ecosanctuaries' (up to 700 ha) use ground-based traps and poisons to target mainly black rats and face constant reinvasion. Ecosanctuaries with mammal-resistant fences (up to 3,500 ha) limit reinvasion and target more pest species and have enabled the return of previously extirpated taxa to the main islands. Predator Free 2050 aims to eradicate the rat species (but not mice) plus some other introduced mammals from New Zealand by 2050. This vision is not attainable with current tools, but research and experimental management is exploring techniques and technologies. The large scale (to 100 000 ha) at which black rats are now targeted for control to extremely low abundance seems to be unique to New Zealand. This article is protected by copyright. All rights reserved.
... Predator-suppression experiments are critical to the design of biodiversity conservation strategies, especially on islands that have been greatly affected by the introduction of mammalian predators (Simberloff 1995;Courchamp et al. 2003). Although individual bird species that benefit from predator suppression receive most research attention (e.g., Innes et al. 1999;Glen et al. 2012), the broader consequences of predator suppression on avifauna are less understood. Some species may benefit more than others and some may even be disadvantaged because, for example, the predators no longer suppress their competitors and thus a decline in densities of the subordinate species results (Mountainspring & Scott 1985). ...
... In cases where the effects of invasive predators have been quantified, thresholds that signal the need for conservation action have been determined for a few New Zealand bird species. For example, effective protection of the Kokako (scientific names of bird species are in Table 1), a large endemic species, requires standardized abundance indices of ship rats and possums to be maintained below 1% (Innes et al. 1999). A negative relationship between nest success and ship rat abundance has been demonstrated for 2 small endemics, the North Island Robin (Armstrong et al. 2006) and the North Island Fantail (Fea & Hartley 2018). ...
... Although we had limited sample sizes for these species in our study, previous work demonstrates the vulnerability of these species to predation from introduced mammals (O'Donnell 1996; Innes et al. 1999;Basse et al. 2003;Dilks et al. 2003;Hooson & Jamieson 2003;Taylor et al. 2005;Toy et al. 2018), and these species have been brought close to extinction on New Zealand's mainland since the introduction of mammalian predators. The absence of these deeply endemic species across many sites in our meta-analysis-weakened our results because these species likely had the most negative responses at sites lacking mammal control and the most positive responses to high-intensity mammal control. ...
Over the past 1000 years New Zealand has lost 40–50% of its bird species, and over half of these extinctions are attributable to predation by introduced mammals. Populations of many extant forest bird species continue to be depredated by mammals, especially rats, possums, and mustelids. The management history of New Zealand's forests over the past 50 years presents a unique opportunity because a varied program of mammalian predator control has created a replicated management experiment. We conducted a meta‐analysis of population‐level responses of forest birds to different levels of mammal control recorded across New Zealand. We collected data from 32 uniquely treated sites and 20 extant bird species representing a total of 247 population responses to 3 intensities of invasive mammal control (zero, low, and high). The treatments varied from eradication of invasive mammals via ground‐based techniques to periodic suppression of mammals via aerially sown toxin. We modeled population‐level responses of birds according to key life history attributes to determine the biological processes that influence species’ responses to management. Large endemic species, such as the Kaka (Nestor meridionalis) and New Zealand Pigeon (Hemiphaga novaeseelandiae), responded positively at the population level to mammal control in 61 of 77 cases for species ≥20 g compared with 31 positive responses from 78 cases for species <20 g. The Fantail (Rhipidura fuliginosa) and Grey Warbler (Gerygone igata), both shallow endemic species, and 4 nonendemic species (Blackbird [Turdus merula], Chaffinch [Fringilla coelebs], Dunnock [Prunella modularis], and Silvereye [Zosterops lateralis]) that arrived in New Zealand in the last 200 years tended to have slight negative or neutral responses to mammal control (59 of 77 cases). Our results suggest that large, deeply endemic forest birds, especially cavity nesters, are most at risk of further decline in the absence of mammal control and, conversely suggest that 6 species apparently tolerate the presence of invasive mammals and may be sensitive to competition from larger endemic birds.
... In particular, negative impacts on bird abundance and diversity are well recognised (King 1984). Significant conservation gains have been made through landscape scale predator control for numerous avian species (Innes et al. 1999;Innes et al. 2010;Whitehead et al. 2010;Robertson et al. 2019). However, the impacts of mammalian predators on other native fauna, including herpetofauna, and our ability to use standard predator control methods to recover their populations, is relatively poorly understood and developed. ...
... The management threshold set for continuous suppression of rats within the treatment area was a mean rat tracking index of < 10%. This was based on knowledge, at the time, of rodent suppression for bird conservation in similar North Island forests (Innes et al. 1999) and therefore considered an achievable threshold that should provide protection to the frog population. A threshold tracking index was not set for mice. ...
... Large-scale predation control on the mainland, principally targeting possums, mustelids and rats, began in the late 1990s, focussing on in situ conservation of a range of bird species including North Island kōkako and brown kiwi, mōhua, and kākā (Innes et al. 2019). For example, work on kōkako pioneered the use of infrared cameras to identify the role of possums as predators, and demonstrated the feasibility of controlling possums, mustelids and rats to sufficiently low numbers and at large enough spatial scales to enable recovery of a remnant population at Mapara in the central North Island (Innes et al. 1999). These advances prompted DOC's establishment of six 'mainland island' sites, where intensive control of most or all introduced mammals in unfenced areas of up to 6000 ha delivered measurable gains for indigenous taxa (Saunders & Norton 2001). ...
... Subsequent funding pressures and premature optimism about the apparent success of the TB programme saw a reduction in possum control operations in the early 1980s, resulting in a rapid rebound in both possum abundance and TB prevalence . Renewed commitment to the goal of TB elimination from livestock herds, coupled with recognition of the role of possums as a predator of indigenous taxa (Innes et al. 1999), saw further expansion of possum control operations through the late 1980s and 1990s. Sustained control continues today, but over everdiminishing areas as TB is progressively eliminated. ...
... The swamp harrier (Circus approximans Peale 1848) is a common raptor species through Australia, New Zealand, and the south west Pacific including Vanuatu, New Caledonia, and Fiji (Watling 2001). This diurnal hunter mostly searches for prey by slow-quartering, and attack prey by dropping or diving (Baker-Gabb 1984a, 1984b, often over lower vegetation (Marchant & Higgins 1993), but also over tall primary forest (Innes et al. 1999). Live prey items vary in size, from small Carabid beetles and grasshoppers to birds and mammals >300 g (Douglas 1970;Marchant & Higgins 1993). ...
... A pair exclusively eating crested iguanas would presumably consume about 200 g of iguana each day, which equates to one average sized iguana (218 g) per day. Based on average body-mass for Fijian crested iguana, the 63 In New Zealand it has been suggested that control of harriers might be warranted to assist the reestablishment of a threatened forest bird species (Innes et al. 1999). The fact that only one pair of harriers is likely to use Yadua Taba makes it unlikely that predation is a threat to that population of crested iguanas, especially since the iguana population is probably at or near carrying capacity. ...
The Fijian crested iguana (Brachylophus vitiensis) is the largest extant lizard in Fiji, where it enjoys life in the absence of any mammalian predators. On the only island where this iguana is abundant, the only predator appears to be the swamp harrier (Circus approximans), which is non‐selective in its iguana prey, catching individuals in a similar proportion to their size availability. Here we report on the first observation of a reptile being the major prey item of the swamp harrier.
... Where vegetation type and cover are adequate, local populations of New Zealand forest birds are limited primarily by predation at nests by introduced predatory mammals (Innes et al. 2010). In these situations, native bird populations frequently recover after control measures reduce pest predator densities (Innes et al. 1999;Moorhouse et al. 2003;Armstrong et al. 2006;Innes et al. 2010;Miskelly 2018;Binny et al. 2021), and tūī are among the most responsive species to such control (Graham et al. 2013;Miskelly 2018;Fitzgerald et al. 2019). ...
... Our work has not substantially clarified targets of residual abundance for key nest predators (ship rats and possums) for tūī, but the mean post-control ship rat tracking index of 2.7% and mean postcontrol possum residual trap catch index of 1.2% achieved by Halo contractors appear to be adequate to recover tūī numbers in this context. This response is consistent with levels of residual abundance (<5% by each measure) recommended for recovery of North Island kōkako (Callaeas wilsoni; Innes et al. 1999), kererū (Hemiphaga novaeseelandiae; Innes et al. 2004), and North Island robin (Petroica longipes; Armstrong et al. 2006). ...
Public and our observations during 1999-2004 suggested that tūī (Prosthemadera novaeseelandiae) visited the city of Hamilton during March to October only, outside the nesting season. From 2004 onwards, we captured and banded 51 adult tūī and fitted radio transmitters to 41 in Waikato urban areas to locate nests. We directly observed 15 nests to determine nesting success and gather evidence of any predation events. Tūī moved 5-23 km from urban areas to surrounding native forests at the onset of nesting, but only four (29%) of 14 unmanaged nests fledged young, due mostly to predation by ship rats (Rattus rattus), swamp harriers (Circus approximans), and brushtail possums (Trichosurus vulpecula). Subsequent effective pest mammal control in forests around Hamilton was associated with greatly increased year-round tūī abundance and nesting in Hamilton. These results confirm previous findings that tūī move widely in winter; that they readily cross pasture in the absence of forest corridors, and that they will permanently inhabit urban areas. Provided adequate food is available, effective control of ship rats and possums can rapidly (1-4 years) increase tūī visits and nesting within 20 km of managed sites, enabling recolonisation of proximate urban habitats by this iconic endemic taxon, despite previous evidence for natal philopatry. Fitzgerald, N.; Innes, J.; Watts, C.; Thornburrow, D.; Bartlam, S.; Collins, K.; Byers, D.; Burns, B. 2021. Increasing urban abundance of tūī (Prosthemadera novaeseelandiae) by pest mammal control in surrounding forests. Notornis 68(2): 93-107.
... Ship rats, brushtail possums, and stoats are primary targets of control for most projects. However, relationships between residual pest abundance (i.e., the relative abundance of pests that remain after control) and corresponding biodiversity impacts remain a critical knowledge gap, except for a handful of native species (Innes et al. 1999. ...
... Our findings suggest that after approximately seven years of sustained control, competition (or other factors) is strong enough to drive declines in introduced avifauna. Other studies have examined vulnerability of select New Zealand bird species to the abundance of key mammalian predators (Innes et al. 1999, Armstrong et al. 2006, Elliott et al. 2010, Innes et al. 2010, Fea et al. 2020; however, this is the first attempt to explicitly quantify pest density-biodiversity impact relationships for whole endemicity subgroups. These findings guide managers by identifying threshold levels of residual pest abundance that should be achieved in order to observe a biodiversity benefit from control. ...
Invasions by alien pest species contribute heavily to global biodiversity decline, with invasive mammals having some of the greatest impacts on endemic biota. Pest management within ecological restorations is therefore critical for conserving threatened biota. Coordinating restoration efforts at global scale requires evidence of the relative efficacy of different pest‐managed restoration approaches (“regimes”) for enhancing biodiversity. Our national meta‐analysis of 447 biodiversity responses across 16 ecological restorations quantifies significant benefits for biodiversity over two decades and multiple trophic levels, and across a spectrum of invasive mammal suppression‐to‐eradication regimes. Deeply endemic species had the strongest responses to pest control compared with recent native or introduced biota. Using this information, we predict levels of pest suppression required to confer biodiversity benefits, to guide future management strategies. Our findings provide new evidence that invasive pest control is an effective approach to ecological restoration, to aid decision‐makers in setting objectives and making targeted investments.
... Invasive predators are controlled to protect native fauna in many parts of New Zealand (e.g. Innes et al. 1999;Reardon et al. 2012;Russell et al. 2015). However, predator control is usually in conservation reserves, wildlife sanctuaries or remnants of native habitat. ...
... One solution would be to apply a treatment reversal (e.g. Innes et al. 1999) in which the treatment and non-treatment areas are switched. However, stopping predator control in our current treatment area would be contrary to the aims of this conservation intervention. ...
Invasive predator control to protect native fauna usually takes place in native habitat. We investigated the effects of predator control across 6000 ha of multi-tenure, pastoral landscape in Hawke's Bay, North Island, New Zealand. Since 2011, low-cost predator control has been conducted using a network of kill traps for mustelids (Mustela spp.), and live trapping for feral cats (Felis catus). Although not deliberately targeted, other invasive mammals (particularly hedgehogs Erinaceus europaeus) were also trapped. We monitored predators and native prey in the predator-removal area and an adjacent non-treatment area. Predator populations were monitored using large tracking tunnels, which also detected native lizards. Invertebrates were monitored using artificial shelters (weta houses). Occupancy modelling showed that site use by cats and hedgehogs was significantly lower in the predator-removal area than in the non-treatment area. Site use by mustelids also appeared to be lower in the treatment area, although sample sizes were too small to allow firm conclusions. Site use by invasive rats (Rattus spp.) was higher in the treatment area, while that of house mice (Mus musculus) showed no difference between treatments. There was evidence of positive responses of some native biodiversity, with site use by native lizards increasing significantly in the treatment area, but not in the non-treatment area. Counts of native cockroaches were higher in the treatment area, but other invertebrates were detected in similar numbers in both areas. Our results show that low-cost predator control in a pastoral landscape can reduce invasive predator populations, with apparent benefits for some, but not all, native fauna.
... Hay et al. 1985;McLennan et al. 1996;Wilson et al. 1998). An important scientific conclusion was that these endemic bird species were long-lived but had poor juvenile recruitment because of mammal predation (McLennan et al. 1996;Innes et al. 1999;Kelly and Sullivan 2010), resulting in small, aging populations persisting for decades on the mainland, apparently co-existing with their agents of decline. ...
... In the 1990s, innovative attempts to recover taxa in situ in mainland forests with largescale pest control achieved some successes (e.g. mohua Mohoua ochrocephala, O'Donnell et al. 1996; North Island kōkako Callaeas wilsoni, Innes et al. 1999; kākā Nestor meridionalis, Moorhouse et al. 2003; North Island brown kiwi Apteryx mantelli, Robertson et al. 2011). This inspired Department of Conservation (DOC) staff to trial 'Mainland Islands' that used sustained trapping and poisoning to control key mammal pests at unfenced mainland sites. ...
We define an ecosanctuary in a New Zealand context as ‘a project larger than 25 ha implementing multi-species, pest mammal control for ecosystem recovery objectives, and with substantial community involvement’. We present attributes of 84 projects meeting this definition, including three lacustrine islands, 16 marine islands, seven ring-fenced ecosanctuaries, seven peninsula-fenced ecosanctuaries and 51 unfenced mainland ecosanctuaries. Ecosanctuaries have biological and social objectives, and some have returned threatened, previously extirpated taxa to the New Zealand mainland. Increasingly, these intensively managed sites are being embedded in human-altered landscapes with low levels of pest control – a ‘core and buffer’ system. Most community groups that establish ecosanctuaries lack the technical expertise, resources and mandate to undertake regional or national prioritisation. There is a strong need for agency leadership of this, and to develop best practice pest control, pest monitoring and biodiversity outcome monitoring tools, as goals for national restoration of biodiversity rapidly expand.
... Elliott & Kemp 2016). Positive effects of such management on survival and reproductive success have been measured for many species (O'Donnell et al. 1996;Innes et al. 1999Innes et al. , 2004Moorhouse et al. 2003;Powlesland et al. 2003;Whitehead et al. 2008;O'Donnell & Hoare 2012), but achieving good outcomes for birds is complicated by irruptive predator dynamics in New Zealand forests. These dynamics result from the dominance of massseeding (masting) plant species in New Zealand landscapes (Wardle 1984;Norton & Kelly 1988). ...
... Feral cat populations, normally present only on the periphery of large forest tracts when rodents are scarce, may expand into these forests from adjacent pastoral lands and braided river beds so as to become noticeable during the post-mast year. Brushtail possum (Trichosurus vulpecula), an additional predator and/ or competitor associated with bird population limitation (Innes et al. 1999(Innes et al. , 2004, potentially also responds to mast with higher productivity and survival (Sweetapple 2003), but intrinsic limitations on possum population growth prevent the high-magnitude irruptive spikes observed for rodents and stoats. New Zealand forest bird species vary in their susceptibility to these predators because of differences in bird size and behaviour (usually breeding behaviour), and the importance of birds in predator diets may change with rodent availability (Murphy et al. 2008). ...
The kea (Nestor notabilis) and other New Zealand forest birds are threatened by predation by introduced mammals. Mammal control for biodiversity conservation in New Zealand commonly involves the aerial application of cereal-pellet baits containing sodium fluoroacetate (‘Compound 1080’), but its effectiveness for kea conservation has not previously been assessed. This study examined the effects of aerial 1080 on the reproductive success of kea in a lowland rimu forest on the West Coast of New Zealand’s South Island. We measured three parameters which collectively describe annual reproductive success (nesting frequency, nest survival and final chick count), within a Before-After-Control-Impact experiment. The Impact site was a 30 000 ha area over which 1080 baits were aerially applied in the spring of a rimu (Dacrydium cupressinum) mast year (i.e. with heavy seedfall), with the After phase of the experiment lasting for two kea nesting seasons. The invasive mammals ship rat (Rattus rattus), brushtail possum (Trichosurus vulpecula) and stoat (Mustela erminea), which are potential predators of kea nests, were much less abundant in the Impact site after 1080 application, on the basis of standard indexing techniques. There was strong statistical support for an effect of aerial 1080 on kea nest survival. Aerial 1080 improved the odds of daily nest survival by a factor of 9.1 at the treatment site. Nest survival rates in the Control and Impact sites, before the application of 1080, were 21% and 46.4%, respectively. After the application of 1080 to the Impact site, nest survival increased to 84.8% in this site, whereas it declined to 12.2% in the untreated Control site. This substantial positive effect of aerial 1080 on kea nest survival is attributed to the effective control of mammalian nest predators, particularly the secondary poisoning of stoats.
... Predation, either by native or invasive predators, is often identified as a major determinant of post-release mortality, limiting the success of released individuals to form a viable population (Innes et al., 1999;Moseby et al., 2011;Seddon et al., 2007). High mortality due to predation after release has been associated mainly with the naivety of captive-bred individuals (Aaltonen et al., 2009;Biggins et al., 2011). ...
... After release the several possible hypothesis on interaction patterns generated by network models can be refined according to observation and the interaction networks can be constantly reevaluated. Depending on the observed changes, the need for interventions, such as resource provisioning or predator control (in the case of exotics) (e.g., Innes et al., 1999), may be anticipated. ...
Rewilding encompasses management actions such as reintroductions and translocations with the purpose of restoring ecological processes and ecosystem functions that were lost when species were locally extirpated. The success of a species introduction is conditioned by multiple factors, in particular, ecological interactions. To predict the fate of the introduced population and the community-level outcomes of the introduction, species interaction patterns need to be considered. Here I propose that ecological network models can help in rewilding projects in at least three ways. First, combining ecological information and probabilistic models it is possible to infer the most likely ways whereby the introduced species will integrate the community and which will be its role in the topology of the food web. Second, by determining the species more likely to interact directly or indirectly with the introduced species, it is possible to identify those species that may affect the success of the introduction and those that are more likely to be affected. Third, by constructing potential interaction networks representing the rewilding scenario, one can infer the possible ways by which the overall structure of the network will change and thus devise more efficient plans to monitor the community. Network models can be an important asset in rewilding, helping in feasibility and risk assessment as well as in monitoring the consequences after species release.
... The paradigm example is the eight-year experiment run by Innes et al. (1999). It listed the possible causes of the decline of the North Island kōkako and predicted the results from management actions targeted at each cause and no other. ...
... Per capita recruitment is assumed to be constant with prey density (i.e., the number of recruits is assumed to increase as the population increases) until resources become limiting and negative feedbacks reduce net recruitment as prey numbers approach carrying capacity (e.g., for song sparrows, Melospiza melodia, Arcese and Smith 1988). House mice (Mus musculus), for example, display various forms of spacing behavior that appear to regulate their populations through density-dependent F I G U R E 2 Examples of empirically derived predator density-impact functions for vulnerable secondary prey species, showing relationships between: percentage trap catch of brushtail possums (Trichosurus vulpecula) and percentage of pairs of North Island k okako (Callaeas cinerea) fledging young (a) (modified from Innes et al., 1999); mouse printing rates of tracking tunnels and numbers of southern grass skinks (Oligosoma polychroma) (b) and ground w et a (Hemiandrus spp.) (c) in pitfall traps (modified from Norbury et al., 2022); ship rat (Rattus rattus) tracking index and number of kerer u in 5 min bird counts (d) (reproduced from Carpenter et al., 2021); and residual ship rat tracking index (RTI) and predicted rat control effect size on recovery rates of deeply endemic New Zealand bird species for each endemicity level 7 years after the onset of control (e) (solid lines, predicted mean effect size; marker sizes depict relative weight each study contributed to overall effect size; shading, 95% confidence band; dotted lines, 95% prediction interval upper and lower bounds) (reproduced from Binny et al., 2020, with permission from Wiley). Approximate predator thresholds are apparent where prey recruitment or population size rapidly increase where predator density indices are less than about 10%. ...
Abstract Many of the world's native fauna suffer unsustainable losses from invasive mammalian predators. Conservation managers control predators on the premise that if large numbers are removed, prey will respond. This is sometimes true, but not always. Empirical relationships between predator densities and responses of vulnerable prey in Oceania often show little or no response across a broad range of predator reductions, with positive responses only at low threshold predator densities. Even then, some prey populations fail to respond. More research is required to identify predator thresholds across a range of prey taxa. This uncertainty of outcomes, coupled with the considerable cost of mammalian pest control, risks little or no return from limited conservation funds. A unifying theory is required to help understand why conservation outcomes from predator control are so variable despite the best efforts of conservation managers, and to expedite the right kind of management for a given prey species. We argue that a modern synthesis of numerical and functional response theory, in the form of total response models, provides such a theory. Stochastic consumer‐resource models are recommended for dynamic systems, but they are difficult to parameterize. Total response models, on the other hand, present a simple conceptual framework that managers can use as a heuristic to understand predator–prey systems, help explain some of the variability in predator control outcomes and stimulate thinking about other management options that can be integrated with predator control to improve conservation outcomes. Five rules of thumb are suggested to assist conservation managers.
... Importantly, a reduction in trapping efforts could allow stoat populations to return to pre-control densities, with few founders, within only 2 -3 years (Anderson et al. 2016). Thus, maintaining stoat populations at effectivelyzero levels, or at least levels low enough to benefit native populations (Innes et al. 1999, Hooson and Jamieson 2003, Prada et al. 2014, requires continual, active trapping ). This requirement is true for any location with a high probability of incursion, whether a mainland or near-shore island site. ...
... In a study in natural areas in Hawaii, Nelson et al. (2002) determined that black rats rapidly reinvaded depopulated areas after removal efforts were completed. Similar results have been noted elsewhere (Innes et al. 1999;King et al. 2011). Although we assessed black rat activity immediately following the completion of removal efforts, it is possible that rats moved into our monitoring plots from adjacent areas, subsequently biasing our results. ...
... This change comes about because possums prefer to eat fruit, flowers, and leaf buds, disrupting the formation of seedlings and the succession of Aotearoa-New Zealand's forests. They also compete with many native fauna for food and habitat, destroying the nests of birds such as kererū (Hemiphaga novaeseelandiae) (Powlesland, Dilks, Flux, Grant, & Tisdall, 1997) and kōkako (Callaeas wilsoni) (Innes et al., 1999). Possums have been recorded killing and eating tītī (Ardenna grisea), pīwakawaka (Rhipidura fuliginosa), and tāiko (Pterodroma magenta), both the adult birds and chicks (Sadlier, 2000). ...
Throughout the world, Aotearoa-New Zealand is recognised for its extraordinary biodiversity. However, many species that make up this distinctive biodiversity are under threat of extinction due to human impacts, such as the ill-considered introduction of particular animals. Many New Zealanders participate in the protection and restoration of their environment, which involves the lethal control of these introduced animals. Primary school children (5–13 years old) engage in conservation education as part of their learning, which aims to develop their abilities to take informed action to protect and restore our environment, sometimes including lethal control of introduced animals. Recently, concerns have been raised that children learning about the lethal control of introduced animals does not align with the values that should be explored and encouraged according to Aotearoa-New Zealand’s national curriculum. We argue that conservation education, including learning about the lethal control of introduced animals, encourages children to explore and encourage these values, namely valuing the diversity in their heritages, ecological sustainability, participation for the common good, equity, innovation, and respect for others.
... Chew cards are an increasingly widely used monitoring device for mammals in New Zealand, as they are cheap, easy to use and highly sensitive to possums and rodents (Forsyth et al., 2018;Sweetapple & Nugent, 2011). Chew card indices are correlated with other indices of possum and rodent abundance, which have been shown to relate to nesting success for several native bird species (Armstrong et al., 2006;Forsyth et al., 2018;Innes et al., 1999;Innes et al., 2004;Ruffell et al., 2015;Sweetapple & Nugent, 2011). ...
Urbanization, and the drastic loss of habitat it entails, poses a major threat to global avian biodiversity. Ecological restoration of urban forests is therefore increasingly vital for native bird conservation, but control of invasive predators may also be needed to sustain native bird populations in cities where species invasions have been particularly severe.
We evaluated restoration success by investigating changes in native bird communities along a restoration chronosequence of 25 restored urban forests representing 72 years of forest development, which we compared to two target reference systems and a control system. We hypothesized that total species richness and relative abundance of native forest birds would increase with the age of restoration planting. We further hypothesized that relative abundance of rats, possums and cats would negatively impact native birds, while amount of native forest in the surrounding landscape would have a positive effect.
We used structural equation modelling (SEM) to investigate the relative influence of forest structure (complexity index, tree height, canopy openness, basal area, species richness and density), landscape attributes (patch area, perimeter length, landscape composition within three buffer zones, distance to the nearest road and water source) and invasive mammalian predator indices of relative abundance on total species richness and relative abundance of native forest birds.
Species richness increased with age of restoration planting, with community composition progressing towards that found in target reference systems. SEM revealed that years restored was a direct driver of bird species richness but an indirect driver of abundance, which was directly driven by canopy openness. Contrary to our predictions, invasive mammals had no significant effect on native bird species richness or abundance.
Our results demonstrate that provision and improvement of habitat quantity and quality through restoration is the vital first step to re‐establishing native forest bird communities in cities.
... Despite its theoretical appeal, examples of the implementation of formal AM are relatively scarce (Westgate et al., 2013). Examples include its application to the management of native species, e.g., wolf Canis lupus in North America (Varley and Boyce, 2006) or Sika deer Cervus nippon in Japan (Kaji et al., 2010), and invasive species, e.g., brushtail possum Trichosurus vulpecula and ship rat Rattus rattus in New Zealand (Innes et al., 1999), and feral pigs Sus scrofa in Australia (Cowled et al., 2008;Nugent et al., 2018). A notable highly successful implementation of AM in Europe is the transnational shooting quota setting plan for a migratory waterbird population (Madsen et al., 2017) and the control of invasive American mink Neovison vison in Scotland (Bryce et al., 2011). ...
Invasive non-native species eradication attempts are typically large and expensive projects that benefit from the support of quantitative tools, such as population models, to be completed within the scheduled and funded time. Managed ecosystems are constantly changing due to population and ecosystem dynamics. Accordingly, any model predictions need to be updated, using different sources of data, to inform the project about the progress toward eradication. The stoat Mustela erminea was introduced to the hitherto predatory land mammal free Orkney archipelago around 2010. In 2016, a project aiming to eradicate stoats to preserve ecologically and economically important native wildlife was designed and implemented. It entailed a "knockdown" phase followed by a "mopping-up" phase to remove stoats that escaped capture. We used data from this project to iteratively predict the progress toward eradication. We applied spatially explicit individual-based models to estimate the proportion of stoats being exposed to capture, and then compared these simulation-based predictions with removal data, allowing us to estimate changes in the population size through time. We also used sighting data from members of the public to refine eradication probability. We were also able to demonstrate how the initially wide uncertainty gradually diminished as more evidence accumulated. The information derived from different types of data and quantitative models allowed us to track the effectiveness of current trapping approaches and to help to inform project managers about when the project achieved the knockdown phase milestone. Our analyses confirmed that the expected magnitude of the initial knockdown phase has been achieved in some areas, but also revealed spatial and temporal heterogeneity in the distribution of captures, most likely caused by the sequential trapping and stoat movement and trap shy stoats exposed to capture but not caught. This heterogeneity calls for additional data sources (e.g., from camera traps or detection dogs) to estimate the proportion of trap-shy individuals and the size of the untrapped population, and ultimately the feasibility of eradication.
... One explanation may be that numbers of ship rats in northern New Zealand forests, especially where there are no bellbirds, are higher than in habitats further south where bellbirds persist (see Brockie 1992). Although the relative densities of ship rats throughout the country have not been compared simultaneously they are known to be relatively higher in northern New Zealand (Craig 1983;Dowding & Murphy 1994;Clout et al. 1995;Lee 1999;Innes et al. 1999). In contrast, in the lower North Island and in the South Island, ship rats are generally recorded in lower numbers (Brockie 1992). ...
New Zealand bellbirds (Anthornis melanura) disappeared suddenly from the northern New Zealand mainland and several large northern islands in the late 19 th century. During the past 75 years, several unsuccessful attempts were made to reintroduce them. Between 1988 and 1991, four translocations (111 birds) were made to Waiheke Island near Auckland, sourced from Kaingaroa (21 birds) and Cuvier Island (90 birds). The birds were conspicuous immediately after release but became progressively less visible within six months and the translocations failed. While the cause(s) of failure are unknown, predation by mammalian predators, especially ship rats (Rattus rattus) is likely to have been a critical factor. Other possible reasons for failure of bellbird translocations are discussed, along with the reasons why original bellbird populations disappeared from northern New Zealand and subsequently failed to re-establish. Lee, M. 2005. Failed attempts to reintroduce bellbirds (Anthornis melanura) to Waiheke Island, Hauraki Gulf, 1988-91. Notornis 52(3): 150-157.
... During this study, swiftlets nested in new areas at Mahlac Cave after the initial suppression of BTS, which suggests BTS may have been limiting nesting habitat through either consumptive and non-consumptive effects (e.g., Breviglieri and Romero 2016). By concurrently studying BTS and swiftlets in an adaptive management framework, we could understand how the management of BTS impacts the recovery of swiftlets beyond number of BTS removed (e.g., Innes et al. 1999;Buxton et al. 2014). Studies focused on population estimation, reproductive success, or survival of swiftlets while concurrently following BTS (i.e., visual searches, radio-tracking, or video) would highlight vulnerable life stages and inform how predation, nest site constraints, and perceived risk impact Mariana swiftlets (e.g., Kokko et al. 2004). ...
Invasive predators are known to have negative consumptive and non-consumptive effects on native species, but few examples show how the abundance of native prey may influence an established invasive predator. We compared invasive brown treesnakes (Boiga irregularis; BTS) found in caves occupied by endangered Mariana swiftlets (Aerodramus bartschi) to snakes found in nearby forests and caves without birds to quantify how the abundance of native avian prey impacts BTS abundance and behavior on Guam. From 2011 to 2017 we removed 151 BTS in caves occupied by swiftlets and never observed BTS in caves without birds. Notable locations included snakes foraging near swiftlets and in holes that allowed cave access and escape from capture. Of 43 BTS with gut contents, 27 (63%) contained swiftlets. BTS in swiftlet-occupied caves had greater fat mass compared to forests, indicating access to swiftlets may increase body condition and promote reproduction. Number of ovarian follicles was significantly greater in female snakes from swiftlet-occupied caves compared to those from ravine, but not limestone forests; evidence of male BTS being more capable of reproduction was limited (i.e., fewer non-discernible but not significantly larger testes in snakes from caves). Assuming other limiting factors are considered, altering the functional response of predators through the modification of caves or interdiction lures to exclude or hinder the largest BTS could bolster swiftlet populations by increasing nesting refugia in currently-occupied caves and facilitate recolonization of historical caves.
... Thus, management to create habitat and improve habitat quality is often a primary focus of conservation efforts. These efforts have had notable success in recovering declining wildlife populations by improving survival and reproductive rates and increasing population size (Catlin et al., 2011;Innes et al., 1999;Warren, 1991;Whitehead et al., 2008). However, there are also many instances wherein management efforts were ineffective or even detrimental to target species, so much so that ecological restoration is considered among the top three anthropogenic causes of ecological traps (Armstrong et al., 2007;Ausden et al., 2001;Robertson et al., 2013). ...
Habitat quality regulates fitness and population density, making it a key driver of population size. Hence, increasing habitat quality is often a primary goal of species conservation. Yet, assessments of fitness and density are difficult and costly to obtain. Therefore, species conservation often uses “best available science,” extending inferences across taxa, space, or time, and inferring habitat quality from studies of habitat selection. However, there are scenarios where habitat selection is not reflective of habitat quality, and this can lead to maladaptive management strategies. The New England cottontail (Sylvilagus transitionalis) is an imperiled shrubland obligate lagomorph whose successful recovery hinges on creation of suitable habitat. Recovery of this species is also negatively impacted by the non‐native eastern cottontail (Sylvilagus floridanus), which can competitively exclude New England cottontails from preferred habitat. Herein, we evaluate habitat quality for adult and juvenile New England and eastern cottontails using survival and density as indicators. Our findings did not support selection following an ideal free distribution by New England cottontails. Instead, selected resources, which are a target of habitat management, were associated with low survival and density and pointed to a complex trade‐off between density, survival, habitat, and the presence of eastern cottontails. Further, movement distance was inversely correlated with survival in both species, suggesting that habitat fragmentation limits the ability of cottontails to freely distribute based on habitat quality. While habitat did not directly regulate survival of juvenile cottontails, tick burden had a strong negative impact on juvenile cottontails in poor body condition. Given the complex interactions among New England cottontails, eastern cottontails, and habitat, directly assessing and accounting for factors that limit New England cottontail habitat quality in management plans is vital to their recovery. Our study demonstrates an example of management for possible ecological trap conditions via the application of incomplete knowledge.
... Ikeda [41] and the Ministry of the Environment [42] have pointed out the necessity of sharing information for successful racoon management. Accumulating cases of management failures, in terms of invasive nonnative species management, and analyzing such problems, is indispensable for implementing future management programs more effectively [57,58]. It is important to share lessons about failed programs and efforts. ...
Background
The raccoon (Procyon lotor) is an invasive, non-native species in Japan. Throughout the country, it causes significant agricultural damage and negatively affects native biodiversity. Most of the responsibility for raccoon management lies with local government, and there are still many challenges to be overcome. Although raccoon populations have not been eradicated, intensive control campaigns such as focus on the early stages of invasion have controlled raccoons in some regions. To improve the national management of raccoons, we conducted a survey on raccoon management systems in local government departments considered to solve the challenges recognized in many areas. During 2014 and 2015, we surveyed three different municipal departments about raccoon management measures. The semi-structured interview survey covered two topics: (1) the situation leading up to the current management system; (2) the current management system.
Results
Our results describe the scope and methods used in raccoon management. The government staff managed raccoons using monitoring, employing a variety of methods, a range of budgets, and various role divisions. The management practices are similar in that they share a sense of taking precautions, collaborating with stakeholders, understanding that adequate methods must be used, and obtaining support from experts.
Conclusions
Our case studies reveal the challenges in raccoon management faced by local government officers in regions with active control. The management systems and methods that we surveyed seemed to be effective in solving problems in both developed and undeveloped areas.
... Particularly endemic bird species have benefitted from high intensity of mammal control in New Zealand (Fea et al. 2020). The reduction of population densities of ship rats and brushtail possum to very low levels has resulted in an increased breeding success in the endangered North Island kokako (Callaeas cinerea wilsoni) (Innes et al. 1999). Starling-Windhof et al. (2011) have shown that predator control increased nesting success for New Zealand fantail (Rhipidura fuliginosa), grey warbler (Gerygone igata), bellbird (Anthornis melanura) and South Island robin (Petroica australis). ...
On Aotea/Great Barrier Island, New Zealand, two invasive rat species (Pacific rats and ship rats) pose risks to the ecosystems and challenge the management in two sanctuaries. At Glenfern Sanctuary (83 ha) an eradication has successfully removed ship rats and a predator-proof fence prevents reinvasion. However, Pacific rats persist in low abundance. At Windy Hill Sanctuary (770 ha) intensive rodent control maintains both species at low abundance despite ongoing reinvasion. A capture-mark-recapture study was conducted between February and April in 2016 and repeated between July and September 2017 to determine population densities, confirm species composition, and analyse the effects of time, population density, and interspecific competition on rat behaviour. Live traps were monitored with camera traps to analyse behaviour of rats around traps. Population density and detection probability of Pacific rats varied between times reflecting seasonality in food abundance and rat reproduction. The detection probability of Pacific rats also differed between sites, being higher at Glenfern Sanctuary than at Windy Hill Sanctuary, presumably due to interspecific competition with ship rats. Where Pacific rats were the sole species they were captured in traps in the first night. However, in coexistence with ship rats, Pacific rat detection was delayed by at least ten days. Population density influenced the number of trap encounters and interactions but did not significantly influence the capture rate. Interspecific competition was identified as problematic for monitoring, controlling, and eradicating Pacific rats.
... Possum browsing on preferred palatable species significantly influences forest composition through impeding the regeneration capacity of trees and ecological succession (Windley and Foley 2015, Holland et al. 2017, Department of Conservation 2018 (Cochrane et al. 2003). Additionally, many plants that are vulnerable to possum browsing (such as mistletoes) are now listed as rare due to habitat loss and an insufficient number of specialized pollinators-particularly birds Kelly 2001, Sweetapple 2008 (Innes et al. 1999, Innes et al. 2004, Elliott et al. 2010, Innes et al. 2010, Trewick and Olley 2016. ...
Worldwide, introduced pest species create significant challenges to native biodiversity and individual health. New Zealand has an extensive history of attempting to protect biodiversity from introduced pests such as the Brushtail possum (Trichosurus vulpecula [Diprotodontia: Phalangeridae]). Success has been achieved on a small scale, but the transition to the whole country management poses new issues. Therefore, this review uses the framework of 'Predator Free 2050' to summarize current practices and scrutinize new technologies. Importantly, we include a toxicology focus to the discussion, providing detail on the mechanism(s) of action that inform decisions regarding the pros and cons for the use of various chemical agents. Currently, the New Zealand government supports the use of sodium fluoroacetate (1080) for predator control on a mass scale, but this comes with a social opposition that is not always reflective of the underlying science. Understanding this controversy is vital if new strategies are to be deployed to achieve large-scale pest management. We use New Zealand as a case study in this area because its unique and isolated ecosystem provides a global opportunity for understanding new technologies and best practice.
... Rats are a frequent cause of predation on eggs, chicks and sitting adult birds. They also eat native invertebrates (Innes et al. 1999;Innes 2005). Stoats were introduced to New Zealand in the 1880s to control rabbits. ...
... Rats are a frequent cause of predation on eggs, chicks and sitting adult birds. They also eat native invertebrates (Innes et al. 1999;Innes 2005). Stoats were introduced to New Zealand in the 1880s to control rabbits. ...
Conservation policy in New Zealand is centred around an objective to totally eradicate three invasive species; the ship rat (Rattus rattus), the brushtail possum (Trichosurus vulpecula) and the stoat (Mustela erminea), by 2050. The preferred control method to achieve this is large scale poisoning operations with 1080 and similar toxins. This project is backed up by governmental and non-governmental agencies and surrounded with discourse of ‘war’ and ‘invasion’. The ‘Big Three’ predators are endowed with sinister motives as a means of mobilising support. This self-described ‘war’ is evaluated in terms of ‘just war’ theory and found wanting. In particular there are issues with the recruitment of children for killing, humiliation of combatants, questionable economic motives for the ‘war’, deception by government agencies, lack of consultation, a lack of consideration of alternatives, the use of excessive suffering, and unrealistic expectations. An alternative paradigm of ‘compassionate conservation’ is proposed for New Zealand. Instead of trying to get back to a stable pre-colonial state of nature, I propose a holistic approach that respects both ecosystems and their members and takes into account new understandings of ecosystems as dynamic processes.
... This is particularly true in New Zealand, where introduced mammalian predators are the primary factor limiting endemic forest bird abundance in large forest tracts by predation of eggs, chicks, and incubating adults. Therefore, bird populations frequently recover after pest predator control (Innes et al. 1999;Moorhouse et al. 2003;Smith & Westbrooke 2004;Armstrong et al. 2006;Innes et al. 2010). In the absence of effective ship rat (Rattus rattus) and brushtail possum (Trichosurus vulpecula) management, tūī nesting success in the Waikato is poor (Innes et al. 2005;Innes et al. 2015). ...
Maungatautari is a 3,240 ha pest-fenced ecosanctuary free of virtually all mammalian predators in Waikato,
New Zealand. We used triennial 5-minute counts within the ecosanctuary and biennial surveys of residents up to 20 km
from the perimeter pest fence to measure spillover of tūī from Maungatautari into the surrounding area over a 9-year
period (2006–2014) following pest eradication. Following pest eradication in the ecosanctuary, tūī relative abundance
increased there and in the surrounding largely unmanaged area. The mean number of tūī per 5-minute count within
the ecosanctuary was 2.23 (se = 0.163) in 2005 and increased following predator eradication in 2006 to 3.33 (se = 0.206)
in 2008, 3.76 (se = 0.193) in 2011, and 2.68 (se = 0.279) in 2014. The mean maximum number of tūī at one time observed
by residents in the largely unmanaged area increased from 4.4 (max = 47, n = 320) in 2006 to 15.6 (max = 300, n = 138)
in 2014. Tūī numbers in both the ecosanctuary and the surrounding area were positively correlated with time since pest
eradication. In the largely unmanaged area surrounding Maungatautari, tūī numbers were also positively correlated
with provision of artificial food, and negatively correlated with distance from the ecosanctuary. Wind was negatively
correlated with the number of tūī recorded in 5-minute counts at Maungatautari. Our findings show that pest-free
ecosanctuaries can facilitate increased abundance of volant birds in surrounding landscapes if habitat is available.
... Small mammals, mesocarnivores, and avian predators have been successfully targeted in other predator control efforts (Innes et al. 1999, Powlesland et al. 1999, Moorhouse et al. 2003, Smith et al. 2010, 2011, suggesting that traditional predator control methods have the potential for success in salt marshes. The potential mammalian predators at Forsythe NWR include raccoons (Procyon lotor), river otter (Lontra canadensis), red fox (Vulpes vulpes), American mink (Neovison vison), and meadow vole (Microtus pennsylvanicus). ...
Globally limited to 45,000 km2, salt marshes and their endemic species are threatened by numerous anthropogenic influences, including sea-level rise and predator pressure on survival and nesting success. Along the Atlantic coast of North America, Seaside (Ammospiza maritima) and Saltmarsh (A. caudacuta) sparrows are endemic to salt marshes, with Saltmarsh Sparrows declining by 9% annually. Because vital rates and factors affecting population persistence vary for both species, local estimates are necessary to best predict population persistence in response to management actions. We used a metapopulation model to estimate the population viability of the breeding Seaside and Saltmarsh sparrow populations in coastal New Jersey over a 42-yr period. We incorporated empirical data on the vital rates and abundances of these populations and simulated the effect of low (0.35 m) and high (0.75 m) levels of sea-level rise. We found that the Seaside Sparrow population persisted under both sea-level rise scenarios; however, the Saltmarsh Sparrow population reached a quasi-extinction threshold within 20 yr. Using the same framework, we modeled potential management scenarios that could increase the persistence probability of Saltmarsh Sparrows and found that fecundity and juvenile survival rates will require at least a 15% concurrent increase for the local population to persist beyond 2050. Future field research should evaluate the feasibility and effectiveness of management actions, such as predator control, for increasing Saltmarsh Sparrow vital rates in order to maintain the species in coastal New Jersey.
... As well as consuming vegetative parts of mature plants, its consumption of fruits, seeds and seedlings can reduce seedling establishment (Wilson et al. 2003;Grant-Hoffman & Barboza 2010). Predation by R. rattus also has the potential to reduce populations of large invertebrate species, reptiles, amphibians, forest birds and seabirds (Towns & Daugherty 1994;Innes et al. 1999Innes et al. , 2010St Clair 2010;Ruscoe et al. 2013;). While lizards have been confirmed as prey items of R. rattus elsewhere (Clark 1981;Caut et al. 2008), they have not been reported in the stomach contents of this species in New Zealand. ...
... Applications of adaptive management to conservation have taken longer to develop (Runge, 2011). These have included predator control (Innes et al., 1999;Parkes et al., 2006;Whitehead et al., 2008), weed suppression (Gannon et al., 2013), habitat management (Aldridge et al., 2004;Nicol et al., 2015), fire management (Moore et al., 2011), and reintroductions (Armstrong et al., 2007). ...
Monitoring is an essential component of adaptive management, and a carefully designed program is needed to ensure high-quality data and inferences over realistic time scales. Co-operation among agencies and incorporating citizen science may help enhance learning while reducing the financial costs of monitoring. We seek to realise this potential while conserving the Australian malleefowl (Leipoa ocellata). An established network of citizen scientists provide low-cost, sustainable annual monitoring data, yet the most effective actions for conserving malleefowl remain highly uncertain. The continent-wide species' distribution presents significant challenges, including multiple environmental strata to sample and numerous management jurisdictions. We outline an adaptive management framework that aims to unify malleefowl conservation priorities nationally, and target monitoring efforts. We elicited a model structure for the drivers of, and threats to, malleefowl persistence in a workshop with land managers and advocates. We parameterised 80 uncertain interactions within this structure using novel ensemble modelling techniques and identified the effectiveness of predator control as a critical uncertainty affecting malleefowl persistence. We developed a classical, spatially replicated experimental design to test whether malleefowl breed more frequently where predators are suppressed. The proposed monitoring design will rely on the contributions of several dozen land managers and 200–300 citizen scientists annually. We have developed a broad stakeholder base, a proactive communication strategy, and an agile approach to accessing resources to foster resilience and longevity in the monitoring program. If malleefowl conservation successfully adapts in response to monitoring outcomes, it will become one of the largest adaptive management programs on the planet.
... A12 traps would offer an additional control tool that had significant advantages over existing methods. ETET also wish to reintroduce the North Island kokako (Callaeas cinereus), a bird species whose threat status is "Nationally Vulnerable," to this site, which would require maintaining an RTCI for possums of less than 5% (Innes et al. 1999). ...
... Species such as stoats (Mustela erminea), weasels (Mustela nivalis) and brushtail possums (Trichosurus vulpecula) continue to inflict major ecological harm to native biota (McLennan et al. 1996, Clout 2006. To ensure the survival of many native species on the mainland, continued predator control is vital (Innes et al. 1999, Whitehead et al. 2008). ...
... However, breeding biology can be time consuming and expensive to study, particularly in isolated areas such as the subantarctic, and for cryptic species (Innes et al. 1999). Often this results in a bias towards populations that are easy to access or study, and uninformed management decisions for understudied populations (Trathan et al. 2015). ...
Eco-tourism is increasing in popularity worldwide, particularly in previously isolated areas such as Antarctica and the subantarctic. This may be increasing the levels of human disturbance stimuli (human-related presence, objects or sounds), which can have impacts on wildlife at an individual level (behaviourally and physiologically) and at a population level. Human disturbance (the response of an animal to a disturbance stimulus) has been studied in most penguin species, showing both inter- and intra-specific differences in responses to disturbance stimuli at similar distances. The Yellow-eyed Penguin (Megadyptes antipodes) is negatively impacted by human disturbance stimuli, but very little research of any kind has been conducted on the subantarctic population. This is despite some areas within the subantarctic being regularly exposed to tourism, and the subantarctic population making up an estimated 60% of the entire species. I used an experimental approach to investigate the behavioural impacts of human disturbance stimuli on subantarctic Yellow-eyed Penguins, on Enderby Island. Human presence significantly changed their behaviour, resulting in an increased time spent vigilant and a decrease in the frequency of maintenance behaviours. By modelling the probability of disturbance at varying distances from the penguin to the human, I showed the current minimum approach distance of 5 m (with a 99% chance of disturbance) was not effective. I also quantified the breeding biology of subantarctic Yellow-eyed Penguins, and investigated the impact of human disturbance stimuli on their breeding success. There was no difference in nesting success (expressed as number of eggs, chicks and fledglings surviving per pair) between the disturbed and undisturbed site and no significant difference in the average weight and body size of fledglings at the disturbed site compared to fledglings at the undisturbed site. My results indicate that at current levels human disturbance stimuli has a behavioural impact on subantarctic Yellow-eyed Penguins, but a population-level impact was not detectable. This may be due to the low level of tourism and high degree of tourism management in the New Zealand subantarctic, and the resulting low number of interactions between penguins and humans. Enderby Island tourism may therefore be an example of sustainable eco-tourism and successful management, although more research including multi-year studies would be needed to confirm this.
... The first of these were Mainland Islands established in 1995-96 by DOC (Saunders and Norton 2001). Such unfenced sites yield conservation gains (Innes et al. 1999;Gillies et al. 2003;Armstrong et al. 2006), but success is hampered by constant reinvasion, concern about sustained toxin use, and unhelpful increases of remaining pests after removal of others. For example, there were increases in rabbits (Oryctolagus cuniculus) and house mice at Trounson Mainland Island following control of stoats, ship rats, and feral cats (Gillies et al. 2003). ...
... However, in 'season 2' the A24s were able to reduce rats to non-detectable levels at both sites during the trial period. One night tracking tunnel indices are a coarse measure of rodent populations, but we consider them to be reliable for assessing rat relative-abundances (Brown et al. 1996;Johnston 2003) and the index can be related to some conservation outcomes (Innes et al. 1999;Armstrong et al. 2006). It is possible that the effects of nearby rat control operations in Boundary Stream could have influenced the 'season 2' result there. ...
On 18 October 2010 the Minister of Conservation announced that the Government would be spending $4 million to trial self-resetting traps through a rigorous testing programme. The purpose of the project was to assess the feasibility and efficacy of using self-resetting traps for ground based pest control for conservation. As a result of this initiative, the traps selected for testing were the Goodnature Ltd. A12 automatic humane trap for possums and the Goodnature Ltd. A24 automatic trap for rats and stoats.
Operational scale trials of the A12 possum traps were conducted between November 2011 and June 2013 at Trounson Kauri Park in Northland and in the Casino Block in Northern Te Urewera. WaxTag® and leg-hold trap indices of possum abundances indicated that populations of this pest were reduced to low levels in Trounson Kauri Park but not in the Casino Block, even though many possums were killed there.
Operational scale trials of the A24 traps to target stoats were conducted between September 2012 and May 2014 in the Otamatuna and Mangaone blocks in Northern Te Urewera and at the Rotoiti Nature Recovery Project at Nelson lakes. Tracking tunnel indices of stoat abundances at each site, plus kiwi chick monitoring in Northern Te Urewera, indicated that populations of this pest were suppressed in both areas during the 2012/13 season but not during the 2013/14 season. We suspect this was mostly due to progressive mechanical failures of early and mid-trial versions of the devices.
The rat control component of the A24 trials was done in the Onepu block in Northern Te Urewera and at Boundary Stream in the Hawkes Bay. Tracking tunnel indices of rat abundances indicated that populations of this pest were not suppressed to acceptable levels at either site during the 2012/13 season, however, they were suppressed to non-detectable levels at both sites during the 2013/14 season. We believe the 2013/14 season result was because an improved auto-lure was used and approximately 60% of the traps deployed at these sites were the later, more mechanically reliable versions of the A24.
In 2014 and 2015 we will be working with Goodnature Ltd. to field test the medium to long-term mechanical reliability of the devices plus the latest versions of their auto-lures for stoats and possums.
... The risk-averse approach in pest control ''overharvests'' the pest to minimize any possible impacts. Such an approach might be desirable in cases of high uncertainty (e.g., where the critical pest species or threat is unclear and all candidate threats are, therefore, managed) and high risk (e.g., as with the protection of some endangered species), (Innes et al. 1999), but has opportunity costs when budgets are limited (Choquenot and Parkes 2001). The dogmatic approach deliberately avoids any analysis of uncertainty or risk in case fixed policy positions are disturbed. ...
Government conservation agencies in New Zealand and the Australian state of Victoria spend 20% and 4%, respectively, of their annual budgets to manage a small part of the problem caused by introduced mammals. Managers' uncertainty about the optimal strategies for applying pest control has led to major differences in management practices within the single pest control programs in both countries. Monitoring under a trial-and-error approach has not removed uncertainty but has led managers to support the application of adaptive management for their pest control. Control of brushtail possums (Trichosurus vulpecula) in New Zealand and red foxes (Vulpes vulpes) in Victoria, Australia, is conducted over large areas in many operations, but individual managers apply different control regimes based on the perceived benefits and opportunity costs. We report on the processes used to set up the first adaptive management experiments in pest control in New Zealand or Australia that combine the competing models approach (used when only a single management regime can be applied at one time) with an experimental approach (made possible when different management regimes are applied simultaneously in different places) with the aim of elucidating benefits and costs of the different strategies used to control the 2 pests. (WILDLIFE SOCIETY BULLETIN 34(1):229–236; 2006)
... Auckland tree wētā are classed as highly vulnerable by Norbury et al. (2015) because they appear most likely to respond with an exponential reduction in numbers as predator numbers increase (Ruscoe et al. 2013). As such, they are likely to be good indicators for kōkako and ground wētā, which are also highly vulnerable to rat and hedgehog predation, respectively (Innes et al. 1999;Jones et al. 2013;Norbury et al. 2015). Arboreal tree wētā are likely to act less well as an indicator for female North Island robins (Petroica longipes; Aves: Petroicidae), which show a proportionate response to increasing rat abundance (Armstrong et al. 2006;Norbury et al. 2015). ...
Indicator taxa are increasingly being used to evaluate the natural environment because they provide both quantified and simplified information about complex phenomena and because they result in huge cost savings compared with monitoring entire biotas. In this paper, we examine the suitability of an iconic New Zealand invertebrate, the tree wētā (Orthoptera: Anostostomatidae: Hemideina species), as a bioindicator for invertebrates under a national biodiversity monitoring scheme in New Zealand. Tree wētā are common and widespread in New Zealand, comprising a distinctive component of the native invertebrate fauna, being large-bodied (up to 40 mm in length), relatively long-lived, flightless, and nocturnal. Arboreal tree wētā species are commonly monitored in conservation areas containing scrub or forest, particularly after mammal control, because they can be easily monitored using artificial roosts without harming them and they are readily identified by field workers. We evaluated whether data supported the use of tree wētā as a range of bioindicators for such monitoring and conclude that the arboreal species are good indicators for monitoring the effects of controlling the abundance of insectivorous mammals and that they are likely to be reliable population indicators of taxa sensitive to mammalian predation pressure, especially by rodents. However, it is unlikely that arboreal tree wētā are useful population indicators of habitat change (e.g. degradation and fragmentation) as they commonly survive in exotic vegetation and urban gardens throughout New Zealand. Although poorly studied for indicator value, tree wētā may not be good biodiversity indicators although there are insufficient data to establish this. We recommend further research be undertaken to develop standardised methods for monitoring so that conservation managers and researchers produce results that are consistent and comparable across different locations.
Wildlife management aims to halt and then reverse the decline of threatened species, to sustainably harvest populations, and to control undesirable impacts of some species. We describe a unifying framework of three feasible options for evaluation of wildlife management, including conservation, and discuss their relative strengths of statistical and causal inference. The first option is trends in abundance, which can provide strong evidence a change has occurred (statistical inference) but does not identify the causes. The second option assesses population outcomes relative to management efforts, which provides strong evidence of cause and effect (causal inference) but not the trend. The third option combines the first and second options and therefore provides both statistical and causal inferences in an adaptive framework. We propose that wildlife management needs to explicitly use causal criteria and inference to complement adaptive management. We recommend incorporating these options into management plans.
Pureora Forest Park is one of the largest remaining and most ecologically and culturally significant areas of the native forest that once clothed almost all the North Island of New Zealand. Systematic logging and the establishment of sawmilling villages began in the Pureora area in the late 1940s. Concern about the effects of logging of virgin forest on native fauna accelerated until 1978, when a widely publicised tree-sitting protest led to a forced moratorium. The settlement that followed stopped the logging, closed the sawmills, and caused mass local unemployment and social conflict. The long-term solution required an integrated approach, reconciling the needs of economic resource utilisation with those of social welfare and biodiversity conservation. This paper describes the processes leading up to the unprecedented financial settlement that saved the forest, plus the details of the compensation package paid to timber companies for broken contracts, and the consequent benefits for conservation and tourism.
House mice are among the most widely distributed mammals in the world, and adversely affect a wide range of indigenous biota. Suppressing mouse populations, however, is difficult and expensive. Cost-effective suppression requires knowing how low to reduce mouse numbers to achieve biodiversity outcomes, but these targets are usually unknown or not based on evidence. We derived density-impact functions (DIFs) for mice and small indigenous fauna in a tussock grass/shrubland ecosystem. We related two indices of mouse abundance to five indices of indigenous lizard and invertebrate abundance measured inside and outside mammal-resistant fences. Eight of 22 DIFs were significantly non-linear, with positive responses of skinks (Oligosoma maccanni, O. polychroma) and ground wētā (Hemiandrus spp.) only where mice were not detected or scarce (< 5% footprint tunnel tracking rate or printing rate based on footprint density). Kōrero geckos (Woodworthia spp.) were rarely detected where mice were present. A further 9 DIFs were not differentiated from null models, but patterns were consistent with impacts at 5% mouse abundance. This study suggests that unless mouse control programmes commit to very low abundances, they risk little return for effort. Impact studies of invasive house mice are largely restricted to island ecosystems. Studies need to be extended to other ecosystems and species to confirm the universality or otherwise of these highly non-linear DIFs.
Les rats introduits (Rattus spp.) sont des espèces invasives majeures menaçant la biodiversité sur la plupart des îles de la Planète. Deux espèces, le rat noir (R. rattus) et le rat du Pacifique (R. exulans) vivent en sympatrie au sein des forêts de Nouvelle-Calédonie, où la question de la faisabilité et de l' intérêt de leur contrôle (i.e. limitation locale de leur 'abondance)pour la conservation de la biodiversité native est posée. En raison d'un manque de cadre conceptuel des projets de contrôle,nous avons d'abord réalisé une synthèse et une analyse des opérations de contrôle de rats invasifs dans les milieux naturels des îles du monde. Puis, nous avons cherché à caractériser et à comprendre la dynamique des populations de ces deux espèces de rats sympatriques ainsi que leurs interactions avec la biodiversité native en forêt dense humide du massif du Mont Panié.Des opérations de piégeage létal et de capture-marquage-recapture ont montré que les rats noirs étaient plus abondants que les rats du Pacifique. Les analyses de leur régime alimentaire ont révélé que les deux espèces ont à la fois des proies communes et des proies qui leur sont propres impliquant un renforcement ainsi qu'un élargissement de leurs impacts sur la biodiversité native. Les rats consomment une grande majorité de fruits et de graines, d'invertébrés et de Squamates mais les oiseaux, qui justifient souvent la mise en place de projets de gestion de rats, ne semblent pas ici être une de leur proie préférentielle. De potentiels effets positifs des rats sur la dispersion des graines ont également été mis en évidence au travers d'une comparaison du potentiel germinatif de graines après passage par leur tractus digestif et celui de frugivores natifs. Enfin, nous avons proposer des stratégies de piégeage létal afin de contrôler efficacement les populations de rats invasifs. Une meilleure compréhension des impacts des rats en situation de sympatrie ainsi qu' une meilleure connaissance du lien entre densité de rats et intensité des effets sur la biodiversité permettraient d'optimiser les stratégies de contrôle de rats invasifs lorsque l'éradication n'est pas envisageable.
Fenced ecosanctuaries may reduce predator presence at reserves by incorporating deterrents into pest management programmes. We quantified rodent visits to the steel hood of ecosanctuary fencing and illuminated our experimental sites to assess whether light could deter ship rats (Rattus rattus) and house mice (Mus musculus). Additionally, we assessed how mice used fencing in the presence and absence of ship rats by utilising two types of fence sections: one accessible to mice alone (along fencing within an ecosanctuary) and one accessible to mice and rats (at perimeter fence sites opposite pasture or forest habitat). We monitored sites using cameras and tracking cards within the fence hood and at tunnels at the fence base. Along the internal fence, mice were never observed within the hood but marked 40% of tunnels at the fence base. Along the perimeter fence, mice made four visits to the hood and marked 28% of tunnels at the fence base. Rats travelled exclusively within the fence hood (n = 42). Light did not reduce rat sightings but adjacent habitat affected their presence (forest > pasture; p ≤ 0.01). Positioning future ecosanctuary fencing alongside pasture and maintaining open corridors opposite fences at current ecosanctuaries may reduce rat presence.
Invasive mammals are a major threat to biodiversity. Understanding how their distributions and abundance could be affected by different temporal and spatial control strategies is fundamental for planning effective management programs.
We developed a spatially explicit, agent‐based model to test the impacts of different spatiotemporal management strategies on a pest population. As a case study, we used the common brushtail possum (Trichosurus vulpecula) population in the Cape‐to‐City treatment area in Hawke's Bay, New Zealand.
We found striking differences in the effectiveness of different spatial control strategies – a well designed spatial control strategy could be up to twice as cost effective as poorly designed ones.
The optimal spatial control strategy may depend on the total control effort. At low control effort, habitat‐targeted control was more effective; at high control effort, homogeneously distributed control was more effective.
Immigration rather than in situ breeding is likely to initiate the population recovery in treated areas after an initial knockdown. Therefore, increasing the size of treatment areas and maximizing the use of natural barriers to immigration could prolong treatment persistence.
Synthesis and applications. We have demonstrated how a spatially explicit, agent‐based model can be used to identify key criteria for a control strategy of open pest populations. The integration of available information on pest habitat use, population dynamics and actual levels of control allowed us to assess the deployment of control sites and assisted the choice of spatial control strategies. Important roles for this type of model are to help predict hotspots of mammalian pest activities, to suggest the most effective control strategy and to identify important parameters and data for improving predictions. Ultimately, further integration of spatial and temporal analyses is critical for updating and optimizing management strategies.
Determining pest mammal impacts and abundance in forests requires an understanding of how target species use vegetation compared with the ground. We used a novel device combining footprint tracking with bite detection to survey for mammals at four levels in New Zealand forests that had house mice (Mus musculus) alone, and all widespread New Zealand mammals, including house mice, ship rats (Rattus rattus) and brushtail possums (Trichosurus vulpecula). When alone, house mice were detected at 93%, 35%, 17% and 0% of devices on the ground, in shrubs, in the subcanopy and canopy, respectively, but in a pilot study at one site were detected 11 m above ground. When all small pest mammals were present, house mice were scarce and none were detected up trees. Ship rats and possums were detected mostly on the ground, but also at all surveyed heights. The study confirms that mice, ship rats and possums are all potential above-ground predators, but suggests that targeting them for control and monitoring can reasonably be undertaken on the ground.
Context The abundance and distribution of mammalian species often change in response to environmental variability, losses or gains in suitable habitat and, in the case of pest species, control programs. Consequently, conventional distribution maps rapidly become out of date and fail to provide useful information for wildlife managers. For invasive brushtail possum populations in New Zealand, the main causes of change are control programs by central and local government agencies, and post-control recovery through recolonisation and in situ recruitment. Managers need to know current, and likely future, possum population levels relative to control targets to help assess success at preventing the spread of disease or for protecting indigenous species. Information on the outcomes of government-funded possum control needs to be readily available to members of the general public interested in issues such as conservation, disease management and animal welfare. Aims To produce dynamic, scalable maps of the current and predicted future distribution and abundance of possums in New Zealand, taking into account changes due to control, and to use recent visualisation technology to make this information accessible to managers and the general public for assessing control strategies at multiple spatial scales. Methods We updated an existing individual-based spatial model of possum population dynamics, extending it to represent all individuals in a national population of up to 40 million. In addition, we created a prototype interface for interactive web-based presentation of the model's predictions. Key results The improved capability of the new model for assessing possum management at local-to-national scales provided for real-time, mapped updates and forecasts of the distribution and abundance of possums in New Zealand. The versatility of this platform was illustrated using scenarios for current and emerging issues in New Zealand. These are hypothetical incursions of possums, reinvasion of large areas cleared of possums, and impacts on animal welfare of national-scale management of possums as vectors of bovine tuberculosis (TB). Conclusions The new individual-based spatial model for possum populations in New Zealand demonstrated the utility of combining models of wildlife population dynamics with high-speed computing capability to provide up-to-date, easily accessible information on a species' distribution and abundance. Applications include predictions for future changes in response to incursions, reinvasion and large-scale possum control. Similar models can be used for other species for which there are suitable demographic data, typically pest species, harvested species or species with a high conservation value. Implications Models such as the spatial model for possums in New Zealand can provide platforms for (1) real-time visualisation of wildlife distribution and abundance, (2) reporting and assessing progress towards achieving management goals at multiple scales, (3) use as a decision-support tool to scope potential changes in wildlife populations or simulate the outcomes of alternative management strategies, and (4) making information about pest control publicly available.
Impact scoring schemes are useful for identifying to what extent alien species cause damage. Quantifying the similarity and differences between impact scoring schemes can help determine how to optimally use these tools for policy decisions. Using feral mammals (including rats and mice) as a case study, environmental and socio-economic impacts were assessed using three schemes, namely the Generic Impact Scoring System (GISS), Environmental Impact Classification for Alien Taxa (EICAT) and Socio-Economic Impact Classification for Alien Taxa (SEICAT). The results show that socio-economic impacts scores differ between the respective schemes (GISS and SEICAT) possibly because they assess different aspects of social life and economy. This suggests that both scoring schemes should ideally be applied in concert to get a complete picture of socio-economic impacts. In contrast, environmental impact scores are correlated between GISS and EICAT assessments and this similarity is consistent over most mechanisms except for predation and ecosystems, suggesting that one scoring scheme is sufficient to capture all the environmental impacts. Furthermore, we present evidence for the island susceptibility hypothesis as impacts of feral mammals were found to be higher on islands compared to mainlands.
Context. The risk of secondary poisoning to native fauna during pest control operations is an issue of global concern. In New Zealand, non-target impacts during sodium fluoroacetate (1080) operations are particularly contentious. 1080 is used extensively for pest control for conservation, bovine tuberculosis control, and in plantation forestry for seedling protection from herbivores. The endemic New Zealand falcon (Falco novaeseelandiae) breeds in Kaingaroa forest, an intensively managed pine plantation where regular 1080 poison operations are conducted; however, causes of mortality and risks of secondary poisoning by 1080 are not well documented. Aims. We aimed to investigate mortality and survival of adult falcons with an emphasis on assessing the possible role of 1080 poisoning in annual mortality. Methods. Using radio-telemetry and visual observations, we monitored 37 marked adult falcons before and after 1080 operations in 2013-14 (16 through carrot-bait and 21 through cereal-bait operations) and assessed mortality causes through post-mortem examinations. Using Program MARK, the annual survival rates for adults and independent juveniles were estimated from long-term banding data (2003-2014). Key results. Survival of falcons was high through both cereal-bait (21/21) and carrot-bait (15/16) 1080 operations (overall 95%CI for survival = 84-100%). The exception was a radio-tagged male that died of unknown causes within a fortnight of an operation and tested negative for 1080 residues. Three falcons were depredated by introduced mammals. One falcon was found dead in an emaciated condition but evidently died from head injury through Australasian magpie (Cracticus tibicen) attack. The annual survival rate of falcons estimated from long-term banding was 806.0% (means.e.) for adults and 290.1% for juveniles. Conclusions. No adult falcon death was attributable to 1080 poisoning in this study. Identifiable mortalities were attributable to depredation by introduced mammals and an injury from an Australasian magpie. The annual survival rate of Kaingaroa falcons was comparable to those of other raptor species worldwide. Implications. The risk to adult falcons from 1080 secondary poisoning is likely low. Whether this is also true for juveniles requires further study.
Deforestation and conversion to intensive agriculture historically caused a large reduction in numbers of the New Zealand falcon or Kārearea (Falco novaeseelandiae), resulting in its current classification as Nationally Vulnerable. Several studies in plantation forests have documented the ecological benefits of limited timber harvesting on diversities of avian species through providing habitat heterogeneity. New Zealand falcons occur in managed plantation forests. To date, however, detailed information regarding falcon prey abundance, habitat use, home-range size, and breeding behaviour has been limited to their breeding season. Little is known about their winter use of managed forests and how forest operations affect their survival and reproductive ability by restricting their mating system.
I investigated a falcon population living in a large plantation forest, Kaingaroa forest through addressing the following questions: (1) how changes in forest structures influence falcons’ habitat use and home-range size in relation to winter prey abundance and availability, (2) how the reduction in habitat heterogeneity by large-scale harvesting affects falcon’s home-range size and overlap, (3) the risk of secondary poisoning from 1080 operations and falcon annual survival, and (4) how constraints by changes in the forest structure and compositions shape the mating system of the Kaingaroa falcon population. I used radio-tracking data to establish the extent and habitat composition of winter home-ranges, and monitoring survival of falcons before and after 1080 poisoning operations. I used transect surveys to assess the availability of potential prey birds, and behavioural observation to measure pair breeding activities.
I found that falcons used the ecotone between mature-pine stands and young-pine stands (the edge-habitat) most frequently followed by their hunting ground (young-pine stands – 0–3-year-old pine trees). Total prey abundance was similar across all habitats and sizes of open fields. The dynamic changes to forest structure created by clear-cutting and its effect on prey accessibility are the most profound factor influencing falcon space use. Winter home-range sizes of forest falcons (used Kaingaroa exclusively) were smaller than those of farmland falcons, which used farmland > 10 % of total tracking duration. I found that falcons used smaller home ranges when the forest provided the edge-habitats that were concentrated among mature-pine stands through creating open-patches less than 3 km2 that are distributed closely (< 3 km apart). Results indicate that timber forests could hold a greater number of falcons with these forest compositions.
Sixteen adult falcons were potentially exposed to 1080-affected prey during carrot-bait ground operations during the three winter months (May–August), and all bar one survived. The exception was a radio-tagged male that died within a fortnight of the 2014 operation, of unknown cause. Additionally, 21 marked adult falcons were potentially exposed to 1080-affected prey from cereal-bait aerial operations in February 2013 and November 2014; all survived. The survival rate of adult Kaingaroa falcons was 80% and that of juveniles was 29%.
All divorces (40%) were initiated by females leaving their territories regardless of reproductive outcomes, while males exhibited greater mate and site fidelity. A high rate of extra-pair interaction occurred by females (71%) but was absent in males. Female’s extra-pair interaction implemented as their strategy for securing breeding opportunities. In contrast, the mate-guarding strategy may be the most effective male’s mating strategy in the Kaingaroa falcon population. Male’s vigilant personality likely enhanced mate-guarding performance. Home-range overlap was greater in pairs that retained partners than pairs that divorced. Winter courtship displays were used for pair formation (the process of establishing a social bond) rather than pair bonding (the process of maintaining a social bond), and also used for intra-sexual competition over females. A rapid rotation of habitat quality and sufficient prey availability in the area may shape falcons’ various mating systems.
A further long-term continual monitoring that includes the juvenile falcons is required to measure the effects of 1080 poison on the Kaingaroa falcon population. A well-designed harvesting regime could enable the timber industry to contribute importantly to the conservation of this threatened New Zealand raptor.
Kokako was widespread in the study area in 1980-81 but its range is continuing to shrink. The status of many populations is still uncertain. Kokako appear to have disappeared recently from large forest tracts in SE and inland Taranaki and from large isolated forests in the north. Most kokako were in unmodified rimu-tawa dominant forest. Habitat deterioration appears to be an important factor in their decline. -from Author
Used wisely, sodium monofluoroacetate (1080) is a highly effective toxin for large-area control of introduced mammal pests in New Zealand. However, behavioural resistance to 1080 can develop in pest populations that are exposed repeatedly to the toxin through sustained control programmes. Rabbits (Oryctolagus cuniculus) in some heavily-poisoned areas now exhibit innate neophobia towards both toxic and non-toxic baits. Very few possums (Trichosurus vulpecula) are neophobic, but two field experiments suggest that behavioural resistance can arise in this species through learned aversion to toxic bait caused by sublethal dosing. For example, attempts at 1080 control of two possum populations exposed several months earlier to sublethal doses reduced the populations by only 20% and 7%, respectively. Behavioural resistance is a significant threat to the efficacy of sustained control and should be addressed explicitly in pest management plans.
The diet of the North Island kokako (Callaeas cinerea wilsoni) was studied in three central North Island habitats, Pureora, Mapara, and Rotoehu, for three years. Possum (Trichosurus vulpecula) diet was less intensively studied for part of the same time in Pureora and Mapara. A literature review was made of the diet of possum, red deer (Cervus elaphus), and feral goat (Capra hircus). There is considerable overlap between the diets of kokako and the three mammalian browsers; leaves and/or fruit of some species are eaten by all four, e.g. mahoe (Melicytus ramiflorus), fivefinger (Pseudopanax arboreus), lawyer (Rubus cissoides), pigeonwood (Hedycarya arborea), and raurekau (Coprosma australis). Possums, red deer, and goats have reduced the abundance of preferred kokako food plants in much of the remaining kokako habitat. The present distribution of kokako suggests that their decline has been caused not only by forest clearance and introduced predators, but also by impoverishment of habitat resulting from the introduction of browsing mammals.
We radio‐tracked five male and four female rats for 6 nights in primary forest at Rotoehu, North Island. New Zealand. From trapping we estimated rat density at the study site to be 6.2 rats/ha. Radio‐tracking revealed mean (± SE) restricted polygon home ranges to be three times greater in males (1.1 ± 0.29 ha) than females (0.3 ± 0.04 ha). Male ranges overlapped considerably, whereas those of females were largely exclusive. The ranges of males encompassed several female ranges. Four radio‐collared rats were retrapped and administered a lethal dose of the anticoagulant poison brodifacoum. During the 3–5 nights after poisoning but before death, we detected no significant change in home range area or utilisation, arboreality, or movements. Further research is required to determine if rats prey on other fauna while fatally intoxicated or cause secondary poisoning after being eaten by other predator species.
Systematic direct observations of the small, fast‐moving, and wide‐ranging stoat are rarely practicable. The simplest indirect methods of observation are kill‐trapping, live‐trapping, and footprint recording. The data obtainable and the advantages and disadvantages of these methods are reviewed. Two new kinds of traps and a footprint recording system are described; they are especially suitable for use in rugged field conditions far from base facilities. When operated together in suitable habitat, these techniques can provide useful information on the population structure, feeding habits, and natural movements of stoats. Together or singly they also have potential as management tools, especially in identification of nest predators and in faunal surveys of islands.
Even unmanaged ecosystems are characterized by combinations of stability and instability and by unexpected shifts in behavior from both internal and external causes. That is even more true of ecosystems managed for the production of food or fiber. Data are sparse, knowledge of processes limited, and the act of management changes the system being managed. Surprise and change is inevitable. Here we review methods to develop, screen, and evaluate alternatives in a process where management itself becomes partner with science by designing probes that produce updated understanding as well as economic product.
The abundance and diet of stoats (Mustela erminea) were compared before and after an aerial 1080- poison operation for possums (Trichosurus vulpecula) in a New Zealand podocarp-hardwood forest. Poisoning dramatically reduced ship rat (Rattus rattus) abundance. Although rats were the main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet from rats to birds. The conservation benefits and risks of undertaking such operations are not clear. It is not known whether the predation risk for any particular species of bird (or other animal) will be higher or lower with fewer rats but the same density of stoats; As large-scale poison operations are now common in New Zealand forests, a better understanding of predator-prey relationships in these areas is required as soon as possible.
Kiwi have declined markedly in abundance and range since human settlement of New Zealand. Three of the four species are still extant in mainland forests, despite decades of co-existence with various introduced mammals. Little spotted kiwi is now probably confined to offshore islands. The role of introduced mammals in these population declines was evaluated by measuring the survival rates of adults, eggs and chicks of brown kiwi (A. mantelli) and great spotted kiwi (A. haastii) in mainland forests. Mortality rates of adults ranged from 5%-16% and did not differ significantly between species or sexes. Overall, 14 out of 209 adult kiwi died during 159.6 radio-tracking years. Predators definitely caused five of these deaths. Sixty-nine (68%) of 102 eggs from 77 nesting attempts by 48 pairs failed to hatch. Predators probably caused about 10% of egg failures. Only three of 49 chicks probably survived to adulthood, indicating a juvenile mortality rate of about 94%. Predators killed at least 8% of chicks, 45% of juveniles, and possibly as many as 60% of all young kiwi. Ferrets and dogs were the main predators of adult kiwi, possums and mustelids were the main egg predators, while stoats and cats were largely responsible for the deaths of young kiwi. Population models show that northern brown kiwi are currently declining at 5.8% per annum. This decline could be halted by cutting the current predation rates on young kiwi by about 34% to 33%.
The impacts of the two most widespread introduced herbivores in New
Zealand (red deer and possums) were investigated to compare the relative
importance of arboreal and terrestrial browsers, and to determine the likely
relationships between pest density and their impacts. The study was conducted
between 1990 and 1993 in podocarp-hardwood forest west of Lake Taupo,
where the density, diet, and forage use of the two species was quantified and
compared with quantitative estimates of forest composition, forage availability
and production, and stem diameter and seedling height distributions. Deer
density was stable at about c. 6 deer/km2
, and annual faecal output for deer was
estimated at 14 kg (dry weight)/ha/yr. Possum density increased during the
study to reach c. 3 possums/ha in 1993, with an estimated faecal output of 44
kg/ha/yr for that year. In the forest, pepperwood (Pseudowintera colorata)
and Neomyrtus pedunculata were most abundant, but podocarps comprised
nearly half the total basal area of 73 m2
/ha. About 2.5 tonnes/ha of foliage were
produced annually, suggesting that c. 5 tonnes/ha of foliage were available to
possums. In contrast, only 288 kg/ha of forage was available within the deer
browse tier with just 9 kg/ha of that being comprised of the seven foods most
important to deer. Deer and possums ate much the same range of about 100
plant species, but there was very little overlap in the main food used by each
species. For deer, woody plants comprised 70% of the annual diet, ferns 17%,
and grasses 10%, with broadleaf (Griselinia littoralis) and lancewood
(Pseudopanax crassifolius) being the two most important foods. Most deer
forage consisted of adult tree foliage, much of it obtained as litterfall. Woody
plants also predominated (c. 80%) in possum diet, followed by herbs and ferns
(c. 5% each). Possums relied heavily on fruit at times, but the foliage of Hall’s
totara (Podocarpus hallii) was their main food. Overall, possums and deer
consumed about 88 and 30 kg of forage/ha/yr, respectively, equating to 3.3% of
total annual foliage production (AFP) for possums and just 1.1% of AFP for deer.
Possums used 16 of the 40 most common species or species groups, but ate
less than 12% of AFP for all but three of those. Deer consumed far greater
proportions of the much smaller quantities of AFP available to them and, as a
consequence, prevented regeneration for many of their preferred species. In
contrast, possums appeared to have relatively little influence on the seedling
heights (i.e., regeneration) of common species. Overall, there appeared to be
little competition for food between the species, and possum impacts were
focused on fewer woody plants than were deer impacts. Deer had a greater
impact on regeneration patterns within the browse tier than did possums on
the forest as a whole. Because neither species removed much of the total
annual foliage production, major dieback or changes in abundance of the most
common species appeared unlikely. However, most podocarps (excluding
Hall’s totara) and other unpalatable species appeared likely to increase and
many of the palatable species likely to decrease while deer and possums
remained uncontrolled. A major reduction in deer density (i.e., to <2 deer/km2
)
would be required to significantly alter present regeneration patterns. If deer
numbers remain above this level, intensive possum control would have little
6
effect on regeneration patterns, but should benefit established specimens of
Hall’s totara and other possum-preferred species not accessible to deer. These
results suggest the Department of Conservation should reassess present
priorities in possum and ungulate (deer and goat) control for vegetation
protection, giving greater consideration to the dominant influence of ungulates
on patterns of ground-level regeneration.
Two scientific methods called induction and retroduction form the basis for almost all wildlife research. Induction is used to establish reliable associations among sets of facts, whereas retroduction is used to establish research hypotheses about the fact-giving processes driving nature. A 3rd scientific method, the hypothetico-deductive (H-D), is a means for testing research hypotheses, i.e., for gauging their reliability. The H-D method is rarely used in wildlife science. Instead, research hypotheses are proposed, and either made into a law through verbal repetition or lose favor and are forgotten. I develop the thesis that wildlife research should use the H-D method to test research hypotheses, using the threshold- of-security hypothesis for winter mortality for illustration. I show that persistent confusions about the definitions of concepts like carrying capacity, correlation and cause-and-effect, and the reliability of know 1- edge gained from computer simulation models stem from either inadequate or misused scientific methods.
The fifteen contributions show the formidable difficulties inherent in predicting the consequences of ecosystem changes, noting the use but also limitations of historical records and simulation models. The way forward is envisioned as being through long-term experimental manipulation of whole ecosystems. Such experiments would not only show how whole sytems, as well as their component elements, might respond to both short- and long-term change, but would also serve as tests for simulation models. Chapters, all abstracted separately, are on: El Nino; atmosphere-forest interactions and Amazon Basin deforestation; lessons from deforestation processes in the past; desertification; acid rain and forest ecosystems; uncontrolled ecosystem experiments with inorganic and organic micropollution; whole-lake experiments at the Experimental Lakes Area; fire and stream water chemistry; acidification; wetland ecosystems; forested watershed disturbance; mathematics of complex systems; aquatic ecosystem experiments in the context of global climatic change; whole-terrestrial ecosystem experiments; available technologies for field experimentation with elevated CO2 in global change research. (See 93L/11129, 11130, 11318, 11319, 11447-11449, 11453, 12022, 12064, 12065, 12109, 12200 and 12251). -P.J.Jarvis
Heritable reproductive strategies that yield the greatest lifetime production of surviving offspring are favored by natural selection. I consider a reproductive strategy to be the complement of behaviors and traits associated with reproduction that influence lifetime reproductive success. Trade-offs among standard life history traits (e.g., clutch size, growth rate, juvenile and adult mortality) influence success of reproductive strategies (see reviews by Stearns, 1976; Martin, 1987). In addition, energy allocation between reproduction and other activities can influence expression of traits such as clutch size (Cody 1966). However, for organisms that care for their young, success of traits is also strongly affected by the amount of energy and time allocated to care of young by parents (Trivers, 1972, 1974; Low, 1978; Clutton-Brock, 1984). In other words, allocation of energy and time among different activities within reproduction can be as important as allocation between reproduction and other activities.
Callaeas cinerea wilsoni fed mainly from branches and twigs of canopy and upper-understorey plants. ALthough 68 different foods were eaten, only 8 contributed >5% to the observed diet in any season. The diet consisted of fruit (44%), unknown foods (18%), leaves (15%), epiphytes (11%), invertebrates (8%), buds (2%), flowers (1%) and nectar (1%). Use of these food-types varied seasonally. Fruit consumption was high in summer, autumn and winter; invertebrates were taken mainly in spring. Kokako ate leaves, including those of epiphytes, most often in winter and least often in summer. When epiphytes, lianes and invertebrates are included with their host trees, kokako obtained most food from shrub hardwoods (54%). Use of the other vegetation types for food was: tree hardwoods (30%); podocarps (14%); ground-storey plants (1%); and tree ferns (1%). Kokako fed mainly between the crown foliage of canopy trees and 3 m from the ground, where shrub hardwoods and much of the foliage of tree hardwoods and epiphytes predominated. -from Author
We analyze perturbation experiments performed on real and ealized ecological communities. A community may be considered as a black box in the sense that the individual species grow and interact in complicated ways that are difficult to discern. Yet, by observing the response (output) of the system to natural or human-induced disturbances (inputs), information can be gained regarding the character and strengths of species interactions. We decline a perturbation as selective alteration of the density of one or more members of the community, and we distinguish two quite different kinds of perturbations. A PULSE perturbation is a relatively instantaneous alteration of species numbers, after which the system is studied as it @'relaxes@' back to its previous equilibrium state. A PRESS perturbation is a sustained alteration of species densities (often a complete elimination of particular species): it is maintained until the unperturbed species reach a new equilibrium. The measure of interest in PRESS perturbation is the net change in densities of the unperturbed species. There is a very important difference between these two approaches: PULSE experiments yield information only on direct interactions (e.g. terms in the interaction matrix), while PRESS experiments yield information on direct interactions mixed together with the indirect effects mediated through other species in the community. We develop mathematical techniques that yield measures of ecological interaction between species from both types of experimental designs. Particular caution must be exercised in interpreting results form PRESS experiments, particularly when some species are lumped into functional categories and others are neglected altogether in the experimental design. We also suggest mathematical methods to deal with temporal and random variation during experiments. Finally, we critically review techniques that rely on natural variation in numbers to estimate species interaction coefficients. The problems with such studies are formidable.
The introduction of alien species to New Zealand's terrestrial ecosystems has caused rapid loss of native biodiversity since human settlement. Faced with this crisis, conservation managers and scientists have responded by developing innovative techniques such as translocation of native animals and the eradication of introduced mammals from islands. We review recent progress with conservation of New Zealand's terrestrial flora and fauna (especially birds) and consider future prospects for ecological restoration of islands and mainland areas. We stress the value of linking species and ecosystem approaches to conservation and we reinforce the importance of maintaining a dynamic partnership between researchers and conservation managers in the development of conservation initiatives.
Two Placostylus ambagiosus populations were studied in New Zealand for 8 years to determine if poisoning rodent predators in the habitat of one population resulted in increased adult snail recruitment. ‘Pulse’ poisoning four times a year commenced a year after the study started in a population of Placostylus ambagiosus paraspiritus. A significant increase in the proportions of all juvenile snails with shells larger than 10 mm long was observed. The only other comparable population of this highly endangered snail species, P. a. michiei, was 33·7 km to the east. Here, predation mostly by birds had a similar effect on reducing adult snail recruitment as rodents did on P. a. paraspiritus. No predator control was done at the site occupied by P. a. michiei, and adult snail recruitment remained low throughout the study. This suggests that long-term pulse poisoning of rodents in remnant ‘islands’ of native habitat on the New Zealand mainland can be beneficial to the recovery of a landsnail population.
Press perturbation experiments, in which individuals of a particular species are continually added to or removed from an ecosystem and the responses of other species' densities are observed, are discussed in the context of whole systems. When the sizes of direct interactions are determined to within an order of magnitude, long-term outcomes of press perturbations are highly indeterminate in terms both of whether species densities increase or decrease and of which interactions have the largest effects. Short-term observations of systems subject to press perturbations. are not useful for estimating long-term impacts. -from Author
This paper describes the impact of nine poison operations on ship rats in four areas (35 ha to 3200 ha) of North Island forest. Poisoning with 1080, brodifacoum, or pindone killed 87-100% of rats, based on trapping and tracking-tunnel indices. Rat populations took 4-5 months to recover. Operations to protect nesting birds should therefore coincide with the onset of nesting and be repeated each year, although not necessarily with the same methods. Population reduction declined each year at Mapara, King Country, during three annual 1080 operations which used the same lures and baits, but remained high at Kaharoa, Bay of Plenty, where poison toxicity was higher, non-toxic bait was pre-fed, and poisoning methods varied each year. Mouse tracking rates increased in poisoned forests 3-6 months after poisoning if the initial kill of rats exceeded 90%, peaked 7-9 months after poisoning, then declined to pre-poison levels. Future research should focus on how prey and non-prey species within a forest community respond to a temporary reduction in rat numbers, and on methods to maintain low rat densities after initial knock-down.
A poisoning operation using Talon 20P™, active ingredient brodifacoum, targeting rabbits (Oiyctolagus cuniculus) in coastal grasslands on the Otago Peninsula, New Zealand, also killed stoats (Mustela erminea), ferrets (Mustela furo), cats (Felis catus), and mice (Mus musculus) and probably possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus), rats (Rattus rattus), hares (Lepus europaeus occidentalis), and chaffinches (Fringilla coelebs). A new immigrant ferret also died 41 days after poisoning. If repeated in other habitats such as tussock grasslands and forests this method could greatly assist in restoration of mainland ecosystems and mitigation of bovine tuberculosis (Mycobacterium bovis) by controlling a variety of pests/ Tb carriers in one operation. The removal of small mammalian predators following poisoning operations could decrease immediate predation pressure on native wildlife. However, the efficacy of this multi‐species pest control method and unwanted side‐effects must be researched before its routine use. This research also demonstrates the potential threat of second‐generation anticoagulant poisons such as brodifacoum to small mammalian carnivores with high conservation value in their native countries.
Brushtail possums (Trichosurus vulpecula) were offered Japanese quail (Coturnix japonica) eggs and day-old domestic chickens (Gallus gallus) during a captive feeding trial. Differences in feeding sign left by possums of differing sex, age class, and hunger were slight or absent. Possum feeding trial remains were also compared with remains of North Island robin (Petroica australis longipes) and North Island tomtit (Petroica macrocephala toitoi) eggs and chicks preyed on by ship rats (Rattus rattus) at videoed nests. Eggs fed on by possums were frequently crushed or had crushed shell margins whereas eggs preyed on by ship rats often had jagged shell margins and separate small shell fragments. Possums that ate chickens mostly left partially eaten carcasses with torn flesh, of which 50% were at least partially skinned. Ship rats left partially eaten birds with chewed flesh and bones but did not skin carcases. Possums rarely spat out shell pellets but produced feather pellets on eight of 13 occasions. Egg shell remains left by possums were indistinguishable from those left by ship rats for 11% of 72 shell remains examined from the feeding trial. Characteristic sign should enable possums and ship rats to be differentiated as predators after most but not all predations.
This book is about ways of dealing with uncertainty in the management of renewable resources, such as fisheries and wildlife. The author's basic theme is that management should be viewed as an adaptive process: one learns about the potentials of natural populations to sustain harvesting mainly through experience with management itself, rather than through basic research or the development of general ecological theory. The need for an adaptive view of management has become increasingly obvious over the last two decades, as management has turned more often to quantitative model building as a tool for prediction of responses to alternative harvesting policies. The model building has not been particularly successful, and it keeps drawing attention to key uncertainties that are not being resolved through normal techniques of scientific investigation. The author's major conclusion is that actively adaptive, probing, deliberately experimental policies should indeed be a basic part of renewable resource management.
Recent suggestions for experimental tests of current hypotheses about populations deserve attention by field biologists and wildlife managers. A ready-made opportunity for the level of replication needed for bona fide statistical tests exists in the multiple management areas used in most states. Simple difference equation models might be used directly as null hypotheses. More complex models involving interactions of animal populations and food supplies require more study before suitable designs can be prepared. Such evaluations can likely be done retrospectively, using available data, and require vigorous and continuing discussions among biologists.
The addition of nest predation as a major process to current theories of space utilization and coexistence of open-nesting bird species adds predictive power to hypotheses of resource partitioning and organization of species assemblages. Nest predation can influence the organization of assemblages if predators respond to nests in a density-dependent manner and if predators specialize on nest types. Evidence shows that nest predation is commonly density-dependent and that predators can specialize on nest types. Consequently, nest predation can select for coexistence of bird species that nest at different heights and in different microhabitats (i.e. partitioning of nesting space) to minimize density-dependent responses of predators to the accumulating densities of species within similar nest sites. I establish a series of predicted patterns (1) to test whether predation is operating to influence partitioning of space and coexistence of species, (2) to distinguish effects of nest predation from competition, and (3) to determine the mechanism by which nest predation acts to organize assemblages. Using published and unpublished data to test the predictions, nest predation is seen as a process that we can no longer afford to ignore.
Focusing on birds with altricial young, and in the context of an energy allocation framework based on life history theory, the author considers egg production (egg size and quality, the trade-off between egg quality and number, and evidence for food limits on egg production); incubation; the nestling period (hatching pattern, growth rate, and brood size); the post-fledging stage; and reproductive costs on parents (timing and cause of energy stress, and effects of food limitation on parents). Final comments look at dominance and winter survival.-P.J.Jarvis
This paper reports the results of a survey of the physical and mental reactions of a group (N= 72) of members of the South Australian Metropolitan Fire Service (MFS) who were engaged in fighting the bushfires close to Adelaide, 16th-19th February 1983. A questionnaire, designed to elicit reports on both physical and mental reactions to exposure to the fire, as well as perceptions of several measures of social strain and social support, was administered to the firefighters when they came off duty. The results reported show the possible influence of role strain factors in predicting mental reactions, and also demonstrate what may be mediating effects of perceived social support. The paper also discusses methodological problems affecting this and other studies of the reactions of emergency service personnel to disaster.
Fates of kokako nesting attempts at (a) Rotoehu (1989±1994, n=65). and (b) Mapara
- Fig
Fig. 6. Fates of kokako nesting attempts at (a) Rotoehu (1989±1994, n=65). and (b) Mapara (1991±1997, n=116).
The New Zealand wattlebirds (Callaeatidae)
- G R Williams
Williams, G.R., 1976. The New Zealand wattlebirds (Callaeatidae). In: Frith, H.J., Calaby, J.H. (Eds.), Proceedings of the 16th Interna-tional Ornithological Congress. Australian Academy of Science, Canberra, pp. 161±170.
Conservation of New Zealand forest birds: the next decade
- M N Clout
Clout, M.N., 1989. Conservation of New Zealand forest birds: the next decade. In: Norton, D.A. (Ed.), Management of New Zeal-and's Natural Estate. New Zealand Ecological Society Occasional Publication 1, Wellington, pp. 59±61.
Mapara: Island management “mainland” style
- A Saunders
Saunders, A., 1990. Mapara: Island management mainland'' style.
Population ecology of ship and Norway rats in New Zealand The ecology and control of rodents in New Zealand nature reserves. Departments of Lands and Survey Information Series Testing hypotheses about populations
- M J Daniel
Daniel, M.J., 1978. Population ecology of ship and Norway rats in New Zealand. In: Dingwall, P.R., Atkinson, I.A.E. and Hay, C. (Eds.), The ecology and control of rodents in New Zealand nature reserves. Departments of Lands and Survey Information Series 4, Wellington, pp. 145±152. Eberhardt, L.L., 1988. Testing hypotheses about populations. Journal of Wildlife Management 52, 50±56.
Population size and breed-ing success of North Island kokako in the Waipapa Ecological Area. Pureora Forest Park Breeding of kokako
- D Meenken
- T Fechney
- J Innes
Meenken, D., Fechney, T., Innes, J., 1994. Population size and breed-ing success of North Island kokako in the Waipapa Ecological Area. Pureora Forest Park. Notornis 41, 109±115. McKenzie, H.R.., 1951. Breeding of kokako. Notornis 4, 70±76.
The potential impact of predator control on survival of kokako populations in reserves The nesting of the North Island kokako (Callaeas cinerea wilsoni)Ðreview of accounts from 1880 to 1989 A time-lapse video camera system for detecting predators at nests of forest birds: a trial with NI kokako
- C Imboden
- J Innes
- J R Hay
- J Innes
- J R Hay
Imboden, C., 1978. Wildlife values and wildlife conservation in the Hauhungaroa and Rangitoto Ranges. Fauna Survey Unit Report 10, NZ. Wildlife Service, Wellington. Innes, J., Hay, J.R., 1985. The potential impact of predator control on survival of kokako populations in reserves. New Zealand Journal of Ecology 8, 149. Innes, J., Hay, J.R., 1995. The nesting of the North Island kokako (Callaeas cinerea wilsoni)Ðreview of accounts from 1880 to 1989. Notornis 42, 79±93. Innes, J., Crook, B., Jansen, P., 1994. A time-lapse video camera system for detecting predators at nests of forest birds: a trial with NI kokako. In: Bishop, I. (ed.), Proceedings of the Resource J. Innes et al./Biological Conservation 87 (1999) 201±214 Technology '94 Conference. University of Melbourne, Australia, pp. 439±448.
Changes in Mapara Wildlife Reserve Forests 1989-1995. Unpublished report. NZ Department of Conservation
- P Corson
Corson, P., 1997. Changes in Mapara Wildlife Reserve Forests 1989± 1995. Unpublished report. NZ Department of Conservation, Hamilton.
Brushtail possum The handbook of New Zealand Mammals
- P E Cowan
Cowan, P.E., 1990. Brushtail possum. In: King C.M. (Ed.), The handbook of New Zealand Mammals. Oxford University Press, Auckland, pp. 68±98.
Kokako (Callaeas cinerea) in the Hunua Range Behavioural resistance by vertebrate pests to 1080 toxin: implications for sustainable pest management in New Zealand
- A E Fitzgerald
Fitzgerald, A.E., 1984. Diet overlap between kokako and the common brushtail possum in central North Island, New Zealand. In: Smith, A.P. and Hume, I.D. (Eds.), Possums and gliders. Australian Mammal Society, Sydney, pp. 569±573. Greene, B.S., 1995. Kokako (Callaeas cinerea) in the Hunua Range, Auckland, 1992±94. Notornis 42, 11±16. Hay, J.R., 1984. The kokakoÐperspective and prospect. Forest and Bird 15, 6±11. Hickling, G.J., 1994. Behavioural resistance by vertebrate pests to 1080 toxin: implications for sustainable pest management in New Zealand. In: Seawright, A.A. and Eason, C.T. (Eds.), Proceedings of the science workshop on 1080. The Royal Society of New Zeal-and Miscellaneous Series, vol. 28, pp. 151±171. The Royal Society of New Zealand, Wellington.
Swamp harrier. In: Hand-book of Australian
- S Marchant
- P J Higgins
Marchant, S., Higgins, P.J., (Eds.), 1993. Swamp harrier. In: Hand-book of Australian, New Zealand and Antarctic Birds, vol. 2, raptors to lapwings. Oxford University Press, Melbourne, pp. 105±122.
The foods, foraging behaviour and habitat use of North Island kokako in Puketi State Forest Bait shyness and poison aversion Rodent Pest Management Recovery plan for North Island kokako Wildlife science: gaining reliable knowledge
- R G Powlesland
Powlesland, R.G., 1987. The foods, foraging behaviour and habitat use of North Island kokako in Puketi State Forest, Northland. New Zealand Journal of Ecology 10, 117±128. Prakash, I., 1988. Bait shyness and poison aversion. In: Prakash, I. (Ed.), Rodent Pest Management. CRC Press, Boca Raton, FL, pp. 321±329. Rasch, G., 1992. Recovery plan for North Island kokako. Threatened Species Recovery Plan, vol. 1. NZ Department of Conservation, Wellington. Romesburg, H.C., 1981. Wildlife science: gaining reliable knowledge. Journal of Wildlife Management 45, 293±313.