No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Insect Conservation and Islands
Abstract
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.
... Here we present an assessment of the conservation status and threat classification of New Zealand Orthoptera. We follow a recent revision by the New Zealand Department of Conservation (DOC) of the criteria used to classify threatened species (Stringer & Hitchmough 2012; Townsend et al. 2008). ...
... The change for M . isolata resulted from a successful translocation programme ( Stringer & Chappell 2008 ; Watts et al . 2008 ...
... This species has not been seen on Atiu or Middle Island since 2001 despite numerous searches and it may be extinct there ( Sherley et al . 2010 ; Stringer & Chappell 2008 ; Watts et al . 2008 ) . ...
Six New Zealand Orthoptera are considered Threatened: Sigaus homerensis is Nationally Critical; Brachaspis robustus and Sigaus “yellow” are Nationally Endangered; while Sigaus “green”, Sigaus “blue” and Hemideina thoracica with a chromosome arrangement of 2n=23/24 are Nationally Vulnerable. Forty taxa are At Risk comprising one Declining (Sigaus minutus), two Recovering (Deinacrida mahoenui, Motuweta isolata), six anostostomatids that are Relict and 31 Naturally Uncommon taxa. The remaining taxa known to occur in New Zealand comprise eight taxa that are Introducedand Naturalised, 19 that are Data Deficient and 94 taxa, including 80 species, that are Not Threatened. Factors influencing the vulnerability of threatened Orthoptera in New Zealand are noted.
... The results did, however, show that some weta that were released as juveniles grew into adults and that these adults survived for up to 7 months. This indicated that the new habitats could support the weta and this was confirmed because they also reproduced successfully, and by 2006 had passed through up to 3 generations on both islands (Stringer and Chappell 2008). ...
... Both techniques were considered more appropriate for locating tusked weta when they were widely dispersed but when they were present in moderate to high densities the best method for monitoring them was to search plots by scraping the topmost layer of soil off. This revealed the insects in their shallow underground galleries and has the potential to give estimates of absolute density (Stringer and Chappell 2008). Plot searches will now be used on a biennial basis to monitor these populations in the foreseeable future. ...
... While these three weta happened to be among the last tusked weta seen on Middle Island, it is possible they still survive there in very low numbers. However, if they are ever seen again in any numbers on Middle Island, the intention is remove additional breeding stock to supplement the existing populations on Double Island and Red Mercury Island for genetic reasons (Stringer and Chappell 2008). In the meantime, to reduce the extinction risk still further, six individuals from the expanding Double Island population were removed for captive rearing and 200 of their progeny released onto each of Korapuki Island and Stanley Islands (200 individuals onto each island) in the Mercury Island Group during 2007 (Table 1). ...
Establishing new populations by transferring founder individuals from source populations has been effective for managing the
recovery of many threatened species including some weta (Orthoptera: Anostostomatidae) in New Zealand. These large-bodied
flightless insects are ‘flagship species’ for insect conservation in New Zealand and many are rare or threatened. The declining
abundance of most weta species, particularly giant weta, can be attributed to the introduction of mammalian predators, habitat
destruction, and habitat modification by introduced mammalian browsers. New populations of some weta have been established
in locations, particularly on islands, where these threats have been eliminated or severely reduced in order to reduce the
risk of extinction. Some populations were established to provide food for endemic vertebrates, ecosystem restoration and ready
access for the general public. We illustrate how methods for both transferring weta and monitoring them have become more sophisticated
by using a series of case studies. Other transfers of weta not included in the case studies are also summarised. We conclude
by re-iterating the importance of documenting the transfer and post-release monitoring for all insect transfers, both for
biogeographical reasons and to provide information to improve future transfers.
... Captive breeding programmes provide an environment typically free from extinction drivers and provide the opportunity for programme managers to regulate reproduction to retain genetic diversity, and thus increase the likelihood of the successful establishment of new wild populations (Frankham, 1995;Weeks et al., 2015). While most often used for vertebrate species, captive breeding programmes are increasingly used as conservation strategies for invertebrates (Dojnov et al., 2012;Holwell & Andrew, 2015;Honan, 2007;Leather et al., 2008;Pearce-Kelly et al., 1998;Stringer & Chappell, 2008). ...
Captive breeding programmes are key to many threatened species reintroduction strategies but could potentially be associated with adaptations to captivity that are maladaptive in their natural habitat. Despite the importance of sensory ecology to biological fitness, few studies explore sensory system adaptations to captivity. Captive environments are devoid of predators and provide ready access to food sources and potential mates, thus reducing the need for individuals to use signals and cues to identify and locate resources or detect potential threats. With reduced complexity of the signalling environment, relaxation of selective pressures may favour reduced investment in sensory organs in captivity.
We test this prediction in an iconic critically endangered invertebrate, the Lord Howe Island stick insect Dryococelus australis, which was extirpated from the island in the 1920s/30s and rediscovered on a nearby volcanic stack, Ball's Pyramid, in 2001.
Using historical specimens from these populations and specimens from the 8–10th and 14th generations of a long‐term conservation captive breeding programme, we examine differences in behaviourally relevant morphological traits of the compound eyes (visual organs) and antennae (olfactory organs).
We find that captivity is associated with smaller compound eye size, smaller eye ommatidia and reduced density of antennal odour receptors. These morphological changes are indicative of reduced sensitivity to visual and olfactory signals and cues, and therefore are likely to have fitness implications when reintroducing a captive population into the wild.
Synthesis and applications. We observe differences in sensory organ morphology between wild and captive‐bred populations of the critically endangered Lord Howe Island stick insect. Our results emphasise the importance of incorporating evolutionary biology and sensory ecology into conservation programme design: to minimise the potential for captive breeding environments to compromise sensory systems that support appropriate behaviours upon reintroduction of populations into a natural habitat.
... Among the translocated species is the Mercury Islands tusked weta, Motuweta isolata Johns; the entire extant population of which is descended from three individuals. Since then, individuals from a captive breeding program were released successfully onto two islands in the Mercury group (Double and Red Mercury Islands) to reduce the potential for accidental extinction on the only island they were known from originally (Middle Island) and from which they have not been recorded for several years (since January 2001) (Stringer & Chappell 2008). Of the other mammal and avian invaders that predate on native insects, little appears to be known of the extent of their impact on populations, and it ...
Knowledge on the evolution of the New Zealand insect fauna is reviewed and outstanding questions are highlighted. The New Zealand insect fauna is a composite of old and recent lineages and many spectacular examples of evolutionary processes are evident, including species radiations, hybridisation and unusual adaptations. We discuss the origins and evolution of four prominent communities within the insect fauna: terrestrial lowland insects, alpine insects, aquatic insects and insect communities from offshore islands. Within each of these communities, significant lineages are discussed, and in particular the crucial adaptations that enable these lineages to thrive and diversify. Glacial history has had a dramatic impact on the New Zealand insects, and the effects on different lineages are discussed. The New Zealand insects are unique, yet many are threatened with extinction, and efforts to preserve the fauna are reviewed. Despite the accumulating knowledge, major gaps still exist and these are outlined, as are opportunities to address key questions. The review concludes with a synthesis and a discussion of how systematics, new technologies and integrative approaches have the promise to improve dramatically our understanding of New Zealand insect evolution.
... Although patterns of movements and population structure have been determined for other weta (e.g. tree weta, Moller 1985; stone weta, Jamieson et al. 2000; tusked weta, Stringer & Chappell 2008; and giant weta, Watts et al. 2012), no research has been conducted on Hemiandrus species. This study uses a simple and inexpensive tagging method in combination with nightly observations, to determine sexual size dimorphism, and gain new information regarding sex ratios, capture and re-sighting rates and travel distances of H. maculifrons. ...
The ground weta (Hemiandrus maculifrons) is an apparently abundant species with a New Zealand-wide distribution. Despite this, there is a paucity of ecological and biological information concerning this species. We aimed to gain new information about movement patterns, capture rates and body size differences by tagging individuals and conducting nightly surveys of a single H. maculifrons population in the Otanewainuku Forest, Bay of Plenty, New Zealand. Over a 26-night period between March and April 2012, we tagged 53 females and 78 males with queen bee tags and small reflector strips and recorded the location of animals that were subsequently re-sighted. Adult females were significantly larger than males, but capture and re-sight rates suggested males were the more abundant sex during the study period. Female weta moved further over consecutive nights than males (average distance moved, 1.57 m vs. 1.01 m, respectively); however, the tagging method, time of year and study area may have resulted in underestimates. These results indicate areas for further research into aspects of sexual selection, such as potentially biased sex ratios, sexual size dimorphism and mate competition, within H. maculifrons.
... 2012 ) . The successful management involved captive - rearing and translocation to islands near the source island from which introduced predatory mammals had been eradicated ( Stringer & Chappell 2008 ) . Other translocations of threatened invertebrates have also been recently made for conservation purposes but these have yet to affect any threat rankings ( Sher - ley et al . ...
The objectives of the New Zealand Threat Classification System (NZTCS) are summarised together with the methods used to classify taxa as Threatened, At Risk, Data Deficient and Extinct. An analysis is provided of the threat rankings of 3838 New Zealand terrestrial invertebrate taxa that were assessed between 2009 and 2011. Overall, 193 taxa were Threatened with 106 Nationally Critical, 30 Nationally Endangered and 57 Nationally Vulnerable. A further 1055 invertebrates were At Risk comprising 35 Declining, six Recovering, 102 Relict and 912 that were Naturally Uncommon. Another 1208 were Data Deficient, seven were Extinct and 1175 were Not Threatened. The remaining taxa examined were classified as either Introduced and Naturalised (190) or Vagrant (11). Factors and attributes that affect the threat status of New Zealand terrestrial invertebrates are discussed.
... Seddon et al., 2005), especially so on islands (Motala et al., 2007; Gerlach, 2008). For example, a recent special issue of Journal of Insect Conservation, dealing with conservation of island insects (New, 2008), contains only two papers dealing specifically with translocation of insect species as a conservation tool—both on giant weta species in New Zealand (Stringer and Chappell, 2008; Watts et al., 2008), which, admittedly, are also seed dispersers (Duthie et al., 2006). Similarly, very few proposed rewilding projects on islands are specifically aiming at replacing extinct plant species with similar extant ones—and none of these projects seem to have resurrection of lost interactions as the main goal of such substitutions. ...
a b s t r a c t Islands harbour much of the world's threatened biodiversity. Recent work has highlighted how it is not species diversity per se but rather the interactions between organisms that breathes life into ecosystems. Thus, the real challenge to preserving and restoring biodiversity on islands is not to only focus on species themselves, but more importantly on maintaining and restoring the integrity of interactions between the species. Here we argue that mutualistic plant–animal interactions play a pivotal role with regards to conservation and restoration on islands. Furthermore, these interactions are ideally suited for inter-island comparisons due to ecological and evolutionary similarities across geographical and taxonomical boundaries. The similarities include highly generalised mutualistic systems, the evolution and readjustment of plant reproductive traits, and a disharmony in taxonomic groups of mutualists, compared to continental ecosystems. We highlight past and present threats to island plant–animal mutualisms, as well as the challenges and opportunities inherent to these interactions. In particular, we (1) argue that mutualistic networks provide an ideal approach to collect information and advance our knowledge on the systems, (2) suggest the use of interactions as biodiversity monitoring and assessment tools, (3) highlight the differences and similarities between pollination and seed dispersal interactions in the context of restoration, and (4) briefly discuss the ambiguous role of alien invasive species in the management of mutualistic interactions. Finally, we highlight how a recently proposed but controversial restoration strategy, rewilding, can be gainfully applied to and further advanced in island settings.
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.
New Zealand is a world leader in saving species from the brink of extinction. We selected seven case studies to explore successful species conservation in New Zealand over the past 30 years to exemplify what makes a ‘conservation winner’. The taxa chosen were: Hebe armstrongii, Mercury Islands tusked wētā, Galaxias vulgaris, tuatara, saddleback, long-tailed bat and humpback whale. Three of the case studies (hebe, wētā, galaxiids) illustrate the lack of attention compared to birds, possibly limiting conservation achievements. Considerable attention has gone into the development of species-specific techniques, including captive breeding and translocation protocols, and genetic studies to define management units. All case studies demonstrated the need for continued conservation attention, as long-term success is not guaranteed. We believe by accentuating the positive outcomes of conservation, the wider community will realise that efforts to save endangered species have the potential to reverse the current extinction crisis facing the world.
The Tiger Spiketail dragonfly (Cordulegaster erronea Hagen) is geographically restricted to the eastern half of North America, patchily distributed within the range and a habitat specialist of small spring and seepage fed headwater streams running through mature forest. These habitats are highly sensitive to disturbance and the Tiger Spiketail is of conservation concern throughout most of its range. Yet little is known about the habitat use of either sex away from the breeding stream hampering conservation strategies. In this study we use miniaturized radio transmitters to investigate the habitat use and home range of individual males and a female Tiger Spiketail in New Jersey. This is the first and only radio-telemetry for this species. We also provide recommendations for habitat protection and conservation. Our studies demonstrate that this species is critically dependent upon mature forest and the high quality, perennial headwater streams that run through them. These habitats are particularly sensitive to disturbance. Except when patrolling and ovipositing, both sexes are in the canopy above the breeding stream and in the adjacent mature forest, indicating the inseparable linkage between the aquatic and forested terrestrial habitat for this species. Our observations also suggest that C. erronea occurs in a metapopulation of nearby streams in our study area. Conservation of this species may therefore require forest protection far beyond the breeding stream. In New Jersey, and in other places throughout the range, there are many potential pressures on these habitats and current regulatory protections are not likely suitable. These same habitats may also be important for other Odonate species of conservation concern suggesting that protection of C. erronea may benefit a suite of species. We hope the information obtained from this study can assist resource managers in developing conservation and habitat protection measures.
Between 1997 and 2003 mortality and yearly movements including homing (philopatry) of long-lived Placostylus ambagiosus and P. hongii land snails were studied when left in situ or exchanged between nearby sites in New Zealand. Harmonic radar transponders, attached to shells, increased recapture rates but might have increased emigration. Manipulation (translocation exchanges vs. control) caused no detectable changes but sample sizes were small. At Cape Maria van Diemen, 20% of P. ambagiosus homed after translocation although 90% died during widespread mortality. No P. ambagiosus snails homed at Surville Cliffs where 2.4% died and 26% emigrated. At Whareana Bay, 23% homed, 19% died, 8%–15% stayed where released and 58% emigrated. Mortality of P. hongii on Tawhiti Rahi Island, Poor Knights Islands, was 2% after 1 year. When transferred 10–84 m, 78% homed within a year, 2% went elsewhere and 20% were not found. However, 24% of those transferred 30–84 m returned to their release sites after homing. When left in situ, 60% remained nearby, 8% moved elsewhere and 30% were not found. There was an indication that habitat quality might influence emigration. Results are briefly discussed in relation to possible future translocations to conserve genetic variability and restore faunas.
The species richness of orthopteroid insects (grasshoppers/bush-crickets and earwigs) and the incidence of Gortyna borelii lunata (Freyer) on an island nature reserve were compared with mainland sites to determine the value of offshore habitats in the Walton Backwaters in eastern England. The species richness of orthopteroid insects was significantly different between Skippers Island and the mainland study sites. The flightless Leptophyes punctatissima (Bosc) and the nationally scarce Forficula lesnei (Finot) were restricted to offshore habitats. The favourability of Skippers Island for orthopteroids may be due to the absence of intensive agricultural management and livestock grazing, which has led to the development of tussocky grassland and scrub. Despite a high density of its larval foodplant, Peucedanum officinale (L.), there was not a significantly greater incidence of larval feeding signs of G. borelii lunata on Skippers Island. Insects reliant on the island (such as F. lesnei) may be susceptible to the loss of coastal populations due to sea level rise, particularly as the sea wall flood defence on Skippers Island is poorly maintained and eroding quickly.
Terrestrial invertebrates constitute the majority of life on Earth. Taxonomic impediment affects our ability to identify invertebrates, and their polymorphism compounds the problem. The principal threats to their survival are habitat loss and fragmentation; isolated habitats are particularly vulnerable to anthropogenic impact; climate change has synergistic effect with the habitat fragmentation. Invasive species have caused declines of invertebrates, especially in insular habitats.Conservation of invertebrates can be divided into coarse and fine filter approaches. Habitat conservation is the most effective tool, but recovery programs can be developed.
Captive rearing can be a successful short-term strategy for protecting species threatened with extinction, by bolstering existing populations, or establishing new ones. Improving the success of captive rearing requires specific prior ecological knowledge, for example habitat and climatic requirements. Here, we report on the captive rearing of the critically endangered Canterbury knobbled weevil Hadramphus tuberculatus (Pascoe, 1877). Only a single population of H. tuberculatus is known, with an estimated population size of fewer than 100 individuals; as such, captive rearing provides an opportunity to augment the remaining population and potentially to allow the establishment of new populations, if suitable sites can be found. We successfully reared two F1 generation adults and two live larvae were recovered at the end of the project. We use a qualitative spatial analysis to determine the location of possible sites for reintroduction of H. tuberculatus. The spatial analysis suggests that there is little suitable habitat remaining for new H. tuberculatus populations. Our study provides guidelines for future captive breeding programmes and highlights the risks of removing individuals from an already vulnerable, small population.
New Zealand's offshore islands are refuges for many threatened species, a high proportion of vertebrate diversity, and the world's most diverse fauna of seabirds. We present key issues and questions that can be used to guide research on the conservation of biodiversity on these islands. Four global reviews formed a basis from which we identified research questions of potential relevance to the management of these islands. The research questions were assigned in the context of nine objectives proposed as a means of achieving ecological integrity. For each of the nine objectives, we then asked what has been achieved in terms of island research and management, and what needs to be achieved in order to meet long-term goals. We used local examples to identify issues and questions specific to the islands of New Zealand. Our analyses revealed two research areas in which current understanding is poor. One is the need to understand ecosystem processes and their resilience to long-term environmental change. The second is the need to define and better understand the consequences of direct involvement by the public in the management of islands, including partnerships between government agencies, tangata whenua (original people of the land - Māori) and non-government organisations such as community groups. © New Zealand Ecological Society.
The exciting prospect of discovering New Zealand's untapped insect fauna was incentive enough for the early collectors of natural history specimens. Investigation of the fauna began with Joseph Banks on the Endeavour in 1769 and was continued by a devoted group of eighteenth century naturalists who occasionally voiced their concern at the rate of destruction and modification of the indigenous ecosystems as European Imperialism fuelled the development of agriculture for the economic base of the new colony. Although records are sparse, at least two early entomologists expressed their opinions in the early twentieth century. G.V. Hudson aired his concern about the dwindling numbers of native insects in a Presidential Address to the Wellington Philosophical Society (Hudson 1900) and later recollected that: 'every summer throughout the eighties great fires raged on the hills around Wellington and the air was thick with smoke for days together'. The concept of preserving native fauna was then in the minds of very few and those who protested at the reckless destruction of the forest were regarded as cranks. (Hudson 1950, pp. 161-162). Back 'home' in Britain, another entomologist, Commander James J. Walker (1921) in his presidential address to the Entomological Society of London, also drew attention to the potential plight of New Zealand's insect fauna when, after discussing the rich and endemic attributes of the flora that were being lost both to agriculture and weed invasion, he said that 'the disastrous effect on all forms of life of this destruction and replacement (necessitate) immediate and thorough research in what still remains of the endemic animal life of New Zealand, before many of its most interesting forms are lost forever.' However, nothing was done and no consideration was given to the need to conserve invertebrates. Instead, it was the ornithologists who paved the way for the first conservation ethic as they focussed on New Zealand's unusual and dominant bird life. This began with the influential politician, Thomas Potts, who raised awareness for conservation in the 1850s and was eventually in part responsible for the declaration of island reserves for Resolution, Secretary, Little Barrier, and Kapiti islands, gazetted between 1891 and 1897 (Young 2004). Conservation action on behalf of invertebrates did not occur despite increasing knowledge of their uniqueness and significance in understanding southern biogeography issues (Gibbs 2006). © 2012 Springer Science+Business Media Dordrecht. All rights are reserved.
There are few suitable monitoring tools for assessing the effectiveness of management for threatened insect taxa. This is especially true for cryptic arboreal species of nocturnal flightless orthopterans in the genus Deinacrida from New Zealand. Systematic searching of habitat during the day was compared with footprint tracking tunnels baited with peanut butter as methods for monitoring the arboreal giant weta Deinacrida heteracantha and Deinacrida mahoenui (Orthoptera: Anostostomatidae). Searching by day required more time (3h per transect) than operating tracking tunnels (1.4h). Lines of 30–35 tracking tunnels spaced 30 m apart could be quickly set to sample large areas. Searching may provide additional information including the species, age class, and sex, whereas tracking tunnels yield presence/absence data for giant weta that were larger than other anostostomatid present. Both methods provide indices of relative abundance: it is impractical in tall forest to accurately estimate absolute density whereas tracking tunnel results are related to the activity of weta. Weta activity may depend on vapour pressure deficit modulated by the temperature. For conservation and monitoring purposes, we recommend that tracking tunnels be used first to detect giant weta and only then search for them if further data is required.
The Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), survived only on
13 ha Ahu or Middle Island, a mammal-free island in the Mercury Group, New Zealand. Between 2000 and 2009, 567 individuals were translocated in nine releases to six nearby islands from which mammals had been removed. These translocations occurred to reduce the chance of accidental extinction of the Middle Island population of only a few hundred adults and to contribute to the restoration of the other islands. All translocated insects originated from the captive-bred progeny of one male and two females collected from Middle Island between 1998 and 2001. Their establishment on Double and Red Mercury Islands, after their releases in 2000 and 2001 respectively, was confirmed by searching plots, and by using footprint tracking tunnels on Red Mercury Island between 2008 and 2012. Tracking tunnels provided better data and proved more cost effective than searching plots for detecting large tusked weta. Tracking tunnels demonstrated that the population
on Red Mercury expanded outwards from the release sites by 50–100 m each year between 2009 and
2012. These weta are now estimated to be present over more than half the Island. Tusked weta have also survived on Stanley, Korapuki and Ohinau Islands after releases in 2007, but they remain within 100 m of the release sites. No confirmed progeny of the weta released on Cuvier Island in 2008 and 2011 were detected. No tusked weta were detected on Middle Island using tracking tunnels on eight occasions between 2009 and 2012, suggesting this species is likely to be locally extinct. Despite possible failure on one island, these translocations have resulted in a significant conservation success outcome.
Radio telemetry has been widely used to study the space use and movement behaviour of vertebrates, but transmitter sizes have only recently become small enough to allow tracking of insects under natural field conditions. Here, we review the available literature on insect telemetry using active (battery-powered) radio transmitters and compare this technology to harmonic radar and radio frequency identification (RFID) which use passive tags (i.e. without a battery). The first radio telemetry studies with insects were published in the late 1980s, and subsequent studies have addressed aspects of insect ecology, behaviour and evolution. Most insect telemetry studies have focused on habitat use and movement, including quantification of movement paths, home range sizes, habitat selection, and movement distances. Fewer studies have addressed foraging behaviour, activity patterns, migratory strategies, or evolutionary aspects. The majority of radio telemetry studies have been conducted outside the tropics, usually with beetles (Coleoptera) and crickets (Orthoptera), but bees (Hymenoptera), dobsonflies (Megaloptera), and dragonflies (Odonata) have also been radio-tracked. In contrast to the active transmitters used in radio telemetry, the much lower weight of harmonic radar and RFID tags allows them to be used with a broader range of insect taxa. However, the fixed detection zone of a stationary radar unit (< 1 km diameter) and the restricted detection distance of RFID tags (usually < 1-5 m) constitute major constraints of these technologies compared to radio telemetry. Most of the active transmitters in radio telemetry have been applied to insects with a body mass exceeding 1 g, but smaller species in the range 0.2-0.5 g (e.g. bumblebees and orchid bees) have now also been tracked. Current challenges of radio-tracking insects in the field are related to the constraints of a small transmitter, including short battery life (7-21 days), limited tracking range on the ground (100-500 m), and a transmitter weight that sometimes approaches the weight of a given insect (the ratio of tag mass to body mass varies from 2 to 100%). The attachment of radio transmitters may constrain insect behaviour and incur significant energetic costs, but few studies have addressed this in detail. Future radio telemetry studies should address (i) a larger number of species from different insect families and functional groups, (ii) a better coverage of tropical regions, (iii) intraspecific variability between sexes, ages, castes, and individuals, and (iv) a larger tracking range via aerial surveys with helicopters and aeroplanes equipped with external antennae. Furthermore, field and laboratory studies, including observational and experimental approaches as well as theoretical modelling, could help to clarify the behavioural and energetic consequences of transmitter attachment. Finally, the development of commercially available systems for automated tracking and potential future options of insect telemetry from space will provide exciting new avenues for quantifying movement and space use of insects from local to global spatial scales.
New Zealand's offshore and outlying islands have long been a focus of conservation biology as sites of local endemism and as last refuges for many species. During the c. 730 years since New Zealand has been settled by people, mammalian predators have invaded many islands and caused local and global extinctions. New Zealand has led international efforts in island restoration. By the late 1980s, translocations of threatened birds to predator-free islands were well under way to safeguard against extinction. Non-native herbivores and predators, such as goats and cats, had been eradicated from some islands. A significant development in island restoration in the mid-1980s was the eradication of rats from small forested islands. This eradication technology has been refined and currently at least 65 islands, including large and remote Campbell (11 216 ha) and Raoul (2938 ha) Islands, have been successfully cleared of rats. Many of New Zealand's offshore islands, especially those without predatory mammals, are home to large numbers of breeding seabirds. Seabirds influence ecosystem processes on islands by enhancing soil fertility and through soil disturbance by burrowing. Predators, especially rats, alter ecosystem processes and cause population reductions or extinctions of native animals and plants. Islands have been promoted as touchstones of a primaeval New Zealand, but we are now increasingly aware that most islands have been substantially modified since human settlement of New Zealand. Archaeological and palaeoecological investigations, together with the acknowledgement that many islands have been important mahinga kai (sources of food) for Māori, have all led to a better understanding of how people have modified these islands. Restoration technology may have vaulted ahead of our ability to predict the ecosystem consequences of its application on islands. However, research is now being directed to help make better decisions about restoration and management of islands, decisions that take account of island history and key drivers of island ecosystem functioning.
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.
Appropriate monitoring tools are essential for assessing the effectiveness of management for all threatened insect taxa. In
New Zealand the large-bodied flightless orthopterans in the genus Deinacrida have mostly been monitored by searching through habitat during the day or spotlighting at night but this is time consuming
and the results depend on the skill of the searcher. Recently, footprint tracking tunnels, similar to those used for monitoring
small mammals in New Zealand, were found to be effective for detecting adults of various giant weta species. In this study,
we compared the abundance of Cook Strait giant weta (CSGW) in the vicinity of the tunnels, estimated by mark-recapture, with
the number of tracking tunnels tracked by weta. We found strong indications that both baited and unbaited tracking tunnels
can be used to estimate the number of adult weta present but that this probably depends on their responses to meteorological
conditions which are not yet understood. Our results also show that footprint tracking tunnels are more effective for detecting
adult CSGW than searching for these insects at night and that baiting tracking tunnels with peanut butter increases their
effectiveness for detecting adult CSGW. We confirmed how far Cook Strait giant weta moved each night on Matiu-Somes Island
by attaching transmitters to them and found that day roosts of three adult males were on average 8.6m apart each day and
those of adult females were on average 21.3m apart. Both the low recapture rates of marked adult CSGW and the nightly displacements
of those with transmitters suggest that adult CSGW show no site fidelity and are clearly capable of moving large distances
each night. However, an individual weta is unlikely to track more than one tunnel per night if tunnels are 30m apart. Tracking
tunnels have the potential to be used with some other insects, provided their footprints are diagnostic. An advantage of using
tracking tunnels is that they are non-lethal and would therefore be particularly suitable for monitoring other large threatened
insect taxa.
KeywordsConservation–Monitoring tool–Tracking tunnels–Threatened taxa
Landscape changes can affect species richness, population density, and condition of animals. We initiated an investigation of snakes in southeastern New Hampshire because we speculated that this taxon would be responsible to recent land-use changes. Species richness, relative abundance, and size distribution of snakes were the parameters we were interested in sampling by capturing snakes on a series of habitat patches. We considered various capture methods and compared the effectiveness of plastic cover sheets and drift fence-trap configurations to sample local snake populations. More species were captured with drift fence-trap configurations. Size distributions of snakes differed by method of capture, with cover sheets yielding proportionately more small-bodied snakes. Cover sheets were less expensive to construct, maintain, and remove than were drift fence-trap configurations. Additionally, fewer mortalities of snakes and nontarget vertebrates were associated with cover sheets. Microclimates under sheets likely attracted potential prey and snakes to cover sheets. Although cover sheets were effective to sample snakes in early successional sites, multiple techniques may be needed in more heterogeneous habitats.
Middle Island is unusual for a northern New Zealand island in that it lacks recent human modification and is rat-free. Observations and plant records are compared with Atkinson's botanical survey of the island 21 years earlier. Regeneration in a recent wind-throw area, milk tree (Streblus hanksii) forest age, and weed status are discussed. Ninety-six vascular plant species are recorded in an appended annotated species list for the island and three associated islets; over 70% of these records are vouchered. A bryophyte list of 11 species is included in the Appendix.
The Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), occurs naturally only on Middle Island, a 13 ha island in the Mercury Island group, New Zealand. Growth and development were studied to support a conservation programme to establish them on two other islands and thereby reduce chances of accidental extinction. The egg incubation period was determined from 784 eggs laid by eight weta (range 6-275 eggs per female) exposed to varying temperature similar to Middle Island. Most eggs (240) hatched after 12-39 weeks but 17 eggs laid in late winter hatched after 48-63 weeks. Overall, 87% hatched between October and December, and all hatched between August and February. Egg mortality was 67% (range 50-100% for individual females). Growth and postembryonic development was observed in the laboratory at 16-18°C, and a 14 : 8 h (light : dark) photoperiod. Males and females became adult at either the 10th or 11th instar. Lengths of the head, head with jaws, pronotum, protibia, tympanal membranes, mesotibia, metatibia, metafemur, cercus, ovipositor, tusks, hypandrium and stylus are given for each instar. Tusks appeared as slight bulges on the mandibles of males at the 7th instar, and subsequently enlarged allometrically at each ecdysis. The lifespan from hatching averaged 718 ± 51 d (±95% CI) and ranged from 595 to 902 d. No significant differences were detected between the lifespans of either males or females, or weta that became adult at the 10th or 11th instar. Adult status was confirmed for one 10th instar male when it copulated with 11th instar adults. Males made multiple unsuccessful attempts to copulate with two 10th instar females and 284 eggs were found in one 10th instar female after it died. Only one 11th instar female laid eggs (83) but none hatched in the laboratory.
Importations of biological control agents for insect pests and weeds in New Zealand are summarized and factors contributing to the relative success of the programmes are examined. The establishment rate of 30.9% is similar to that achieved worldwide, but is significantly lower than the rate achieved in the island habitat of Hawaii. The pioneering role of New Zealand in biological control is shown by the high proportion of programmes first attempted in this country. Although this novelty has not reduced the establishment rate, introductions against endemic species have not succeeded. Size of release was not a dominant feature in the establishment of agents. Complete or substantial success is recorded for 17 of the 70 target pests, with a relatively high success rate in forestry programmes. Examples of the influence of climate matching and competitive exclusion are also discussed. Changing practices and attitudes to the introduction of biological control agents are documented to show the increasing emphasis on specialists. No adverse effects of introductions are reported. The challenge to practitioners and regulators is to develop systems to evaluate conflicts of interest and develop workable mechanisms to determine which biological control agents are suitable for release.
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.
Absract: Mountain stone weta (Hemideina maori) on the Rock and Pillar Range in the South Island, New Zealand, are found primarily in cavities under flat rocks on isolated outcrops or 'tors'. We marked 66 adult weta on one tor and 30 adults on an adjacent tor and recorded their location during the summer and for the following three years to obtain baseline data on survival, longevity, dispersal, and movement within tors. It was not uncommon for adult weta to live for two to three years. Most marked weta were resighted at least once, usually under the same rock. Few weta moved further than the rock adjacent to where they were first captured and only one dispersed to a neighbouring tor. On one tor, a relatively stable group of 6-8 females and 2 males was resighted during most of the summer period under one large rock. An analysis of our mark-recapture methodology and results indicates that H. maori may be an appropriate species for investigating population structure in a metapopulation context as well as local mate competition.
Tree weta (Hemideina) are an important component of New Zealand forest ecosystems and have been identified as possible invertebrate indicator species in restoration programmes. We present designs for artificial weta roosts that have been used to monitor tree weta in Hawke's Bay for five years. A variety of invertebrates use the roosts including two species of Hemideina. Our data suggest that occupation of roosts may take a number of years, each roost monitors a very limited area, and that occupation by invertebrates fluctuates seasonally. We recommend that data from weta roosts be used primarily for temporal rather than spatial comparisons, and that installation of roosts takes place as far ahead of changes in management as feasible.
Artificial retreats are increasingly used to sample animal populations and in attempts to boost animal numbers in degraded habitats. Understanding how animals use artificial retreats and which designs are most effective is therefore important. We tested the influence of retreat type, time-of-year and site on the use of artificial retreats by three species of terrestrial lizards (McCann's skink Oligosoma maccanni, common skink O. nigriplantare polychroma, and common gecko Hoplodactylus maculatus) in a remnant of grazed coastal shrubland at Birdlings Flat, New Zealand. Monthly capture sessions took place at two sites between December 2003 and November 2004. During 2160 retreat checks, 898 captures of 388 individual lizards were made. Geckos dominated the sample and displayed strong preferences for artificial retreats made of Onduline over corrugated iron and concrete tiles. Skinks used all types of artificial retreats without apparent preference. For all species, use of artificial retreats varied with time-of-year and was lowest in winter months. We also operated pitfall traps at these sites and made 329 captures of 205 individuals during 1920 trap-checks. Pitfall traps produced samples dominated by skinks. We conclude that Onduline retreats are a promising method for detecting terrestrial species of gecko in open habitats. Long-term studies are required to quantify the benefits of providing artificial retreats in restoration projects.
Relocations of species have become a tool widely used in nature conservation, but insects have rarely been considered as targets. Here, we present a translocation project of the field cricket (Gryllus campestris L. 1758), which is a threatened species at the northern edge of its range. Only ten populations were left in Lower Saxony (Germany), illustrating the need for urgent conservation measures. After 10 years of monitoring and management of an isolated population, 213 nymphs were captured and released at another nature reserve in summer 2001. The size of the new population increased significantly from 27 singing males in spring 2002 to 335 singing males in spring 2005. The occupied area increased from 5.66 ha to 33.14 ha. Altogether, the translocation project was evaluated as successful, but the inland dune proved to be not as suitable for the species as initially expected. Our results indicate that translocations of highly reproductive insect species are prom-ising, as long as the release locality contains sufficiently large areas of suitable habitat and a high number of wild juveniles from a closely located and large source population are released in a climatically favorable period. Management and resto-ration of habitats, as well as continuous monitoring are of crucial importance for the success of the translocation project. Moreover, the importance of a high quality of cooperation between conservationists, authorities, foresters, farmers, financiers and scientists cannot be overstated. Translocation of an endangered insect species, the field cricket (Gryllus campestris Linnaeus, 1758) in northern Germany
Invasions by non-native ants are an ecologically destructive phenomenon affecting both continental and island ecosystems throughout the world. Invasive ants often become highly abundant in their introduced range and can outnumber native ants. These numerical disparities underlie the competitive asymmetry between invasive ants and native ants and result from a complex interplay of behavioral, ecological, and genetic factors. Reductions in the diversity and abundance of native ants resulting from ant invasions give rise to a variety of direct and indirect effects on non-ant taxa. Invasive ants compete with and prey upon a diversity of other organisms, including some vertebrates, and may enter into or disrupt mutualistic interactions with numerous plants and other insects. Experimental studies and research focused on the native range ecology of invasive ants will be especially valuable contributions to this field of study.
Although reproductive and behavioural studies have been conducted on captive tree weta, there have been very few ecological field studies of any of the weta species involving free-ranging, marked individuals. The mountain stone weta (Hemideina maori) is a tree weta that lives on rock tors in the alpine region of the South Island of New Zealand. Over three seasons each of 480 adults and 789 juveniles was individually marked on four large and 14 small tors to gather baseline information on aspects of H. maori's life cycle and life history. Seasonal patterns were seen in the appearance of the smallest nymphs, moulting, and in the survival and recruitment of adults. Some marked juveniles were recaptured after 10 or more months, with a maximum interval of 14.1 months, indicating that instar intervals can be exceptionally long. Adult males and females had similar survival rates and often lived for 2 or 3 breeding seasons. Relatively high recapture rates (~60–70%) and long life spans make adult H. maori amenable to modern mark-recapture analyses using the programme MARK. We believe this research will be a useful template for further mark-recapture studies such as those to verify life history characteristics of endangered species of weta or the effects of secondary poisoning on invertebrates.
Mercury Islands tusked weta, Motuweta isolata, is a rare insect found naturally only on 13-ha Middle Island (official name now Atiu or Middle Island) in the Mercury Islands, northern New Zealand. The New Zealand Department of Conservation is attempting to establish additional populations of this weta on two other mammal-free islands in the Mercury Islands to enhance its long-term survival prospects. Morphological characters were needed to distinguish between juveniles of M. isolata and a ground weta, Hemiandrus pallitarsis, which is common on Middle Island and which closely resembles M. isolata. The best
character was the number of posterio-dorsal spines on the mesotibia: M. isolata has two and H. pallitarsis has three. Protibial tympanal organs are present only in 2nd instar and older M. isolata but were hard to distinguish (using a hand lens) from subgenual organs in small H. pallitarsis. Adult female H. pallitarsis also
possess a unique elongated bilobed process between the 6th and 7th abdominal sternae. If accurate field measurements of the pronotum, protibia, and metafemur are made, many weta can be identified later using quadratic discriminant analysis. Four Mercury Islands tusked weta were found during 65 nights of searching on Middle Island between October 1998 and April 2003. These individuals were active on nights with little or no wind, little or no moonlight, temperatures 15.9–19.2°C, and relative humidity > 87.4%. Mercury Islands tusked weta translocated from captivity to Double Island (Moturehu) and Red Mercury Island (Whakau),
were active on nights with similar conditions—temperatures 11.5–20.5°C, and relative humidity > 79%. The use of baited traps, oviposition trays or artificial cover objects on Middle Island did not improve detection of tusked weta. A total of 717 ground weta were found. They were active at temperatures > 9°C and
relative humidity > 60%. The number of weta observed on any particular night had a significant non-linear relationship with soil temperature, soil moisture content and air temperature, but was independent of rainfall, saturation vapour deficit or relative humidity.
Between 1968 and 1983, 22 species of dung beetles from southern Africa were released into pastoral regions of Queensland in
northern Australia. Seven species have become widespread and abundant and the others either occur in isolated patches, are
rare or have failed to establish self perpetuating populations. These species all occur in the Hluhluwe district in southern
Africa which has a climate similar to that of coastal central and southern Queensland. The numberical abundance and habitat
associations of the 22 speices were examined at Hluhluwe to seek an explanation for their performance in Australia. It was
concluded that habitat specificity and the adequacy with which habitat was matched in Australia were critical factors. Species
which established in Australia were relatively common in cattle dung in Africa where they showed a preference for grassland
on clay-loam soils.
Entre 1968 et 1983, 22 espèces de bousiers originaires du sud de l'Afrique ont été lâchées dans des régions d'élevage du Queensland,
dans le nord de l'Australie. Sept espèces se sont bien dispersées et sont devenues abondantes: certaines vivent dans des zones
discontinues, d'autres enfin sont rares ou n'ont pas réussi à s'établir de façon durable. Ces 22 espèces sont présentes das
le district d'Hluhluwe, dans le sud de l'Afrique, où le climat est analogue à celui de la partie centrale et méridionale de
la Côte du Queensland. L'abondance numérique et les caractéristiques du biotope de ces espèces ont été examinées à Hluhluwe
pour essayer d'expliquer le résultat de leur introduction en Australie. Il s'avère que la spécificité dans le choix de l'habitat
et la convenance du nouvel habitat sont les facteurs critiques du succès. Les espèces qui se sont établies en Australie étaient
relativement communes dans les bouses du bétail d'Afrique, où elles montraient une préférence pour les prairies sur sol lourd-argileux.
Summary Males ofLigurotettix spp. grasshoppers (Orthoptera, Acrididae, Gomphocerinae), territorial species that defend individual host plant shrubs, home to their territories by memorizing landmarks. Thus, the insects can navigate efficiently toward high quality shrubs which are chemically distinctive and recognizable via gustation, but indistinguishable from a distance.
Ecology is a subject where theoretical predictions are often difficult to test experimentally in the field. To address this challenge, the Ecological Society of America suggested exploiting large-scale environmental management decisions in a scientific way. This 'adaptive management' constitutes one of the purposes of the Sustainable Biosphere Initiative. Meanwhile, in the current context of the biodiversity crisis, translocations and particularly reintroductions of threatened species are becoming more numerous. It is time for ecologists and wildlife managers to collaborate on these unique opportunities for large-scale studies.
1. The UK Biodiversity Action Plan (UKBAP) identifies invertebrate species in danger of national extinction. For many of these species, targets for recovery specify the number of populations that should exist by a specific future date but offer no procedure to plan strategically to achieve the target for any species.
2. Here we describe techniques based upon geographic information systems (GIS) that produce conservation strategy maps (CSM) to assist with achieving recovery targets based on all available and relevant information.
3. The heath fritillary Mellicta athalia is a UKBAP species used here to illustrate the use of CSM. A phase 1 habitat survey was used to identify habitat polygons across the county of Kent, UK. These were systematically filtered using relevant habitat, botanical and autecological data to identify seven types of polygon, including those with extant colonies or in the vicinity of extant colonies, areas managed for conservation but without colonies, and polygons that had the appropriate habitat structure and may therefore be suitable for reintroduction.
4. Five clusters of polygons of interest were found across the study area. The CSM of two of them are illustrated here: the Blean Wood complex, which contains the existing colonies of heath fritillary in Kent, and the Orlestone Forest complex, which offers opportunities for reintroduction.
5. Synthesis and applications. Although the CSM concept is illustrated here for the UK, we suggest that CSM could be part of species conservation programmes throughout the world. CSM are dynamic and should be stored in electronic format, preferably on the world‐wide web, so that they can be easily viewed and updated. CSM can be used to illustrate opportunities and to develop strategies with scientists and non‐scientists, enabling the engagement of all communities in a conservation programme. CSM for different years can be presented to illustrate the progress of a plan or to provide continuous feedback on how a field scenario develops.
We conducted a field study to evaluate whether coverboards are as effective for sampling terrestrial salamanders as searching natural cover objects such as fallen logs and branches. At each of five sites in Jenkins County, Georgia, we paired a grid of 100 wooden coverboards (30.4 × 30.4 × 2 cm) placed 10 m apart with an adjacent grid containing only natural debris. Searches under coverboards detected most of the same species (Plethodon ocmulgee, Eurycea cirrigera, Eurycea quadridigitata, and Eurycea guttolineata) as found under natural cover (same four species plus Ambystoma opacum). However, salamanders were encountered at lower average rates under coverboards (0.8 salamanders per grid search) than under natural cover (2.3 salamanders per grid search), and this pattern was consistent across seasons. The number of salamanders encountered was more variable within coverboard grids than within grids of natural cover; mean encounter rates were equally variable among grids for the two techniques. For the most commonly encountered species (P. ocmulgee), individuals from coverboards were similar in size to those found under natural cover. There was no tendency for coverboards to accumulate more salamanders through time. Temperatures were more variable under coverboards than under natural cover.
The biology of the endangered Middle Island tusked wētā (Motuweta isolata) was investigated using captive-reared wētā. The project aimed to develop a reliable captive-rearing method for the Middle Island tusked wētā in order to produce sufficient numbers to enable releases to be made on islands neighbouring its sole island home-Middle Island-in the Mercury Islands, North Island, New Zealand. Micro-habitat conditions were measured in wētā habitat on Middle Island, and at a proposed release site on Double Island. Data on developmental rates, mortality, oviposition substrate preference, fecundity, and behaviour were recorded for captive Middle Island tusked wētā. Conditions leading to successful breeding in captivity were recorded. This project followed on from a previous project, which identified several factors affecting breeding success. Resulting modifications to the rearing method succeeded in reducing the mortality of juveniles and adults, and in improving oviposition success and egg hatch-rate.
Remnant wild Capra hircus maintained social groups and fixed home ranges. This provided opportunities for group eradication once feral goats accepted a radio-collared individual, and when the radio-collared goat and its cohorts could be relocated repeatedly in Hawaii Volcanoes National Park backcountry. -from Authors
The ensiferan family Anostostomatidae, formerly included in the Stenopelmatidae, or called the Henicidae or Mimnermidae is diagnosed and a world checklist of species is presented. Some longstanding nomenclatural problems are resolved through examination of most of the types and many new synonyms at the generic and species levels are presented. Two new monospecific genera are eastablished for species in Australia and New Zealand: Transaevum laudatum and Motuweta isolata
The successful ‘Judas’ goat technique has been adapted for use
with feral pigs. The ‘Judas’ goat technique involves releasing
radio-collared goats into a control area and, after a sufficient period to
allow them to join other goats, tracking them down and culling the other
individuals associated with them.
Trials with the technique on feral pigs in Namadgi National Park, ACT,
indicated that it worked best with sows captured in the same area. Each of
these sows established contact with 1–8 other pigs in the area within
1–7 days of release and was located with at least one other pig on
67–100% of occasions. In contrast, sows and boars from outside
the study area took longer to come into contact with ‘local’ pigs
and associated with them much less frequently.
A subsequent control exercise in Namadgi, using ‘Judas’ pigs to
indicate where to lay warfarin baits from a helicopter, resulted in a
75% reduction in the low-density population still present after a
larger control exercise two years earlier. Since then, the technique has been
used to eradicate a small colony of feral pigs in central Australia and is
proving successful for control of feral pigs and other ungulates in other
parts of Australia and New Zealand.
Gryllacridid ensiferans (Orthoptera : Gryllacrididae) appear to display a
degree of nest-site fidelity comparable to that of most social insects. The
nesting behaviour of juvenile gryllacridids was studied to determine when
nests were first built and whether juveniles were able to subsequently
recognise their own nests. Additionally, the hypothesis that juvenile
gryllacridids could orient to their nest over distance by chemical means was
examined via a directional choice experiment within a simple olfactometer.
Juveniles of a known ‘nest-building’ gryllacridid constructed
nests within days of hatching, reflecting current ideas that nesting is an
integral component of gryllacridid biology. Such nests were occupied
preferentially over extended periods. Furthermore, individual juveniles were
capable of recognising their own nest from that of their conspecifics. Such a
result supports recent findings of an individual/nest-specific chemical
odour amongst adult gryllacridids. However, the results provide no evidence
that juvenile gryllacridids are able to detect the presence of their own nest
over any substantial distance and some mechanism other than chemically based
orientation is necessary to explain the apparent homing ability of these
orthopterans.
The mechanisms of nest building and relocation were examined in Hyalogryllacris sp. 14 (Orthoptera: Gryllacrididae). This nocturnal, thigmotactic species readily constructed silken nests in artificial shelters or 'tents'. The architecture and silk density of nests did not differ significantly between individuals, although nests of males contained significantly more silk that those of females. Disturbing the insects during photophase elicited defensive displays. Gryllacridids reoccupied their original nest significantly more often than an empty tent or the nest of a conspecific, after a night of foraging in a laboratory arena. When offered heat-treated (80 degrees C for 2 h) nests, gryllacridids showed a significant preference for those with greater amounts of silk. The heating (chemical cue elimination), tearing (tactile cue elimination), and heating-tearing of an insect's nest significantly reduced the tendency of the subject to occupy its own nest. Gryllacridids were significantly more likely to occupy nests of conspecifics that had been heat-treated than those that were untreated. They were also significantly more likely to occupy heat-treated nests to which acetone extracts from their own nests had been applied than similar nests treated only with solvent. Thus, individuals of Hyalogryllacris sp. 14 are able to relocate their own nests and avoid those of conspecifics based on a chemical cue. This study provides the first evidence of the capacity for individual or self recognition in insects or other invertebrates through a pheromone or any other sensory modality.
Possible effects of kiore (Rattus exulans) on selected indigenous tree species in coastal forests ot northern New Zealand are surveyed from recent field sampling and a literature review Recruitment rates are compared on islands with and without kiore (i) on the same island before or at the time of rat eradication compared with recruitment some years later, and (II) on geographically separated islands with and without kiore In addition kiore‐proof exclosurcs enabled some comparisons to be made of seed germination and survival in the presence and absence of kiore There is evidence that kiore have substantially reduced recruitment of Pittosporum crassifohum, Poutena costata Streblus banksu, and Nestegis apetala by eating the seed Seed consumption and/or depressed recruitment is demonstrated for Rhopalostyhs sapida, Vitex lucens and Pisoma brunoniana, but the extent ot recruitment reduction is not yet clear No depressive effect by kiore on the recruitment ot some species, including Dysoxylum spectabde Beilchmiedia tawa B twain Corvnocarpus laevigatus, Melicytus ramiflorus Pseudopanax arboreus P lessonu and Coprosma macrocarpa, has yet been demonstrated, juveniles remain abundant in the presence of kiore Some tree species most affected by kiore are now rare in coastal forest of the northern islands and mainland Evidence from recruitment reduction in these species suggests that the composition of northern coastal forest before kiore arrived was significantly different from that of the present It also suggests that if rats are present, current successional pathways following burning or other disturbance of coastal forest will not restore the forest to its pre‐human composition
A new species of weta from mainland New Zealand is described and assigned to the previously monotypic genus Motuweta Johns and the genus redefined. Mandibles of adult males bear prominent horns. Motuweta riparia n. sp. is a moderate‐sized species (36 mm) found on the margins of first or second order streams in the eastern mid North Island ranges. Its escape reaction is to leap into the stream and remain underwater until danger has passed, a strategy which has probably enabled it to survive in predator‐infested areas.
The natural formation and maintenance of an aggregation of the endemic New Zealand weta, Hemideina crassidens (Blanchard) is discussed. The mechanics of stridulation are examined and 3 basic patterns of stridulation are recorded with the aid of amplitude-v.-time traces, and the insects' responses are noted.
A programme to improve the conservation status if C. whitakeri is described. The programme involved eradication of introduced Pacific rats Rattus exulans from Korapuki Island (Mercury Islands, N-E New Zealand), documentation of the response of five species of resident lizards to release from the effects of rats, and transfer of 28 Whitaker's kinks from nearby Middle Island. Following removal of rats from Korapuki, resident lizard numbers at some coastal sites increased within 12 months, and rose 20 fold over 5yr, but measurable increases of numbers of lizards in forest areas took up to 6yr. Fifteen of the founding Whitaker's skinks on Korapuki Island have been recaptured 36 times since their release, and five Korapuki-born young have also been caught. The population is now estimated as 33. The increase in number of resident lizards and the success of the introduction of Whitaker's skinks demonstrate that predation rather than habitat deficiencies were responsible for the depleted resident lizard fauna on Korapuki Island. -from Author
We describe the use of harmonic radar in the field with simple, inexpensive tags with extended lifespan. The effects of aerial size and shape, and the detection range of several types of diodes under different conditions are described. Examples are provided of tracking short-term movement of a ground beetle, Plocamosthetus planiusculus, and long-term movement of a snail, Paryphanta busbyi watti. The potential and limitations of the method are discussed
Abstract Advances in determination of conservation status of insects through evaluation of threats (rather than simple ‘rarity’ alone) help to set priorities for allocation of conservation resources, and formulate effective legislative treatment and field management for the most needy species. Summaries of several recent conservation studies on butterflies exemplify the variety of practical needs, amongst which habitat protection and enhancement is paramount. However, the paucity of biological and distributional information on most Australian insects necessitates considerable flexibility in approach, so that perceptions of conservation need may be highly subjective. Listing species for protection and conservation priority must be viewed as a dynamic process, with opportunity for rapid action, either to list or de-list taxa as research and recovery actions lead to change in perceived or real status and conservation need.
Juvenile gryllacridid Orthoptera, known as raspy crickets, build nests or burrows as soon as they hatch. Both juveniles and adults are central place foragers that search for food at night and return to the same nest each morning. This study examines the homing abilities of juveniles of an undescribed species of gryllacridid from Western Australia. Juveniles were placed in a simple maze, which consisted of two chambers, one containing the nest and the other empty, linked by wide glass tubes to a central chamber containing food. The food was placed in this chamber with a consistent orientation relative to the exit tubes leading to the nest and empty chambers. Juveniles appeared to learn which chamber contained their nest and thereafter ignored the route towards the empty chamber. By exchanging the connecting glass tubes, it could be established that juvenile crickets were not using chemical trails to find their home. The positions of the empty and nest chambers with respect to the central chamber were exchanged and, in a separate manipulation, the spatial configuration of the food in the central chamber was also changed. Both manipulations resulted in a decrease in successful returns to the nest chamber, the former because the nest had been relocated, the latter presumably because the spatial arrangement of items within the food chamber now presented orientation cues, which led to the empty chamber. Furthermore, juveniles were able to estimate distance travelled, despite the absence of chemical or visual cues. Juvenile raspy crickets appear to be able to maintain nest fidelity from a very early age by using spatial landmarks and appear capable of measuring translational displacement intrinsically.
Cockroaches use navigational cues to elaborate their return path to the shelter. Our experiments investigated how individuals weighted information to choose where to search for the shelter in situations where path integration, visual and olfactory cues were conflicting. We showed that homing relied on a complex set of environmental stimuli, each playing a particular part. Path integration cues give cockroaches an estimation of the position of their goal, visual landmarks guide them to that position from a distance, while olfactory cues indicate the end of the path. Cockroaches gave the greatest importance to the first cues they encountered along their return path. Nevertheless, visual cues placed beyond aggregation pheromone deposits reduced their arrest efficiency and induced search in the area near the visual cues.
Experiences from the first efforts to translocate an orthopteran, the Mahoenui giant weta (Deinacrida sp.), are described. Some of the problems included monitoring at low densities, transferred weta dispersing and coordinating the different components of the translocation programme over a long period of time. Options for translocation are discussed, such as using wild-caught or captive-bred animals. Techniques of release, such as immediate release or using an enclosure on the release site, allowing transferees to breed, then releasing their progeny, are also discussed. It was concluded that the latter was probably the most effective approach to translocation.
Homing ability of the cricket Gryllus campestriswas experimentally studied in the field after passive and active displacements. Whatever the weather conditions and the nature of the displacement, crickets (18/18) home directly when they are located between 5 and 15 cm from their burrow by performing real-time orientation. When moved by the experimenter between 15 and 55 cm away from home, some crickets (26/43) can retrieve their burrow by systematic searching only after winding inward trips but they get lost (0/18) beyond 55 cm. After self-generated movements between 5 and 85 cm away from home, crickets (33/35) return to their burrow under blue sky, but they cannot home as well under overcast sky (22/34 from 5 to 65 cm and 0/5 beyond). The volatile memory orientation system allowing path integration is based on the polarized skylight of the sun.
When monitoring rare insect species, or when surveying faunas within nature reserves, it is desirable not to use indiscriminate
lethal sampling techniques. In this investigation we assessed the usefulness of simple tree-mounted wooden shelters to monitor
endemic weta (Orthoptera) in nature reserves in Canterbury, New Zealand. Fifty shelters were placed out at six sites and examined
at three-monthly intervals for a year. A wide variety of invertebrates were found utilizing the shelters, with Arachnida,
Blattodea and Collembola being the most common occupants. After three months over 80% of the shelters exhibited signs of use
by invertebrates, increasing to 96% after 12months. Only seven tree weta (Anostostomatidae) and one (dead) ground weta (Hemiandrus sp.) were observed in the shelters over the full 12month period. There were 52 observations of cave weta (Rhaphidophoridae)
in the shelters, 36 of which occurred at one site, Orton Bradley Park. Occupation of the shelters by cave weta was not affected
by soil conditions, light intensity or aspect of the shelter. However, cave weta exhibited a preference for shelters less
than 50cm above the ground and for shelters attached to kanuka and vines. Although weta were found in only a small proportion
(9%) of the shelters, this method proved useful in confirming the presence of weta without risk of harming vulnerable populations.
These shelters are inexpensive and easy to manufacture and have potential for long-term non-lethal monitoring of weta and
as a collection/carriage device for live specimens used in conservation translocations.
We reviewed 180 case studies and a number of theoretical papers on animal relocations published in 12 major international scientific journals over the last 20 years. The study focused on re-introductions, supplementations and translocations (sensu IUCN, 1996. IUCN/SSC Guidelines for Re-introductions. 41st Meeting of the IUCN Council, Gland, Switzerland, May 1995. Http://iucn.org/themes/ssc/pubs/policy/hinte.htm.). We did not assess introductions. Re-introductions were the most common type of relocation (116/180); three quarters of these were conducted for conservation purposes. Supplementations (48/180) and translocations (36/180) occurred less frequently, and both were commonly carried out for reasons other than conservation. Simple descriptive statistics were used to analyse factors influencing relocation success. Translocations that aimed to solve human–animal conflicts generally failed. Re-introduction success was not found to have changed over the last two decades, but re-introductions appeared to be more successful when the source population was wild, a large number of animals was released (n>100), and the cause of original decline was removed. More complex trends were found for the effect of predation and the use of supportive measures such as provision of food or shelter, or predator control prior to release. The success of 47% of re-introductions was uncertain at the time case studies were published in journals. This was partly due to the lack of generally accepted and widely applied criteria to assess success. Very few case studies (3%) reported the cost of the relocation attempt. We conclude that there were three primary aims for animal relocations. These were to solve human–animal conflicts, to restock game populations, and conservation. Our extensive review of the present literature leads us to conclude that the value of animal relocations as a conservation tool could be enhanced through (1) more rigorous testing for the appropriateness of the approach in a given case, (2) the establishment of widely used and generally accepted criteria for judging the success or failure of relocations, (3) better monitoring after a relocation, (4) better financial accountability, and (5) greater effort to publish the results of relocations, even ones that are unsuccessful.
Invertebrates are attracting increasing interest within the veterinary profession. They are also significant in their own right; as the Council of Europe's "Charter on Invertebrates" points out, they are the most important component of wild fauna as well as providing food, contributing to agriculture and forestry, and aiding medicine,industry, and crafts. Whenever invertebrates are kept in captivity they should be subject to high standards of management and care and veterinary attention-whether by the veterinarian or by the veterinary technician-should be based on sound biological and humanitarian principles.
The potential for ecological restoration in the Mercury Islands Ecological restoration of New Zealand Islands
- Dr Towns
- Atkinson
- Daugherty
- Towns Dr
- Daugherty
- Atkinson