No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
The end of an 80-million year experiment: A review of evidence describing the impact of introduced rodents on New Zealand's 'mammal-free' invertebrate fauna
Abstract
Since separating from its super-continental origin 80million years ago, New Zealand has effectively been isolated from the
impacts of terrestrial mammals. The arrival of Polynesians in 13th C heralded the end of this era, with the introduction of
kiore, (Rattus exulans, or Pacific rat), which had far-reaching effects on plant regeneration, survival of small ground vertebrates, larger invertebrates,
and seabird breeding colonies. This paper reviews the evidence available from raptor nest sites and Quaternary beetle fossils
to summarise extinctions thought to be caused by kiore in New Zealand. It also utilises invertebrate comparisons between islands
with and without rats, or where rats have been eradicated, in order to document the impacts of rats (R. exulans, R. norvegicus) on invertebrate abundance, body mass, and the behavioural responses of some large New Zealand insects to the presence of
rats. The role of a ‘mammal-free’ evolutionary history is discussed.
... Vol.: (0123456789) Native invertebrate populations have been supressed by invasive rodents and some species have likely been driven to extinction on islands globally, though explicitly linking invertebrate extinctions with rodent predation is often difficult (St Clair 2011). Arthropods in the orders Coleoptera and Orthoptera and terrestrial snails are the primary taxa known to have been suppressed and extirpated by invasive rodents, and larger bodied invertebrates are particularly vulnerable (Gibbs 2009;St Clair 2011). Limited information on island invertebrate communities exists from before rodents were introduced; however, several studies show dramatic increases in abundance of invertebrates after rodent eradication and through comparisons of islands with and without rodents (Gibbs 2009;St Clair 2011;St Clair et al. 2011;Jones et al. 2016). ...
... Arthropods in the orders Coleoptera and Orthoptera and terrestrial snails are the primary taxa known to have been suppressed and extirpated by invasive rodents, and larger bodied invertebrates are particularly vulnerable (Gibbs 2009;St Clair 2011). Limited information on island invertebrate communities exists from before rodents were introduced; however, several studies show dramatic increases in abundance of invertebrates after rodent eradication and through comparisons of islands with and without rodents (Gibbs 2009;St Clair 2011;St Clair et al. 2011;Jones et al. 2016). This suggests that rodent predation can have a large negative impact on island invertebrates, particularly on island communities that evolved without terrestrial mammalian predators (e.g. ...
... This suggests that rodent predation can have a large negative impact on island invertebrates, particularly on island communities that evolved without terrestrial mammalian predators (e.g. New Zealand, Hawaiʻi, Seychelles, Balearic, and Canary Islands, Gibbs 2009;Traveset et al. 2009;St Clair 2011). ...
Rodents are among the most widespread and problematic invasive animals on islands worldwide contributing to declining endemic island biota through predation and disruption of mutualisms. Identifying what rodents eat is critically important to understanding their effects on ecosystems. We used DNA metabarcoding to identify the diets of three invasive rodents in Hawaiian forests: house mouse (Mus musculus), black rat (Rattus rattus), and Pacific rat (Rattus exulans). These rodents primarily eat invertebrates and plants, but previous diet studies have provided only a limited understanding of the diet breadth by relying on morphological identification methods. We opportunistically collected fecal samples from rodents trapped at seven forest sites across Oʻahu, Hawaiʻi for two years. Plant and invertebrate diet items were identified from DNA extracted from fecal samples using rbcL and COI primers, respectively. Intact seeds were identified using a dissecting microscope to quantify potential contributions to seed dispersal. All rodent species ate primarily plants and invertebrates of introduced species. However, some native taxa of conservation importance were identified. Neither the rodent species nor the sites drove patterns of diet composition, suggesting that diet variation may be determined by opportunistic foraging or intraspecific variation. Black rat fecal samples contained intact seeds more frequently than house mouse samples, but surprisingly, when samples contained seeds, black rats and house mice both defecated hundreds of introduced seeds, likely contributing to seed dispersal. Conservation efforts targeting invasive rodent control should specifically include house mice and should monitor introduced prey items to prevent predation release of unwanted introduced species.
... Introduced mammals are deleterious within the New Zealand context because the biota evolved in the absence of mammals except for three species of bat. Rodents are particularly harmful to both native flora and fauna (Gibbs 2009;Innes et al. 2010;Ramsay 1978) and, in New Zealand, they are controlled effectively primarily by poisoning and less frequently by snap-trapping (e.g. Thomas and Taylor 2002;Brown et al. 2015). ...
... The effects of rodents on vegetation are generally long-term (by destroying seeds and fruits 1 3 etc) whereas their negative effects are more immediately apparent on birds (by predation on eggs and chicks) and lizards. Rats are generally considered to have negative effects on an extensive range of invertebrates, especially large bodied ones and flightless insects (Towns et al. 2006;Gibbs 2009;Rate 2009;Watts et al. 2012;Barker 2016). ...
... Tree wētā are mostly herbivorous, feeding mainly on leaves, flowers, fruits, and seeds of a wide variety of plant species (Meads 1990;Green 2002;Duthie et al. 2006;Gibbs 2009;Wehi and Hicks 2010;Wyman et al. 2010;Griffin et al. 2011). They will, however, also opportunistically consume live and dead animals (Little 1980;Barrett 1991;Gibbs 2001). ...
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.
... The Pacific rat came along with Polynesian explorers, in the thirteenth century, and the Norway rat and Ship rat arrived with European colonists in the nineteenth century (Wilmshurst et al. 2008). Rodents, and other mammalian predators, are implicated in the decline or extinction of many animals that were unfamiliar with these terrestrial, olfactory predators (Gibbs 2009;King 2019). Thus, Geodorcus do not have existing natural defences against mammal predators (Emberson 1975;Campbell et al. 1984;Gibbs 2009;Parkes et al. 2015). ...
... Rodents, and other mammalian predators, are implicated in the decline or extinction of many animals that were unfamiliar with these terrestrial, olfactory predators (Gibbs 2009;King 2019). Thus, Geodorcus do not have existing natural defences against mammal predators (Emberson 1975;Campbell et al. 1984;Gibbs 2009;Parkes et al. 2015). One species, Geodorcus ithaginis (Broun, 1893), is thought to be near extinction due primarily to rats (Sherley et al. 1994). ...
Most species co-evolve with their predators and develop strategies to avoid predation. This is not possible when a novel predator invades an environment. Native residents must quickly adapt to their new predator or face local extinction. Intense competition for mating opportunities exerts significant selective pressure that can drive the evolution of exaggerated structures across taxa. However, these elaborate traits can elevate the risk of predation for some organisms. In the present study, we observe the effect that rats have had on a population of endemic New Zealand stag beetles, Geodorcus helmsi. Rats in Rakiura | Stewart Island often prey on stag beetles, taking them to a sheltered area to eat them and discard any uneaten parts of the beetle, namely the head and mandibles. We compared the head size, mandible size and numbers of predated and non-predated male and female beetles in three sites in Rakiura | Stewart Island that differ in their abundance of mammalian predators. We found that the population demography and the size of the beetles differed significantly between sites. Additionally, we determined whether predated beetles were larger than non-predated beetles, across multiple years, regardless of site. We found that overall the predated specimens were larger than the non-predated beetles. The trends found here suggest that exaggeration of the male mandibles increases the predation risk of these iconic beetles, acting as a limit to mandible size.
Implications for insect conservation
Our results show for the first time the effect that novel predators can have on a population of animals with exaggerated sexually selected traits. The presence of novel predators can cause a shift in both population demography and trait distribution.
... rattus exherted a long selection pressure on native species. They also may have pre-adaptive behavioral features, such as the use of hiding refugees to protect from Rattus predation, as noticed among 'tolerant' orthoptera in New Zealand (Gibbs 2009). ...
... ). Conformément au fait que les invertébrés insulaires sont soumis à de tels filtres d'extinction, les arthropodes qui sont particulièrement vulnérables à la prédation du rat présentent un corps de grande taille, sont incapables de voler, et sont souvent terrestres et nocturnes(Towns et al. 2006). C'est le cas de nombreux arthropodes indigènes de Nouvelle-Zélande qui ont évolué en l'absence de mammifères natifs(Gibbs 2009), où l'introduction de R. rattus est datée de 1860 (Atkinson 1973). Les pressions s'exercent également sous les tropiques(Harper and Bunbury 2015), par exemple sur l'atoll de Palmyra, où l'augmentation enregistrée du nombre d'arthropodes après l'éradication des rats noirs atteint 367%. ...
Biological invasions are the first cause of biodiversity loss in island ecosystems. Islands are frequently invaded by invasive alien species which affect native species richness and abundance, disturb ecosystem functioning, modify trophic networks, alter habitat structure, change native animal behavior, etc. A thousand programs to eradicate invasive species were implemented on islands around the world, but the lack of pre- and post-eradication monitoring often makes it impossible to estimate the outcome of such restoration management actions. In this context, a ten-year program of ecological restoration has been developed on Bagaud Island (Port-Cros National Park, France) since 2010, involving the simultaneous eradication of two invasive taxa: Carpobrotus spp. (ice plant) and Rattus rattus
(Black rat). The objective of my thesis was thus to evaluate the consequences of these invasive plant and animal removals on the arthropod assemblage dynamics. Beetle and spider assemblages were sampled using pitfall traps two years before removal (2010-2011), and then every two years after removal, between 2013 and 2019. We observed two different dynamics of the arthropod assemblages according to the invasive taxa removed:
(1) The taxonomic and functional richness of spider and beetle species increased significantly following Carpobrotus removal. Significant changes in assemblage composition were observed between pre- and post-removal years with a high taxonomic turnover rate, while spider and beetle assemblages remained relatively stable in the native shrubland site (that had no Carpobrotus management). Large floricolous beetles (Scarabaeidae) and small non-flying beetles were the most reduced by Carpobrotus removal along with litter-dwelling spiders with trap strategies, such as Oecobius navus. Beetle predators (e.g. Staphylinidae, Carabidae) and detritivores (Tenebrionidae), along with foliage-dwelling spiders which forage on plants like Xysticus, most likely benefited from vegetation opening while the diversification of microhabitats led to the availability of a wider variety of prey. The increase in bare ground cover favored Aelurillus v-insignitus, Nomisia celerima and Zodarion elegans,
which are characterized by an affinity for dry sunny environments. Invasive Carpobrotus
removal thus induced a rapid change (seven years) in beetle and spider assemblage diversity and composition.
(2) After R. rattus control, no differences were observed in beetle and spider taxonomic diversity. Functional indices and spider assemblage compositions varied independently of the rat control, which may have generated indirect cascading effects on beetle composition such as the replacement of predation pressure on arthropods from rats to reptiles and insectivorous birds. Mid-term monitoring, before (two years) and after restoration (seven years), may not be long enough to assess the restoration success of invasive rodent control.
These results suggest that the bottom-up effects of Carpobrotus plants on higher trophic levels are huge, while the top-down effects of Rattus on lower trophic levels are not predominant. Future studies also need to be carried out on other islands and coastal areas of the Mediterranean to test the replicability of our results.
... New Zealand is a large continental island, characterised by the absence of native terrestrial mammals except for two extant bat species (O'Donnell et al. 2013). The evolutionary history of invertebrates inhabiting isolated islands in the absence of mammalian predators has shown that they tend to be larger and flightless (Gibbs 2009). The New Zealand archipelago hosts five endemic arthropod Families (Mystacinobiidae, Mnesarchaeidae, Huttoniidae, Synthetonychidae and Chathamiidae) and more than 20 000 species of invertebrates endemic to the country (Gibbs 2006;Gibbs 2016). ...
... Rats (Rattus spp.), mice (Mus musculus domesticus) and hedgehogs (Erinaceus europaeus) are considered the main threats to invertebrates in native New Zealand forests (Fitzgerald et al. 1996;Alley et al. 2001;Watts et al. 2014). These predators diminish invertebrate populations directly by predation, or indirectly, for example, by habitat modification and competition for food (Gibbs 2009;Simberloff 2010). This extirpation of invertebrates is of concern not only for preventing extinction, but because invertebrates are involved in many ecological processes, being providers (serving as food or hosts for other organisms), eliminators (removing waste products and dead organisms, recycling live plant material and eating other animals) and facilitators (involved in pathogen transmission, pollination, seed dispersal and phoresy) (Erwin & Geraci 2009;Schowalter 2011). ...
In the absence of mammals, the fauna of islands is characterised by high endemism levels and a tendency towards gigantism, flightlessness and longevity. These characteristics have resulted in a high vulnerability to introduced animals, either directly via predation or indirectly through an alteration of food web interactions. Because invertebrates are important components of food webs and essential for many ecosystem processes, we investigated how different mammal and bird communities, present inside and outside a fenced reserve, influenced ground‐dwelling invertebrates on the mainland of New Zealand. Some significant differences in invertebrate community composition were apparent inside versus outside the fenced reserve, predominantly Ctenognathus adamsi (Carabidae) being twenty times more abundant inside the reserve, and rove beetles (Staphylinidae) being eight times more abundant outside the reserve. The introduced blackbird (Turdus merula) was observed more regularly than other predators of invertebrates outside the reserve, while native robins (Petroica longipes) were more highly detected inside the reserve. Despite differences in the vertebrate insectivore community outside the reserve (multiple mammals and introduced birds) compared to inside (mainly native birds), the resulting similarity in net predation pressure may explain the apparent similarity in abundance for most of the other 24 invertebrate taxa examined. Removal of most mammals from within fenced reserves in New Zealand may enable introduced and native birds to flourish, with flow‐on effects on the invertebrate community. We conclude that further study of trophic interactions and additional intervention, may need to be considered if invertebrate conservation is a desired outcome from fenced reserves.
... Many species have been extirpated from large parts oftheir original range, and translocated populations thrive only on islands free from intro duced mammals (Watts and Thornburrow 2009). However, species which shelter in secure, inaccessible refuges have been able to coexist with rats (Gibbs 2009). Similarly, flightless Lepidoptera and their larvae are often preferentially consumed by mice, resulting in local or island-wide extirpation (Angel et al. 2009). ...
... The initial impacts of rats on the invertebrates of previously mammal-free islands are probably most well documented in New Zealand (Gibbs 2009). Based on stomach contents, all three rat species consume earthworms, centipedes, bee tles, weevils, cicadas, spiders, and stick insects, as well as the larvae of these, but terflies, and moths (Atkinson and Atkinson 2000). ...
This chapter investigates the direct impacts of introduced seabird predators on the terrestrial plants and other animals that inhabit seabird islands. It discusses the direct effects of seabird predators on arthropods, mollusks, amphibians, reptiles, land birds, mammals, and plants. It analyzes various studies that look into what determines species' vulnerability to seabird predators. It contains information gathered from systems where the predators are not native. It focuses on five species: cats, foxes, pigs, rats, and mice and looks into their effects on the island's ecology. It also considers the inherent limitations that pose difficulties in assessing the impacts of introduced predators.
... As humans have introduced rats to over 82% of the world's island groups, this effect has been a major driver of global biodiversity loss (Atkinson, 1985). In addition to the well-known impacts on vertebrates, a number of studies indicate that predation by introduced rats and mice can severely affect island invertebrate populations, resulting in local suppression or extinction (Towns et al., 2006;Gibbs, 2009). The majority of these studies come from New Zealand, although a handful from other regions suggest that rodent impacts on island invertebrates may be geographically widespread (e.g. ...
... comm.). Secondly, studies elsewhere suggest that population-level impacts of rats may be most severe for largebodied invertebrates, particularly those with a rodent-free evolutionary history (Gibbs, 2009). Thirdly, the New Zealand case study suggests that the Orthoptera -which includes weta and giant weta (Orthoptera: Anostostomatidae) -are particularly vulnerable to predation by introduced rats (Meads, 1990). ...
Invertebrates dominate many terrestrial ecosystems in terms of biomass, and they also structure ecosystems through their roles as pollinators, detritivores, primary consumers, predators and prey. Invasive rodents (rats and mice) are known to have detrimental effects on many island invertebrates, although these effects are seldom quantified or ecologically understood. Here we provide evidence of the effects of invasive rats (Rattus spp.) on island invertebrate populations using a large-scale natural experiment. We investigated the effects of invasive rats on Falkland camel crickets (Parudenus spp.) in the Falkland Islands (South Atlantic) by comparing an index of camel cricket relative abundance between 18 rat-infested islands, six rat-eradicated islands and 13 naturally rat-free islands (in total, 37 islands). Our study provided two key results. First, camel crickets were up to an order of magnitude more abundant on rat-free islands than on rat-infested or rat-eradicated islands. This difference was larger in native tussac grass Poa flabellata than in other vegetation types. Second, camel cricket populations recovered after rat eradication, because the relative abundance of camel crickets on rat-eradicated islands was intermediate between those of naturally rat-free and rat-infested islands, and among rat-eradicated islands relative abundance was lowest where rats had been cleared most recently. Our results demonstrate severe suppression of a superabundant and large-bodied island endemic invertebrate by invasive rodents, and its prompt recovery after rodent eradication.
... Rising temperatures in alpine areas may allow a wider range of species to enter the alpine zone, increasing predation (Rowe-Rowe et al. 1989;Watts et al. 2011) and competition for resources Macinnis-Ng et al. 2021;Buckley et al. 2022). A significant threat to native fauna in New Zealand is introduced mammalian predators (O'Donnell 1996; Dowding & Murphy 2001;Gibbs 2009). Below the tree line, from coastlines to forested habitats, mice (Mus musculus), rats (Rattus rattus, R. norvegicus, and R. exulans), stoats (Mustela erminea), cats (Felis catus), and possums (Trichosurus vulpecula) have already devastated native flora and fauna that have evolved without mammalian predators (Hare et al. 2019;Vergara et al. 2021). ...
... The flax weevil is one of the few insect species that is fully protected under the Wildlife Act 1953 (Miskelly 2014), and is dependent on flax plants (Phormium spp.) for its survival during all stages of its life cycle; the adult beetles feed on flax leaves, while larvae develop underground, feeding on and within flax rhizomes (Gourlay 1931). Due to predation by introduced mammals, populations of flax weevil persist only on predator-free islands or in alpine areas, which can be remote and difficult to access for research purposes (Gibbs 2009;Towns 2009). ...
... In many island systems, including New Zealand, geographical isolation has rendered many native species vulnerable to predation by recently arrived invasive mammals ( Blumstein, 2002 ;Blumstein and Daniel, 2005 ;Coss, 1999 ;Duncan and Blackburn, 2004 ). The activities of humans and accompanying species over the last 800 years in New Zealand have also led to a dramatic reduction in habitat availability, and population size, for many endemic invertebrates ( Gibbs, 2009 ;St Clair, 2011 ). In these island systems, as well as in other environments with high numbers of endemic species at risk of extinction, fenced ecosanctuaries or aggressive trapping programmes have reduced or eradicated invasive predators for the benefit of native species. ...
Insects have evolved a wide range of behavioural traits to avoid predation, with anti-predator behaviours emerging as important adaptive responses to the specific strategies employed by predators. These responses may become ineffective, however, when a species is introduced to a novel predator type. When individuals cannot recognise an introduced predator for instance, they may respond in ways that mean they fail to avoid, escape, or neutralize a predator encounter. New Zealand's endemic insect fauna evolved in the absence of terrestrial mammalian predators for millions of years, resulting in the evolution of unique fauna like the large, flightless Orthopteran, the wētā. Here we investigate how experience with introduced mammalian predators might influence anti-predator behaviours by comparing behaviours in a group of Wellington tree wētā (Hemideina crassidens) living in an ecosanctuary, Zealandia, protected from non-native mammalian predators, and a group living in adjacent sites without mammalian predator control. We used behavioural phenotyping assays with both groups to examine rates of activity and defensive aggression shortly after capture, and again after a period of acclimation. We found that wētā living in protected areas were more active shortly after capture than wētā in non-protected habitats where mammalian predators were present. Male wētā living in non-protected areas tended to be less aggressive than any other group. These results suggest that lifetime experience with differing predator arrays may influence the expression of antipredator behaviour in tree wētā. Disentangling innate and experiential drivers of these behavioural responses further will have important implications for insect populations in rapidly changing environments.
... Although New Zealand's native wildlife had already been damaged for 600 years by Pacific rats, and for 150 years by Norway rats, the arrival of ship rats in the mid to late nineteenth century posed additional, new threats [105]. All three rat species have been responsible in their turn for the loss of many large, flightless, ground-dwelling endemic invertebrates, such as giant weevils and giant wētā, that are now either extinct or confined to rodent-free islands [106]. In beech forests, foraging by ship rats (and mice) on litterdwelling invertebrates has altered the below-ground community of decomposers [107]. ...
New Zealand had no people or four-footed mammals of any size until it was colonised by Polynesian voyagers and Pacific rats in c. 1280 AD. Between 1769 and 1920 AD, Europeans brought three more species of commensal rats and mice, and three predatory mustelids, plus rabbits, house cats hedgehogs and Australian brushtail possums. All have in turn invaded the whole country and many offshore islands in huge abundance, at least initially. Three species are now reduced to remnant populations, but the other eight remain widely distributed. They comprise an artificial but interacting and fully functional bottom-up predator-prey system, responding at all levels to interspecific competition, habitat quality and periodic resource pulsing.
... This spread of the Pacific rat between the Pacific islands is likely to have been intentional, since the rat seems to have been an important source of protein (Matisoo- Smith & Robins 2004;Commendador et al. 2013). It is believed that the Pacific rat had a huge impact on the native flora and fauna where it was introduced (Steadman 1995;Athens et al. 2002;Gibbs 2009), and has even been accused of contributing to deforestation (Hunt & Lipo 2009). From a human perspective, the impact of the dispersal of the black rat (Rattus rattus) was considerable, with its connection to diseases such as the bubonic plague (Yu et al. 2021). ...
This thesis aims to study the interactions of pre-agricultural societies in Scandinavia with wild mammals, for example in terms of hunting and translocation. More specifically, the aim is to investigate the possibility of identifying examples of overexploitation, targeted hunting or translocation of wild mammals in prehistoric Scandinavia, and to discuss the implications this could have had for both the wild animals and the humans. The thesis also studies translocation to evaluate the feasibility of using it as a proxy for prehistoric human mobility, and to understand the motivation for this action.
Although the focus is on the animals in this thesis, the ultimate purpose is to study humans and their interactions with animals in prehistory. The thesis applies genetic analyses to zooarchaeological material of various mammalian species from different Scandinavian sites, in order to study whether the genetic structures have changed in these species over time, and to assess whether these changes were induced by different human actions. The species studied in this thesis were selected on the basis of the importance they are considered to have had for prehistoric people.
The dissertation comprises five studies. The first study investigates the occurrence of mountain hares on the island of Gotland, and discusses how they got there and where they came from. The second study explores the temporal genetic structure of the grey seal in the Baltic Sea, and discusses whether humans and/or climate were the drivers for the sudden disappearance of grey seals from the island of Stora Karlsö. The third study concerns a shift where moose apparently became less important as prey in northern Sweden at the end of the Neolithic period, and discusses whether humans targeted female moose in hunting. The fourth study analyses and discusses the history of the harp seal in the Baltic Sea. The fifth study is a methodological paper which involves identifying seals according to sex, using the dog genome.
The overall result of the different case studies shows that there were major population fluctuations over time in all the species studied, and that in some cases, humans are likely to have contributed to this, e.g. through overhunting and translocation. The study also shows that the population fluctuations often occurred in connection with certain climatic events, though it was not possible to separate climatic effects from human impact in terms of the cause.
... As the sole exotic rodent for about 500 years until European colonisation in the early nineteenth century (Holdaway 1989), kiore spread quickly across mainland New Zealand (Holdaway 1989;Towns et al. 2006;Gibbs 2009), reaching offshore islands as opportunity arose (Bellingham et al. 2010). However, subsequent introductions of Norway rats (Rattus norvegicus) and ship rats (R. rattus) associated with European colonisation of New Zealand in the late 18th and 19th centuries (Haami 1994;Atkinson and Towns 2005) altered this distribution. ...
Kiore (Pacific rat; Rattus exulans) is both a target for eradication and a taonga or highly valued species in New Zealand, and its abundance and distribution vary considerably throughout the country. We investigated reports of an abundant kiore population on Slipper Island (Whakahau), off the east coast of New Zealand’s North Island, in March 2017. We trapped kiore to examine their distribution across a range of habitats with varying degrees of human activity. Kiore were captured in all habitats, with particularly high abundance at a campground with a fruiting fig tree (50 kiore per 100 trap nights corrected for sprung traps). We found no evidence of other rat species; Slipper Island appears to remain one of few New Zealand islands with kiore but without ship rats (Rattus rattus) and Norway rats (R. norvegicus), the two other rat species present in New Zealand. Slipper Island potentially provides opportunities to research kiore behaviour and population dynamics in a New Zealand commensal environment, and genetics of an isolated island population.
... Additionally, it is still unknown whether NZ rock wrens were present within the North Island prior to European arrival. Polynesian colonization of New Zealand (∼280 A.D.; Wilmshurst et al., 2008) also marked the arrival of kiore, the pacific rat (Rattus exulans), which devastated the invertebrate and small vertebrate faunas of New Zealand (Holdaway, 1989;Towns and Daugherty, 1994;Gibbs, 2009). The current distribution of NZ rock wrens may reflect where populations survived human-mediated extinction pressures. ...
Museum specimens provide a record of past species distribution and are an increasingly important resource for conservation genetic research. The scientific value of these specimens depends upon the veracity of their associated data and can be compromised by inaccurate details; including taxonomic identity, collection locality, and collector. New Zealand contains many endemic species that have been driven to extinction or reduced to relict distributions following the arrival of humans and mammalian predators, including the Acanthisittid wrens (of which only two of the eight described species presently persist). One of these is the New Zealand rock wren (Xenicus gilviventris), currently classified as an endangered species and experiencing ongoing population declines. Here we analyze ancient DNA retrieved from New Zealand rock wren museum skins to establish the veracity of their recorded collection localities—New Zealand rock wrens exhibit strong north-south genetic structuring along the Southern Alps of New Zealand's South Island. We include the only specimen reportedly collected from New Zealand's North Island, outside the known range of New Zealand rock wrens, specimens collected by Henry Hamersley Travers, a collector known for poor record keeping and potentially fraudulent specimen data, and type specimens of proposed Xenicus taxa. Multiple instances of inaccurate collection locality were detected, including that of the New Zealand rock wren reportedly collected from the North Island, which matches individuals from the southern South Island. Syntypes of X. haasti, and a syntype of X. gilviventris clustered with individuals belonging to the northern New Zealand rock wren lineage. Our results suggest that New Zealand rock wrens have not been historically extirpated from New Zealand's North Island, and that caution must be taken when utilizing museum specimens to inform conservation management decisions. Additionally, we describe the type locality of both X. gilviventris and X. haasti, with genetic and historical evidence suggesting that the specimens used to describe these taxa were collected from the headwaters of the Rakaia River. This study demonstrates that ancient DNA analysis can add value to museum specimens by revealing incorrect specimen data and inform the conservation management and taxonomy of endangered species.
... Although the most well-known decline and recovery stories have concerned forest birds, the widespread distributions and diverse body sizes, diets and behaviours of mammal pests in New Zealand have resulted in known or likely impacts on most native biota. These include impacts on seabirds (Buxton et al. 2014), bats (O'Donnell et al. 2010), lizards (Towns et al. 2001), frogs (Longson et al. 2017), terrestrial invertebrates including land snails (Sherley et al. 1998;Gibbs 2009), vegetation (Byrom et al. 2016) and even litter and underground biota (Wardle et al. 2001). There is therefore broad and growing support for pest mammal control to achieve many conservation outcomes beyond birds. ...
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.
... Invasive black rats are considered a pest worldwide (Lowe et al., 2000;King et al., 2011). They are nocturnal omnivores and key predators of invertebrates, lizards, and ground nesting birds (Sultana and Borg, 2006a,b;Towns et al., 2006;Gibbs, 2009). The detrimental effects of such invasive rodents on island ecosystems are well documented (e.g. ...
Invasive species are one of the main causes of biodiversity loss, and rodents in particular are regarded as a real threat worldwide, especially to island ecosystems. The Tuscan Archipelago National Park is the largest in the Mediterranean basin, it harbours a large number of autochthonous endemic species, mostly reptiles and insects, and hosts many migratory birds during their seasonal movements. Although a number of sites in the Archipelago are under strict protection regimes, the invasive black rat Rattus rattus has significantly affected survival of local wildlife. As part of an eradication campaign conducted in 2012 and 2017, we assessed genetic diversity and population differentiation of black rats from a total of six locations on the largest Elba Island, a possible source of invasion, and the southern, small islands of Pianosa and Montecristo using six nuclear DNA microsatellite loci. We recorded a strong population structure and identified the islands of Elba, Pianosa and Montecristo as three distinct eradication units. Despite some degree of admixture was recorded on Elba, the largest island of the archipelago was unlikely the main source of invasive rats to Pianosa and Montecristo. We also recorded evidence of past reduction in population size, particularly in Montecristo, probably due to repeated past founding events. Biodiversity management plans should consider monitoring vessels arriving to the Tuscan Archipelago from the mainland and the major Tyrrhenian islands in order to limit alien invasion. Moreover, as reinvasion can occur a few years after eradication, regular monitoring should be conducted thus to rapidly intercept the arrival of new invaders.
... These three rat species are among the largest contributors to seabird extinction and endangerment worldwide ( Jones et al. 2008). The Pacific rat probably also caused many invertebrate extinctions in New Zealand (Gibbs 2009), and rats are probably a principal cause of the many declines and extinctions among the exceptionally rich ende- mic snail faunas of islands (Hadfield and Saufler 2009). In New Zealand, 25 native species of plants, 15 species of invertebrates, two amphibians, 10 reptiles, 13 birds and two mammals have been affected Its impacts on the avifauna of Guam constitute perhaps the most sobering demonstra- tion of the damage an invasive can do to island biodiversity and the extreme rapidity with which native populations can decline once an introduced species becomes established: most of Guam's native and endemic breeding birds were extinct or nearly so within 35 years of the snake's arrival ( Wiles et al. 2003). ...
... Rats were absent on the East Coast and this did not change either after 1080 treatment or after mast seeding. On the West Coast, rats followed the expected pattern of a significant decrease after 1080 treatment with a rapid recovery the following year (Holdaway 1989;Innes et al. 1995;Gillies & Pierce 1999;Murphy et al. 1999;Alterio 2000;Dowding & Murphy 2001;Speedy 2005;Gibbs 2009). In the North Island, rats increased when possum densities were suppressed, most likely due to competition for food between possums and rats (Ruscoe et al. 2011). ...
We used a long-term replicated before-after control-impact (BACI) sampling design to monitor the effect of aerial 1080 possum-control operations on common forest bird populations. Paired treatment and non-treatment sites in the Rolleston Range (East Coast, South Island) and Alexander Range (West Coast, South Island) were monitored once before 1080 treatment during winter 2012 and for three successive summers afterwards. Mammals (possums Trichosurus vulpecula, rats Rattus spp. and mice Mus musculus) were monitored with chew cards, and forest birds with five-minute counts. Possums decreased to negligible levels in treatment sites, but increased over time in non-treatment sites. Rats were only present at the West Coast sites, where there was a significant, but short-lived, decrease post-1080. Mouse abundance showed almost no effects post-1080, but increased at the East Coast sites after a beech (Nothofagus spp.) mast seeding event. No common native bird species showed short-term negative effects post-1080. Three species-tomtit (Petroica macrocephala), silvereye (Zosterops lateralis), grey warbler (Gerygone igata)-increased significantly. Longer-term effects on birds were nearly all neutral or positive, including bellbirds which increased threefold in treatment areas. In non-treatment areas, higher possum densities were correlated with subsequent decreases in bird counts (averaged across all species). Overall, the one-off aerial 1080 treatment had conservation benefits.
... Polynesian rats are effective predators of seabirds, lizards, insects, and sensitive plant species that did not evolve with mammalian predators. Recent eradication efforts of Polynesian rats on islands have revealed the extent of their negative impacts as species recovery has occurred, including invertebrates and vertebrates (Gibbs 2009;Newton et al. 2016). ...
Approximately 42% of all mammalian species in the world are rodents, amounting to about 2277 species (Wilson and Reeder 2005). Rodents have adapted to all lifestyles: terrestrial, aquatic, arboreal, and fossorial (underground). Most species are small, secretive, nocturnal, adaptable, and have keen senses of touch, taste, and smell. For most species of rodents, the incisors continually grow throughout their life span, requiring constant gnawing to keep the incisors sharp and at an appropriate length. This can result in extensive damage to seeds, fruits, field crops, structures, wires, and insulation. Rodents are known for their high reproductive potential; however, there is much variability between species as to the age at first reproduction, size of litters, and the number of litters per year. All these characteristics make many rodent species ideal invaders. Rodents have ecological, scientific, social, and economic values (Witmer et al. 1995; Dickman 1999). Rodents are important in seed and spore dispersal, pollination, seed predation, energy and nutrient cycling, the modification of plant succession and species composition, and as a food source for many predators. Additionally, some species provide food and fur for human uses. Hence, the indiscriminate removal of native rodents from ecosystems, including agroecosystems, is not the best management option in many cases (Villa-Cornejo et al. 1998; Aplin and Singleton 2003; Brakes and Smith 2005).
... Almost a third (at least 76 of 245) of bird species in pre-human times have become locally or globally extinct, and introduced mammals are the primary factor responsible for these declines (Innes et al., 2010). The kiore (Rattus exulans) arrived with Polynesian settlers and European ships transported three additional rodent species: ship rats (R. rattus), brown rats (R. norvegicus) and the house mice (Mus musculus), which quickly spread throughout the country (Gibbs, 2009). European settlers also introduced two species of lagomorphs as food resources, the European hare (Lepus europaeus) and the rabbit (Oryctolagus cuniculus) (Thomson, 2011). ...
Stoats (Mustela erminea), feral cats (Felis catus) and ferrets (M. furo) were introduced to New Zealand as agents of biological control and have subsequently decimated populations of many native species. Although the detrimental impacts of these predators are unequivocal, the potential limiting factor of competition among these invasive species is less well understood. Predator demographics can be influenced by several factors such as resource-consumer interaction, facilitation and mutualism, as well as the mechanisms that are the focus of this thesis - competition and predation. I investigated the consequences of interference competition and olfactory communication on the distribution and behaviour of the focal species (stoat), in a series of macrocosm and field experiments. Following a general introduction, Chapter 2 describes pen trials that examine changes in stoat foraging behaviour based on the perceived risk posed by larger predators (cats and ferrets). Olfaction, the dominant sense of many mammals, may mediate trophic interactions by allowing subordinate species to assess the risk of encounter. Chapter 3 therefore examines the importance of interspecific olfactory communication and quantifies behavioural changes of foraging stoats when they encountered the odour of apex predators. Chapter 4 tests whether behavioural responses of wild-caught stoats’ are consistent with observations made in the macrocosm, and evaluates the importance of results for conservation. Finally, Chapter 5 investigates whether niche partitioning facilitates invasive predator coexistence and a removal experiment tests the responses of stoats to changes in the densities of larger predators. The thesis concludes with a general discussion and suggestions for future research. Although New Zealand is the main focus, my results may have worldwide conservation applications. Understanding interactions among invasive carnivores, and the communication mechanisms that maintain predator assemblages, is critical for native species protection in invaded ecosystems.
... Polynesian rats are effective predators of seabirds, lizards, insects, and sensitive plant species that did not evolve with mammalian predators. Recent eradication efforts of Polynesian rats on islands have revealed the extent of their negative impacts as species recovery has occurred, including invertebrates and vertebrates (Gibbs 2009;Newton et al. 2016). ...
... It is likely that insect activity induces the production of exudates in Pseudopanax and that adult insects play a role in the spore dispersal of C. schefflerae. A range of weevils such as Pactola variabilis Pascone and Pactola fuscicornis Broun (Mazur et al. 2016), Eiratus parvulus Pascone (Kuschel 1982) and Ectopsis ferrugalis Broun (Gibbs 2009) exclusively colonise species of Pseudopanax and Schefflera digitata. These specialised and presumably ancient insect-plant associations can facilitate the dispersal of the fungal spores, guaranteeing that they reach the specific substrate essential for their germination and growth (Tuovila et al. 2011a). ...
Ascomycetes specialised to live on hardened plant exudates occur worldwide, but the number of species so far described is relatively small (c.30). Particularly within the genus Chaenothecopsis (Ascomycota: Mycocaliciales), many species produce their ascomata on hardened but still relatively fresh outpourings of conifer resin or angiosperm exudate. Temperate rainforests of New Zealand provide habitat for several endemic Chaenothecopsis species, including Chaenothecopsis schefflerae, which was previously known from a single sample collected from the exudate of Schefflera digitata (Araliaceae) in the early 1980s. Here we show that C. schefflerae is neither lost nor very rare, but occurs sporadically throughout New Zealand. The fungus does not primarily grow on Schefflera but on exudate of several species of Pseudopanax (Araliaceae), also endemic to the region. We compare the morphology of the new specimens to the type specimen of C. schefflerae and provide a detailed description of the new material. Phylogenetic analyses based on nuclear ITS and LSU rDNA place C. schefflerae together with other morphologically similar Chaenothecopsis species growing on angiosperm exudates.
... Since the Middle Miocene the New Zealand terrestrial biota evolved free of the influence of nonvolant mammals (Worthy et al. 2006). A product of such an evolutionary setting is a biota naïve to the search and prey handling strategies of ground-dwelling mammalian predators (Gibbs 2009(Gibbs , 2010 introduced with human visitation and settlement commencing with predecessors of the Māori about 750 years ago (Wilmshurst et al. 2008). Among the 34 mammals introduced to date are a suite of predators with important ecological impacts in New Zealand indigenous ecosystems, including dogs, cats, stoats, ferrets, weasels, and four rodents that comprise the house mouse, Pacific rat, ship rat and Norway rat (Atkinson 2001;Blackwell 2005). ...
While invasive rats are demonstrably inimical to indigenous vertebrate species, there has not been unequivocal evidence of benefit to invertebrate communities from management of these invasive mammals in New Zealand forest systems. The present study examined the response of land snail communities to intensive management of ship and Norway rats by sampling paired rainforest blocks, one block of which had been subject to intensive management of rats, while the other block had been without management of invasive rats and thus subject to ambient rodent infestations. Rat tracking index data indicated rat management regimes were generally effective in reducing rat abundance relative to non-treated forest blocks. At the whole community level there was little evidence that forest management regime influenced the structure of land snail communities. However, when only the larger-shelled (≥4 mm maximum shell dimension) component of the communities was considered, strong effects of rat management regime were evident with increased land snail abundances, species richness and functional trait values. These results are discussed in relation to potential direct and indirect of effects of management regimes that reduce rat abundance.
... In the more recent literature, most authors simply acknowledge these comparisons without necessarily supporting such a treatment (e.g. Trewick & Morgan-Richards 2005;Watts et al. 2008a, b;Gibbs 2010), whereas at least one author marginalised the proposition, stating that when Pacific rats (Rattus exulans) invaded New Zealand, the 'rodent niche was empty' (Gibbs 2009). We believe that comparisons between weta and various small mammals might be useful if they lead to a better understanding of niche convergence, or the ecology and potential ecosystem services of weta within the New Zealand forest ecosystem, including diet and seed dispersal studies, as seeds are an important part of rodent diet (Trewick & Morgan-Richards 2004). ...
The distinctiveness of New Zealand's large endemic orthopterans and lack of small mammals in our forest ecosystems led to the description of weta as ecologically equivalent to rodents in other countries. We review the use of this metaphor and the characteristics, such as diet and reproductive behaviour, given to support it. We note, however, that species are rarely specified when comparisons are made, thereby neglecting the ecological diversity of both weta and rodents. We suggest that if these taxa are to be compared, the details of their ecology are important and the scale of their influence in an ecosystem must be taken into account. We consider in particular the relevance of the 'invertebrate mouse' cliché in understanding evolutionary ecology in New Zealand and find it misleading. We show that reproductive potential and scale of change in population size differ greatly between mice and tree weta. We find that endothermic mice (Mus musculus) have a metabolic rate almost 20 times faster than ectothermic tree weta (Hemideina sp.), an intrinsic rate of increase some 275 times higher, and consume a high quality diet dominated by seeds and invertebrates and devoid of leaves, in contrast to tree weta diets. Comparative quantitative analyses of the influence of different animals on ecosystem services, biomass, nutrient cycling and energy turnover of forests in New Zealand and elsewhere will contribute to interpretation of the evolutionary history of the New Zealand biota.
... For many scientists and conservationists, however, the kiore remains a predator endangering indigenous plant, bird, reptile and invertebrate species (Campbell & Atkinson 1999;Towns & Broome 2003;Gibbs 2009). An agreement between Ngātiwai and the Department of Conservation to protect and monitor a population of kiore on the Marotere Islands (Northland) while eradicating them from a larger nearby island, Taranga or Hen, is perhaps a good example of how differing values can be accommodated (Parrish 2008). ...
Recognition and management of anthropogenic environmental impacts as ‘biosecurity’ is a relatively new concept to our society. Although biosecurity risks are based on biological impacts, biosecurity management is truly interdisciplinary-transdisciplinary since the definition and interpretation of risk and adverse effects are socially constructed, and the outcomes and management of the risks can have significant social and economic impacts. The New Zealand biosecurity strategy is very clear that the responsibilities for environmental risk management lie with society as a whole. The authors explore how disciplines other than biology may contribute to the understanding of biosecurity risks, their management and mitigation. This paper outlines the interdisciplinary-transdisciplinary nature of biosecurity, with an emphasis on the social and economic elements.
... In New Zealand, the ship rat is one of a suite of four invasive rodent species; the others being the Norway rat (R. norvegicus), the kiore or Pacific rat (R. exulans) and the house mouse (Mus musculus). As a result of a long history of evolutionary isolation and a lack of native terrestrial mammals (other than bats), the indigenous flora and fauna of New Zealand are particularly vulnerable to mammalian predation (Gibbs 2009). Ship rats are a pervasive and persistent problem throughout New Zealand and are one of the species most commonly targeted for control or eradication operations. ...
... Nevertheless, detailed knowledge of their ecology in the wild is limited, even to the extent that information of their diet is fragmentary. One general observation is that tree weta (Hemideina spp.) are, unusually for their family, predominantly herbivores (Meads 1990;Green 2005;Trewick & Morgan-Richards 2005;Gibbs 2009;Wehi & Hicks 2010; but see Barrett 1991). More precisely, Hemideina appear to thrive on a diet of leaves. ...
Tree weta are well known insects of New Zealand's forest ecosystems; however, there is limited research into their general ecology. A literature review suggests they are mainly herbivores. Wellington tree weta, Hemideina crassidens, were given the choice of possible foods that they may come into contact with in the wild. Unexpectedly, leaves of Coprosma robusta were consumed the least by the weta, which suggests a more accurate label for the diet of H. crassidens may be omnivory. There are possible implications for the mixing of foods in the diet that need further investigating.
... To accurately reconstruct the geographical sister group relationships within species, dense sampling is needed across the range of those species. Microarthropods, such as leaf litter and dead wood Coleoptera, are particularly appropriate because they are more resilient to human-induced environmental change than macro-arthropods (Kuschel & Worthy, 1996;Gibbs, 1998Gibbs, , 2009Leschen & Rhode, 2002). For these reasons, we have sampled mitochondrial (mt)DNA cytochrome oxidase c subunit I (COI) sequences from multiple individuals from Three Kings populations and a large number of mainland populations for six insect groups aiming to determine: ...
We have used comparative phylogenetic analysis to infer the age and biogeographical origins of the Three Kings Islands insect fauna, an archipelago only 56 km off the northern tip of New Zealand. We densely sampled six insect lineages (five Coleoptera, Brachynopus latus, Brachynopus scutellaris, Tarphiomimus spp., Epistranus lawsoni, and Syrphetodes spp., and one Phasmatodea, Pseudoclitarchus sentus) throughout New Zealand and sequenced mitochondrial DNA to assess phylogenetic relationships and determine ages of haplotype lineages on the Three Kings Islands. We recovered two biogeographical patterns. The first pattern was seen in three taxa, B. latus, Syrphetodes spp., and E. lawsoni, which had sister group relationships between the Three Kings and the adjacent North Cape region at the very northern tip of New Zealand. The second pattern, inferred in P. sentus, B. scutellaris, and Tarphiomimus spp., was where Three Kings lineages had sister groups that were widespread throughout most or all of New Zealand. The divergence dates, estimated using a range of previously estimated substitution rates, ranged from as old as 24 Mya in B. scutellaris to as young as 2.24 Mya in Tarphiomimus. These results are consistent with continual emergent land on the Three Kings Ridge since at least the Miocene and a lack of land connections between the Three Kings Islands and mainland New Zealand during Pleistocene sea‐level lowering. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108, 361–377.
... We recommend investigation of other sites with burrowing petrels, to see if a similar biogeochemical bottleneck is present. Ideally, such investigations would include sites less affected by introduced predators, given that mice and rats adversely affect both abundance and faunal composition of terrestrial invertebrates (Marris 2000;Gibbs 2009). Investigation of summer breeding petrels would be particularly interesting, as increased summertime invertebrate abundance would coincide with the pulse of detritus from the seabirds. ...
Seabirds deposit large quantities of marine detritus on land, but little is known of the soil arthropods processing this material. Burrow-nesting seabirds concentrate their activities within their burrows, so we tested the hypothesis that burrow arthropod fauna is more marine-like in its isotopic enrichment (C/C, N/N; expressed as δC and δN) than the arthropods on the adjacent forest floor. Results from a Westland petrel (Procellaria westlandica) colony on the South Island of New Zealand did not support the hypothesis. Instead, δN was universally marine (13–22‰). While δC separated into two clusters, the distribution was not according to arthropod provenance. Most taxa had a terrestrial δC; only two taxa (a leiodid beetle and the mesostigmatic mite Ayersacarus woodi) incorporated marine C. The leiodid beetle occurs both in burrows and on the forest floor; beetles from both habitats had a marine δC. Ayersacarus woodi is found only in burrows. We conclude that, in this system, marine and terrestrial detrital C is processed separately, and that marine detrital C enters the terrestrial ecosystem through a very few arthropod taxa.
... The human colonization of isolated archipelagos usually results in a wave of extinctions in the native biota (James 1995, Blackburn & Gaston 2005. The widespread invasive rodents (Rattus spp.) that accompany humans have been implicated in the decline and extinctions of many island endemic vertebrates and invertebrates (Towns et al. 2006, Gibbs 2009). Many larger-bodied insects are now rare or threatened following the introduction of rodents to New Zealand (St Clair 2011). ...
Wetapunga (Deinacrida heteracantha), New Zealand's largest insect, were formerly abundant in forests of northern New Zealand. However, they are now restricted to onepopulation on mammal-free Little Barrier Island (3083 ha). This study investigated the movements, habitat use and behavior of 22 adult wetapunga fitted with miniature radiotransmitters for up to 18 nights. Adult wetapunga appeared to be quite mobile, with males (16 m per night) moving further than females (8 m per night). Differences in the distances travelled by adult male and female wetapunga between daytime refuges appear due to differences in reproductive behavior. Wetapunga were associated with silverfern, nikau palm, kanuka, and kohekohe within second-growth coastal forest on Little Barrier Island. The majority of wetapunga were found above ground level, but were also occasionally found moving on the ground. In addition, adult wetapunga were found in relatively open sites with little or no cover and were clearly visible by day. Wetapunga were generally solitary and the majority of their activities, such as feeding, movements and oviposition, occurred at night. The one exception is mating (actual copulation and pre-, post-copulatory behavior), which usually occurred during daylight after weta had paired during the previous night. During the study, one male wetapunga was eaten by an unknown avian predator. Radiotelemetry has extended our knowledge of adult wetapunga behavior and this monitoring technique could be readily applied to other large invertebrates.
... It is likely that rats have a substantial effect on abundances of their principal prey items in mainland forests, perhaps in part due to naivety of prey to non-native predators. Indeed many of New Zealand's endemic invertebrates have been extirpated from the mainland and survive only on rat-free offshore islands (Ramsay 1978;Gibbs 2009). Nevertheless, it is unclear which taxa are most strongly affected by rats and whether current levels of control on the mainland are sufficient to allow recovery of affected species. ...
Predation on native fauna by non‐native invasive mammals is widely documented, but effects of predation at the population level are rarely measured. Eradication of invasive mammals from islands has led to recovery of native biota, but the benefits of controlling invasive mammal populations in settings where eradication is not feasible are less understood. We used various combinations of aerially delivered toxic bait and control measures on the ground to reduce abundances of invasive rats (Rattus rattus) to low levels over large areas on mainland New Zealand and then monitored the abundance of invertebrates on replicated treatment sites to compare with abundances on similar nontreatment sites. We also assessed rat diet by examining stomach contents. Abundance of the rats’ most‐consumed invertebrate prey item, the large‐bodied Auckland tree weta (Hemideina thoracica), increased 3‐fold on treatment sites where we maintained rats at <4/ha for approximately 3 years, compared with the nontreatment sites. Auckland tree weta also increased in abundance on sites where rats were controlled with a single aerial‐poisoning operation, but rat abundance subsequently increased on these sites and tree weta abundance then declined. Nevertheless, our data suggest that biennial reduction of rat abundances may be sufficient to allow increases in tree weta populations. Other invertebrates that were consumed less often (cave weta [Rhaphidophoridae], spiders [Araneae], and cockroaches [Blattodea]) showed no systematic changes in abundance following rat control. Our results suggest that the significant threat to recruitment and individual survival that predation by rats poses for tree weta can be mitigated by wide‐scale aerial pest control .
Efectos del Control Extensivo Espacial de Ratas Invasoras sobre la Abundancia de Invertebrados Nativos en Bosques de Nueva Zelanda
Recent years have seen a shift in the social scientific study of introduced species. Social scientists have shown that popular interpretations vary beyond the critical, invasive frameworks and include more celebratory or welcoming responses. Yet this research has taken the form of case studies. This has limited comparative inquiry. In response, this article develops a typology of sociocultural responses to introduced species by nonspecialists. The article then discusses major forms of collective meaning-making that go into creating these different cultural types.
The negative ecological impacts of invasive species are well documented, although their effects are often more pronounced on islands than on the mainland. This is because many island species exhibit high degrees of endemism, have small geographic distributions, are rare, and exhibit low genetic diversity, which reduces their ability to respond to new emerging threats. One of the world’s most notorious invasive species is the cane toad (Rhinella marina), which is a voracious predator that is native to the neo-tropics but was intentionally introduced in the early 20th century to many warm regions and islands to control crop pests. Cane toads produce two kinds of toxins in neck glands that are often lethal to non-adapted predators in the invasive range. Although well-studied in Australia, their ecological impacts on many islands have received much less attention. Australia is the sixth largest country on Earth, so the effects of cane toads on small island nations may differ considerably from there. Here, we discuss the potential ecological impacts of cane toads in the Philippines and on other island nations. Cane toads were introduced onto the largest Philippine island, Luzon, in 1930 and have since spread over all but a few of the 7641 islands that make up the country. We speculate that, unlike most biological invasions with predators or herbivores where the ecological effects are strictly ‘top-down’, cane toads, by virtue of their biology and ecology, may have even more serious effects on island fauna because they exhibit both ‘top-down’ and ‘bottom-up’ effects.
Predation by introduced mammals frequently limits abundance of New Zealand’s native invertebrates. We investigated responses of beetle and wētā communities to mammal eradication at two fenced forest sites at Maungatautari. Ground-dwelling beetle abundance, but not species richness, increased inside the southern exclosure two years after all mammals were eradicated. In the next 5 years, when all mammals except mice were eradicated from all of Maungatautari, beetle abundance and species richness were frequently higher in the mouse-free southern exclosure. Beetle community composition changed after mammal eradication, and over time with increasing mice densities outside the southern exclosure. Large, predatory, and native beetles showed the most differences between inside and outside the southern exclosure over some years. Wētā were more responsive to mammal removal than beetles. Wētā abundances both inside and outside the southern exclosure were similar when most mammals were eradicated and mice were controlled to low numbers. However, wētā declined in the following 2 years outside the southern exclosure when mouse abundance increased. Abiotic and biotic factors affecting the beetle and wētā communities are complex and interactions poorly understood. This study indicates that climate and predation by native fauna are likely to be important factors.
Nonnative rodents pose a grave threat to many species on islands where they have been introduced. We surveyed accumulated food contents of husking stations, sheltered areas that rats use to process their collected food items, to gain insight into diets of invasive rodents and their potential effects on plant communities on the Hawaiian island of O'ahu. We examined 59 husking stations in four forests across the island in the summer of 2015. Camera traps documented only black rats (Rattus rattus) using the stations. A combination of vegetation surveys and seed rain traps was used to compare abundance of plant species in husking stations with their abundance in the forest. Overall, we identified 13,007 potential food items, including seeds or husks from 15 plant species, plus the remains of snails, arthropods, and other invertebrates. The only native plant species was the tree Nestegis sandwicensis (Oleaceae). We found almost no evidence of successful germination, indicating that rodents, at least in the context of items brought to husking stations, are acting primarily as seed predators in this system.
Cambridge Core - Natural Resource Management, Agriculture, Horticulture and forestry - Species Conservation - edited by Jamieson A. Copsey
Biological invasions are one of the great threats to Earth’s ecosystems and biodiversity in the Anthropocene. However, species introductions and invasions extend deep into the human past, with the translocation of both wild and domestic species around the world. Here, we review the human translocation of wild plants and animals to the world’s islands. We focus on establishing criteria used to differentiate natural from human-assisted dispersals and the differences between non-native and invasive species. Our study demonstrates that, along with a suite of domesticates, ancient people transported numerous wild plants and animals to islands and helped shape ecosystems in ways that have important ramifications for modern conservation, restoration, and management.
For effective and efficient pest management it is essential to understand the ecology of the target species and recipient ecosystems. The use of rodent eradication as a restoration tool is well established in temperate regions, but less common in the tropics, presenting an opportunity to undertake scientific learning in tandem with rodent eradications. On a dry tropical archipelago, we used a Before-After-Control-Impact framework to document (1) fluctuations in the abundance and demography of invasive Rattus rattus and Mus musculus on three different islands, (2) the trophic niche of all three invasive rodent populations, and (3) changes in the invertebrate community before and after rodent eradication, also comparing with two rodent free islands. While rat density was high and relatively stable throughout the year, the two mouse populations greatly differed in body size and seasonal dynamics, despite their proximity. The rodents in all three populations were generalist and opportunistic feeders, although stable isotope analyses results indicated major differences among them, driven by food availability and rodent species. Seasonal fluctuations in invertebrate communities depended on rodent invasion status, but recovery in the invertebrate communities one year after rodent removal was limited for all islands. Predictions for other tropical ecosystem biomes require long-term research on more tropical islands. Improving our understanding of island and species-specific contexts of rodent eradications can advance island restoration projects and assist the selection of indicator species for ecosystem recovery.
Australia and New Zealand are home to a remarkable and unique assemblage of flora and fauna. Sadly though, by virtue of their long isolation, and a naïve and vulnerable biota, both countries have suffered substantial losses to biodiversity since European contact. Bringing together the contributions of leading conservation biologists, Austral Ark presents the special features and historical context of Austral biota, and explains what is being conserved and why. The threatening processes occurring worldwide are discussed, along with the unique conservation problems faced at regional level. At the same time, the book highlights many examples of conservation success resulting from the innovative solutions that have been developed to safeguard native species and habitats in both New Zealand and Australia. Austral Ark fills an important gap regarding wildlife gains and declines, and how best to take conservation forward to keep this extraordinary area of the world thriving.
Pre-human New Zealand had some unusual feeding guilds of birds (e.g. the herbivorous moa fauna), thought to have developed as a result of the absence of a 'normal' mammal fauna. Insectivorous birds, on the other hand, are an integral part of all the world's ecosystems, regardless of the presence or absence of mammals. While it is acknowledged the overall predation impact from birds in New Zealand is unlikely to have differed greatly from elsewhere, the low impact of mammalian insectivores (apart from microbats), coupled with the presence of a specialised avian feeding guild that concentrated on ground-active prey, might have exerted certain unique selection pressures. Do New Zealand invertebrates reflect this? It would be necessary to compare the New Zealand invertebrate fauna with that of mammal-dominated lands in greater detail than is available today before we could assert whether any unique anti-predator characteristics have evolved. Knowledge of the insects that succumbed to extinction when mammals invaded New Zealand should provide clues to avian-adapted features that might have rendered them particularly vulnerable to introduced rodents. Predation by kiwi (Apteryx spp.), an extraordinarily mammal-like nocturnal bird, may to some extent have prepared the invertebrate fauna for the arrival of small mammals.
Many invasive rodent species have become established in the United States and its territories, both on the mainland and on islands. While most were introduced accidently, some were introduced for food or fur. These rodents have caused serious impacts to native flora and fauna, agriculture, and other resources. They have caused the extinction of many species of birds in insular ecosystems. Although many methods are used to control or eradicate introduced rodents, rodenticides and traps are the main tools. Since the early 1990s, agencies have been eradicating rodents from various islands, primarily for conservation purposes. There have been numerous eradication attempts in the United States and most have been successful. We review introduced rodent impacts and eradications, both successful and unsuccessful, which have occurred, with an emphasis on the United States. Finally, we consider some research needs and some remaining challenges in invasive rodent management and eradication in the United States, including the use of toxicants, land access, public attitudes, resource availability, and monitoring difficulties.
Introduced pest mammals impact widely on New Zealand invertebrates, but community-level responses to mammal removal are largely unmeasured. Beetles were pitfall-trapped for 7–10 years to examine how their communities responded to near eradication of all mammals except mice (Mus musculus) within a fenced sanctuary (Zealandia), and to sustained mammal control at an unfenced sanctuary (Otari-Wilton's Bush). In Zealandia, beetle abundance unexpectedly declined for 6 years after mammal eradication before stabilising. Beetle community composition changed, perhaps due to increased predation by birds and mice, but species richness, size distribution and trophic composition did not. At Otari-Wilton's Bush, beetle abundance also declined, in the presence of few but diverse mammals. Identifying causes of invertebrate community changes will be improved with study replication, more ‘before’ data, and targeted measurement of possible explanatory factors. Five recommendations are made for future insect community monitoring, including reconstructing fossil invertebrate communities to sharpen restoration objectives.
Giant weta (Orthoptera: Anostostomatidae) are large flightless New Zealand insects vulnerable to predation from introduced mammals. Some species have been transferred to islands or mammal-free mainland sanctuaries to establish additional populations. Radiotelemetry was used to investigate behaviour, movements and survival of adult Cook Strait giant weta (Deinacrida rugosa) immediately after translocation into Karori Sanctuary, New Zealand, to describe their initial movements, and to assess the importance of this establishment phase in relation to the long-term viability of the population. The average distance moved between consecutive daytime refuges for translocated male D. rugosa within Karori Sanctuary was significantly further than for resident weta on Matiu-Somes Island. In contrast, translocated female weta moved significantly smaller distances between consecutive daytime refuges within Karori Sanctuary than those on Matiu-Somes Island. Translocated D. rugosa travelled significantly further between consecutive daytime refuges between 19 and 45 days after release than during the first 19 days and more than 45 days of radiotracking. Deinacrida rugosa survived well following translocation and there was only limited evidence of predation despite an increased abundance of indigenous avian and reptilian predators being present, and the presence of low numbers of mice. The establishment potential of this population was not adversely affected by movements and survival of the weta immediately after translocation. It still remains to be seen if a self-sustaining population of D. rugosa develops in Karori Sanctuary but the indications are that the species is present because progeny of the translocated weta are regularly seen within Karori Sanctuary. Radiotelemetry provided valuable insights into the behaviour of adult D. rugosa and it could be appropriate for monitoring other large bodied invertebrates.
We examined fossil evidence for persistence of species in New Zealand Quaternary beetles from three Early–Mid-Quaternary sites (aged 1.3 Ma, 1 Ma and 0.53 Ma) in the Auckland area, northern New Zealand. The fossil sites are forest and wetland deposits preserved beneath volcanic deposits ranging from Early–Mid-Pleistocene. Extreme vegetation changes during the Quaternary did not occur in warm temperate-marine northern New Zealand, and Quaternary environments were relatively stable. We recorded 29 fossil beetle taxa from this area and compared these with all other New Zealand sites. While there was evidence for species persistence, there were three potential extinctions in southern localities where Quaternary climates were more extreme.
New Zealand has three main islands and many smaller ones at mid-temperate latitudes, steep topography and many rivers, mostly
flowing east or west, with hard rock gravels, and many lakes, all of them young and most of them either volcanic (North Island)
or glacial (South Island). Early biogeographers were Charles Darwin and Alfred Wallace, with strong interest from local biogeographers
from the late nineteenth century, particularly palaeontologist Charles Fleming. The New Zealand freshwater fish fauna has
derivations from diadromous species that can disperse across oceans and around the coastline. The advent of plate tectonics
profoundly influenced biogeography through the last half of the twentieth century, but it is uncertain whether this has had
any implications for the derivation of the freshwater fish fauna, a topic that has been highly controversial.
The secretion of defensive chemicals onto the skin is a widely used mechanism for predator defence in anurans. Secretions often consist of a mixture of bioactive peptides with cytotoxic or neurotoxic effects. In New Zealand, introduced rodents have been suggested as main drivers for declines and extinctions of endemic frogs. We demonstrate the efficacy of Leiopelma pakeka secretions in deterring rats (Rattus norvegicus Long-Evans) from ingesting secretion-covered food and showed that they can successfully lyse rat erythrocytes. When offered a choice, rats displayed a significant preference for food pellets coated with water over those covered in frog secretions. Direct oral exposure to the secretions has no significant effects on water or food intake of rats. Video analysis showed no significant difference in the proportion of time rats spent grooming, rising on hind legs, motionless or investigating associated with exposure to the secretions. This study provides new insight into the defensive function of leiopelmatid skin secretions.
Eradications of kiore or Pacific rats (Rattus exulans) from islands around New Zealand have been followed by responses from resident species of coastal plants, invertebrates,
reptiles and seabirds. These responses are compared with an invasion by ship rats (Rattus rattus), which devastated populations of invertebrates, birds and bats. Post-eradication responses only approximate the effects
of invasions because recovery is limited to the residual pool of native species. Greater effects of kiore are indicated by
adding incompatible species confined to rat-free locations. The extended list includes at least 15 species of invertebrates,
two species of frogs, tuatara (Sphenodon punctatus), 11 species of lizards and 9 species of seabirds. The analyses indicate direct and indirect effects of kiore similar to
those reported after ship rat invasions. This is despite indications from the literature that kiore are the least damaging
of the three commensal rat species.
Archaeophylax worthyi n. gen, n. sp., is described from a nearly complete late Holocene fossil collected in layer 4 of Flc Cave in the Waitomo region of the North Island of New Zealand. The length of A. worthyi is estimated to be 24.5 mm and it is the largest member of Ulodidae. The fusion of the elytra suggests that A. worthyi was flightless, and it is presumed that extinction of the species was due to its large size and vulnerability to introduced predators.
Over the last four decades the eradication of rats from islands around New Zealand has moved from accidental eradication following the exploratory use of baits for rat control to carefully planned complex eradications of rats and cats (Felis catus) on large islands. Introduced rodents have now been eradicated from more than 90 islands. Of these successful campaigns, those on Breaksea Island, the Mercury Islands, Kapiti Island, and Tuhua Island are used here as case studies because they represent milestones for techniques used or results achieved. Successful methods used on islands range from bait stations and silos serviced on foot to aerial spread by helicopters using satellite navigation systems. The development of these methods has benefited from adaptive management. By applying lessons learned from previous operations the size, complexity, and cost effectiveness of the campaigns has gradually increased. The islands now permanently cleared of introduced rodents are being used for restoration of island‐seabird systems and recovery of threatened species such as large flightless invertebrates, lizards, tuatara, forest birds, and some species of plants. The most ambitious campaigns have been on remote subantarctic Campbell Island (11 300 ha) and warm temperate Raoul Island (2938 ha), aimed to provide long‐term benefits for endemic plant and animal species including land and seabirds. Other islands that could benefit from rat removal are close inshore and within the natural dispersal range of rats and stoats (Mustela erminea). Priorities for future development therefore include more effective methods for detecting rodent invasions, especially ship rats (Rattus rattus) and mice (Mus musculus), broader community involvement in invasion prevention, and improved understanding of reinvasion risk management.
The behaviour of arthropods on islands with and without mammalian prcdators in South West Fiordland was compared. The escape responses of cockroaches, tree wetas and spiders on islands with prcdators were significantly more pronounced than on predator-free islands. The implications of this result for arthropod population estimatcs and conservation are discussed.
A survey of 12 fossil sites in North and South Canterbury, where faunal remains were accumulated by the apparently extinct laughing owl (Sceloglaux albifacies Gray) and the New Zealand falcon (Falco novaeseelandiae Gmelin), revealed sediments containing abundant remains of not only bones but also invertebrates. Amongst the latter were several species of large weevils (Curculionidae), including Anagotus stephenensis Kuschel, A. rugosus (Broun), Hadramphus tuberculatus (Pascoe), and Ectopsis ferrugalis Broun. Their current and past distributions are discussed. H. tuberculatus has not been found for 84 years, hence is presumed extinct. The others had their territories greatly reduced, in particular A. stephenensis which now is known only from Stephens I. which it shares with the tuatara (Sphenodon punctaius Gray), a likely natural predator. The clearing of vast areas of native vegetation for pastures and crops might have played a part in the likely extinction of H. tuberculatus because its host plant Aciphylla (Apiaceae) is a prickly pastoral weed. However, the main cause of the drastic reduction in territory and numbers of the large weevils came from rats and mice. Some samples of devastation caused by rodents are presented. In New Zealand, large weevils are now more numerous and diverse on the mountains titan in the lowlands in New Zealand, which could well be attributed to some extent to the introduced predators.
Understanding the factors that drive the dynamics of remnant populations of long-lived species presents a unique challenge for conservation management. The long-lived Brothers Island tuatara Sphenodon guntheri is represented by one natural, self-sustaining population on 4-ha North Brother Island, New Zealand, and two small, translocated populations. The North Brother Island population was almost driven to extinction by extreme habitat modification and collecting in the late 19th century. Analysis of a long-term (1957–2001) dataset, following the population's recovery, reveals a significant decline in tuatara body condition over time, which is more pronounced in females. Declining body condition, coupled with very low reproductive output, may be symptomatic of a density-dependent response to elevated population size exacerbated by resource limitation. Sex-specific effects that disadvantage females could compromise this small population, particularly as it exhibits a male-biased sex ratio. We recommend removal of infrequently used structures and habitat restoration to alleviate intense resource competition. Population-level manipulation should be considered if future monitoring indicates an increasingly male-biased sex ratio and continued decline of female body condition.
In vision, there is a trade-off between sensitivity and resolution, and any eye which maximises information gain at low light levels needs to be large. This imposes exacting constraints upon vision in nocturnal flying birds. Eyes are essentially heavy, fluid-filled chambers, and in flying birds their increased size is countered by selection for both reduced body mass and the distribution of mass towards the body core. Freed from these mass constraints, it would be predicted that in flightless birds nocturnality should favour the evolution of large eyes and reliance upon visual cues for the guidance of activity.
We show that in Kiwi (Apterygidae), flightlessness and nocturnality have, in fact, resulted in the opposite outcome. Kiwi show minimal reliance upon vision indicated by eye structure, visual field topography, and brain structures, and increased reliance upon tactile and olfactory information.
This lack of reliance upon vision and increased reliance upon tactile and olfactory information in Kiwi is markedly similar to the situation in nocturnal mammals that exploit the forest floor. That Kiwi and mammals evolved to exploit these habitats quite independently provides evidence for convergent evolution in their sensory capacities that are tuned to a common set of perceptual challenges found in forest floor habitats at night and which cannot be met by the vertebrate visual system. We propose that the Kiwi visual system has undergone adaptive regressive evolution driven by the trade-off between the relatively low rate of gain of visual information that is possible at low light levels, and the metabolic costs of extracting that information.
Wetas are native to New Zealand and in evolutionary terms are insect 'dinosaurs' within the Orthoptera. Related species occur in South Africa, Australia, North America and to a lesser extent, Europe. This book brings together all known information on these groups (mostly in superfamilies Stenopelmatoidea and Gryllacridoidea) to form a compendium of existing scientific knowledge for future biological investigation and conservation. It is particularly useful for those working and researching in the areas of entomology, ecology and evolution, and contains 26 chapters by various authors in sections on: Systematics and biogeography (7 chapters); Morphology and anatomy (4 chapters); Ecology (3 chapters); Behaviour (5 chapters); Reproduction and development (2 chapters); Physiology (4 chapters); and Conservation of endangered species (1 chapter). A review of the Gryllacrididae is included, because of confusion over common names. A list of contributors and an index are also provided.
Wetas are native to New Zealand and in evolutionary terms are insect 'dinosaurs' within the Orthoptera. Related species occur in South Africa, Australia, North America and to a lesser extent, Europe. This book brings together all known information on these groups (mostly in superfamilies Stenopelmatoidea and Gryllacridoidea) to form a compendium of existing scientific knowledge for future biological investigation and conservation. It is particularly useful for those working and researching in the areas of entomology, ecology and evolution, and contains 26 chapters by various authors in sections on: Systematics and biogeography (7 chapters); Morphology and anatomy (4 chapters); Ecology (3 chapters); Behaviour (5 chapters); Reproduction and development (2 chapters); Physiology (4 chapters); and Conservation of endangered species (1 chapter). A review of the Gryllacrididae is included, because of confusion over common names. A list of contributors and an index are also provided.
The rare Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), a large flightless insect originally confined to 13 ha Middle Island in the Mercury Islands, New Zealand, was last seen there in January 2001. Half-grown or larger insects from a captive-breeding programme were released onto nearby Red Mercury Island (34 ♀, 16 ♂) and Double Island (65 ♀, 19 ♂) in 2000 and 2001 to reduce the potential for accidental extinction. Most (108) were released under individual artificial cover objects (ACOs)-clear Perspex discs under plastic plant-pot saucers- and 26 were placed in artificial holes in soil. Usually <10% were found again under ACOs for up to 18 months including 7.5 months as adults. Adults, found in 2005 and 2006, were 1st to 3rd generation island-bred weta (lifespan 1.7-3.2 years). Ongoing monitoring is planned to confirm long-term success. Inbreeding depression is likely so supplementation from Middle Island is required but they may be extinct there. Scraping the soil to expose weta in underground galleries was the best monitoring method. Few were found by searching with lights at night but adults could be located by following other adults equipped with harmonic radar transponders or micro-transmitters.
Although fossil beetle research in New Zealand (NZ) is in the early stages, the beetle fossil record now extends to the early-mid-Pleistocene and shows there has been stasis in NZ Quaternary beetles. In northern NZ locations where forest remained in place during glaciations, beetle communities appear to have remained unchanged over the Quaternary. In contrast, fossil beetle communities from mid- and southern NZ are distinctly different from the modern communities in these locations.A new temperature prediction model is developed that is suitable for NZ conditions. It uses maximum likelihood estimates attached to a sine function to predict the temperature distributions of taxa.Beetles provide precise local paleoecological information that includes the identification of forest at glacial sites that had previously been considered nonforested. The fossil data provide the first evidence that modern biogeographical patterns, such ecological gaps, are a result of the last glaciation.
At 270,000 km2, New Zealand is one-thirtieth the area of Australia, one-third that of Madagascar, twice that of Cuba, and comparable in area to the British Isles, to the Philippines, and within the United States to the State of Colorado. Isolated in the southwestern Pacific, 1900 km east of Australia, New Zealand was the last major habitable landmass to be peopled, in this instance by Polynesians. Unlike the British Isles and the Philippines, which are partly on and partly off the continental shelf, New Zealand is so remote that despite zoogeographic and geotectonic evidence of a considerable antiquity, it lacked nonvolant land mammals when humans and their commensals colonized 700 years ago.
The density of indigenous invertebrates was sampled on three islands in Fiordland which have similar soils, vegetation and climate, and presumably also originally had similar invertebrate faunas. Resolution Island (20,860 ha) now supports stoats and deer, and Breaksea Island (150 ha) has Norway rats; Gilbert Island No.6 (20 ha) is still completely free of mammals. Compared with Gilbert No. 6, the densities of 13 groups of invertebrates were lower on Breaksea, and the densities of 2 groups were lower on Resolution. We interpret these differences to be the result of disturbance and predation by mammals introduced within the last 200 years.
Kiore carry food to husking stations to feed, where they are sheltered from predators, competitors and rain. On 4 northern offshore islands of New Zealand remains of plant foods left in husking stations and in the open included seeds, leaf laminae, shoots, bark, flowers and root bases. A wide variety of animal remains were identified in husking station material, from habitats as diverse as tree tops and below the ground. All stages of both small social and large solitary insects were eaten.-from Authors
The vaginal and intersegmental pouches observed in female Curculionoidea are reported and termed according to location. Subfamily characters are reassessed and 18 taxa previously with subfamily rank are demoted to tribes of Molytinae. These are listed with the other tribes of the world fauna of the subfamily. A few general remarks on the New Zealand molytine elements are made and a key to the genera of the tribe Molytini of New Zealand is presented. Four species are described from New Zealand: tribe Molytini — Karocolens pittospori n. g., n. sp., Lyperobius coxalis n.sp., and L. nesidiotes n.sp.; tribe Phrynixini — Tymbopiptus valeas n.g., n.sp. (based on 1800 and 1680 years old subfossil fragments of a presumably extinct fern-weevil). The genus Germainius n.g. is erected for the Chilean fern-weevil Philippius laesicollis (Fairmaire & Germain). The following synonymies of genera are established: Euodontus Broun, 1883 (also spelt Eudontus) is synonymised under Pogonorhinus Broun, 1883; Metopotoma Casey, Nov. 1892 under Dioptrophorus Faust, Aug. 1892; Stewpeckia Osella, 1980 under Lymantes Schoenherr, 1838; and Neophycocoetes O'Brien & Wibmer, 1982 under Thalasselephas Egorov & Korotyaev, 1976.
Abstract A population of Hemideina crassidens (the Wellington tree weta) was monitored over a 4-year period after the eradication of Rattus exulans (the Polynesian rat kiore) and Gallirallus australis australis (the South Island weka) from Nukuwaiata (Chetwode Islands), Pelorus Sound, New Zealand. A novel survey technique (entrance scores) was used in combination with a conventional technique (random searches for active weta) to measure changes in weta population parameters after the removal of predation pressure and to investigate impacts of exotic predators on tree weta. Tree weta density did not increase markedly over the 4-year period, but the proportion of active adults did increase. Weta were observed to move into larger and more crowded galleries (refuges), to occupy galleries closer to the ground, and to spend less time sitting in gallery entrances. It was concluded that endemic tree weta are well adapted to withstand some introduced vertebrate predators but are able to live a more “relaxed” lifestyle in the absence of this predation. The most significant change detected was in weta age structure, with adults increasing their proportion of the population.
The large (4 g) to very large (40 g) stenopelmatid orthopterans of New Zealand are known collectively as weta. A consideration of 20 species of Hemideina, Deinacrida and tusked weta reveals that at one end of a vulnerability gradient are those species which thrive in the presence of key predators (rats), while at the other end are species that have become extinct on the mainland but still survive on predator-free island refuges. Habitat modification does not appear to be a factor in these extinctions. This paper reviews the lifestyles and some important biotic parameters that seem to determine their relative vulnerability along this gradient. When predators are present, the factors leading to extinction are large body size, use of temporary refuges, protective quality of the refuges, time spent on the ground and the effectiveness of their defensive behaviour.
The rare Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), a large flightless insect originally confined to 13ha Middle Island in the Mercury Islands, New Zealand, was last seen there in January 2001. Half-grown or larger insects from a captive-breeding programme were released onto nearby Red Mercury Island (34 ♀, 16 ♂) and Double Island (65 ♀, 19 ♂) in 2000 and 2001 to reduce the potential for accidental extinction. Most (108) were released under individual artificial cover objects (ACOs)—clear Perspex discs under plastic plant-pot saucers—and 26 were placed in artificial holes in soil. Usually <10% were found again under ACOs for up to 18months including
7.5months as adults. Adults, found in 2005 and 2006, were 1st to 3rd generation island-bred weta (lifespan 1.7–3.2years). Ongoing monitoring is planned to confirm long-term success. Inbreeding depression is likely so supplementation from Middle Island is required but they may be extinct there. Scraping the soil to expose weta in underground galleries was the best monitoring method. Few were found by searching with lights at night but adults could be located by following other adults equipped with harmonic radar transponders or micro-transmitters.
To describe the evolution of drug-resistant mutations in patients undergoing treatment interruption strategies. We discuss potential predictors for selecting resistant mutations during treatment interruption.
Current studies on the evolution of drug-resistant mutations during treatment interruption show a low selection frequency for de-novo and archived mutations. The de-novo selection of resistant mutations increases when lamivudine or non-nucleoside reverse transcriptase inhibitor-containing regimens are withdrawn. Although treatment interruption in the context of failing antiretroviral therapy induces the selection of more drug-susceptible strains, resistant virus remains archived and re-emerges once therapy is re-administered, thus thwarting long-term clinical benefits. Alternatively, partial treatment interruption data support the evaluation of treatment strategies aimed at maintaining the benefit of therapy while reducing drug exposure.
The safety and efficiency of treatment interruption strategies remain controversial. The selection of new drug-resistance mutations during treatment interruption is not a key factor in accelerating disease progression when compared with continuous therapy. Conversely, reversion towards more drug-susceptible virus after treatment interruption in heavily treated patients may be accompanied by increased viral pathogenicity, and provides little clinical benefit in subsequent HIV-1 chemotherapy. Partial treatment interruption may be valuable in this context, but larger randomized clinical trials are needed.
A comparative study of the Wellington tree weta, Hemideina crassidens (Blanchard 1851), in the presence and absence of rodents
- C G Rufaut
The ecology of some large weta species in New Zealand In: Field LH (ed) The biology of wetas, king crickets and their allies
- Mcintyre
Habitats and biogeography of New Zealand’s Deinacridinae and tusked weta species In: Field LH (ed) The biology of wetas, king crickets and their allies
- Gibbs
Distribution of alien animals on New Zealand islands The density of indigenous invertebrates on three islands in Breaksea Sound, Fiordland, in relation to the distribution of intro-duced mammals The effects of mammalian predation on invertebrate behaviour in South West Fiordland
- Atkinson
- Iae
- Taylor
- Ag Bremner
- Cf Butcher
- Patterson
- Ag Bremner
- Bip Barratt
- Cf Butcher
- Patterson
Atkinson IAE, Taylor RH (1992) Distribution of alien animals on New Zealand islands. 2nd ed. DSIR land resources contract report, No. 92/59 Bremner AG, Butcher CF, Patterson GB (1984) The density of indigenous invertebrates on three islands in Breaksea Sound, Fiordland, in relation to the distribution of intro-duced mammals. J Royal Soc N Z 14:379–386 Bremner AG, Barratt BIP, Butcher CF, Patterson GB (1989) The effects of mammalian predation on invertebrate behaviour in South West Fiordland. N Z Entomol 12:72–75
Sensory physiology The biology of wetas, king crickets and their allies. CAB International
- Field
- Lh
Field LH (2001) Sensory physiology. In: Field LH (ed) The biology of wetas, king crickets and their allies. CAB International 2001, Wallingford, UK, pp 429–458
Conservation implications of a long-term decline in body condition of the Brothers Island tuatara (Sphenodon guntheri) Introduced predators and avifaunal extinctions in New Zealand Extinctions in near time
- Jm
- S Pledger
- Sn
- Nelson
- Mitchell Nj Nj
- Daugherty
JM, Pledger S, Keall SN, Nelson NJ, Mitchell NJ, Daugherty CH (2006) Conservation implications of a long-term decline in body condition of the Brothers Island tuatara (Sphenodon guntheri). Anim Conserv 9:456–462 Holdaway RN (1999) Introduced predators and avifaunal extinctions in New Zealand. In: MacPhee RDE (ed) Extinctions in near time. Kluwer Academic/Plenum Publishers, Dordrecht, pp 189–238
Beetle records/late Pleistocene of New Zealand. In: Elias SA (ed) Encyclopedia of Quaternary science
- M J Marra
- MJ Marra
Marra MJ (2007) Beetle records/late Pleistocene of New Zealand. In: Elias SA (ed) Encyclopedia of Quaternary science. Elsevier, Amsterdam, pp 236–246
Mating behaviour. In: Field LH (ed) The biology of wetas, king crickets and their allies. CAB International
- Lh
- Jarman
LH, Jarman TH (2001) Mating behaviour. In: Field LH (ed) The biology of wetas, king crickets and their allies. CAB International 2001, Wallingford, UK, pp 317–332
Origin of the offshore islands of northern New Zealand The off-shore islands of New Zealand Proceedings of a symposium convened by the Offshore Islands Research Group in Auckland. Dept of lands and survey information series
- Hayward
- Bw
Hayward BW (1986) Origin of the offshore islands of northern New Zealand. In: Wright AE, Beever RE (eds) The off-shore islands of New Zealand. Proceedings of a symposium convened by the Offshore Islands Research Group in Auckland. Dept of lands and survey information series, No. 16, Wellington, 10–13 May 1983, pp 129–138
Distribution of alien animals on New Zealand islands
- Iae Atkinson
- Rh Taylor
Habitats and biogeography of New Zealand’s Deinacridinae and tusked weta species The biology of wetas, king crickets and their allies
- GW Gibbs
Introduced predators and avifaunal extinctions in New Zealand In: MacPhee RDE (ed) Extinctions in near time
- RN Holdaway
The lost world of the moa: prehistoric life of New Zealand
- TH Worthy
Sensory physiology In: Field LH (ed) The biology of wetas, king crickets and their allies. CAB International
- LH Field
A review of the effect of rodents in New Zealand nature reserves. Dept lands and survey information series
- G W Ramsay
The biology of wetas, king crickets and their allies
- L H Field
- T H Jarman
- LH Field
The lost world of the moa: prehistoric life of New Zealand
- T H Worthy
- R N Holdaway
- TH Worthy