Suchergebnisse

Of the extant species of land mammals, 124 (2.6%) can be classed as 'successful invaders', whereas 1038 (21.6%) are classed as threatened, according to the 2006 IUCN Red List. Relatively high proportions of successful invaders are found among Artiodactyla, Carnivora, Lagomorpha and Perissodactyla. Compared with other organisms, mammals seem relatively likely to become established when introduced outside their natural range. Studies of determinants of invasion success indicate that the number of individuals released, the size of the natural range of the introduced species, and the temperateness of climate in the new range can all increase the probability of establishment of introduced mammals. Negative impacts of invasive mammals on native biodiversity include direct effects such as predation, browsing and competition, but can extend to disruption of patterns of nutrient flow, and trophic cascades. Eradication of several species of invasive mammals from increasingly large areas is now possible. In this context, it is important to better understand ecological interactions between such mammals (and between them and other species) to avoid unwanted consequences such as mesopredator or competitor release, after the removal of particular species. Finally, it is increasingly apparent that research is needed on the behaviour of dispersing and invading individuals, to improve the early detection of new mammal invasions or reinvasions.

Abstract
ContextPest species are a widespread environmental and biodiversity threat and understanding people's attitudes towards managing pests is critical for nature conservation. Attitudes towards pest species and their management are often contextually dependent on the species and location, and no domain-free measure is currently available. This prevents straightforward comparisons of studies and generalisation of attitudes towards pest species globally.
AimUndertake initial psychometric tests of a unidimensional pest-management attitude (PMA) scale in three community samples from the two largest cities of New Zealand. The PMA scale comprises statements intentionally absent of specific reference to pest species or pest-management methods, and avoids terminology that has the potential to become outdated, as a result of evolving management methods and technology or the emergence of new pests. This broad focus aims to enable the ongoing use of the scale, within differing geographical contexts.
MethodTwo studies tested the psychometric properties of the PMA scale. Tests comprise assessing the scales dimensionality through exploratory and confirmatory factor analysis, and measurement equivalence across samples. Internal consistency was tested through Cronbach's α, and demographic and context-specific measures were used to validate the scale using correlation measures.
ResultsExploratory and confirmatory factor analyses confirmed the nine-item, one-factor model of the PMA scale in Study 1 (n=1190). Measurement and structural invariance of the one-factor model was confirmed across two distinct samples in Study 2 (n=739 and 705). Internal consistency (Cronbach's alphas=0.73 to 0.81) and criterion-related validity of the PMA scale was supported in both studies, with greater PMA scores being associated with membership of a conservation or environmental organisation, active participation in conservation over the past 12 months, active actions for pest control, and not owning a pet.
ConclusionsResults demonstrated high construct and criterion validity of the PMA scale, which might have powerful global utility as a context-independent measure of attitudes to pest species and their management.
ImplicationsThrough generalising the social components of pest management, regardless of target species or method, there is potential to unify global studies in pest management.

Context Long-term monitoring is essential for control and eradication of invasive mammalian predators. Relative abundance indices are increasingly used when assessing population changes. However, indexing assumes constant detectability, when, in fact, it varies depending on numerous factors, including the type and spacing of monitoring devices, seasons, vegetation types, and inter- and intra-specific interactions. Aims We studied a population of Pacific rat (Rattus exulans) and examined the influence of vegetation types, seasons and inter-specific interactions on their detection. Methods We deployed tracking-tunnels, live-traps, chew cards, and trail cameras in three vegetation types during summer and winter. Detection rates of Pacific rats, mice (Mus musculus), stoats (Mustela erminea) and weka (Gallirallus australis) were calculated and compared among vegetation types, seasons and devices. Key results Pacific rats were not detected by any monitoring devices in the farmland, despite their presence in this habitat. In the forest and shrubland, cameras had the highest detection rate among all of the monitoring devices, whereas live-trap and chew cards failed to detect rats. Tracking tunnels detected Pacific rats only in the shrubland. Camera detections of Pacific rats were lower in winter than in summer, and detections were dominated by weka and stoats for both seasons. The seasonal effects may have reflected the population cycle of Pacific rats. Weka and stoats caused substantial physical interference to the tracking tunnels, live-traps and chew cards, which is likely to have deterred Pacific rat interactions through imposing high predation risks. Conclusions Cameras were the most effective device at detecting Pacific rats in low density and under high predator disturbances. Tracking tunnels and chew cards that are successful at detecting other Rattus spp. might not be reliable for detecting Pacific rats. Implications We recommend using camera monitoring for rodents where population density is low, or predator disturbance is high, and species are identifiable from pictures. Studies that draw inferences from relative abundance indices on rodents should exercise caution when rodent detectability is unknown.

Context Mangroves and intertidal habitats have been identified as particularly challenging environments for bait application within both tropical and temperate environments, because bait applied to areas that are tidally inundated could degrade rapidly or become inaccessible to rats. Aims To determine rat density, ranging behaviour and probability of detection using different monitoring devices; additionally, to determine the availability (persistence, durability and uptake) of rodenticide baits within tidally inundated mangrove habitats. Methods The population biology of black rats (Rattus rattus) was studied in two contrasting mangrove habitats on Europa Island, and spatially explicit mark–recapture studies were performed to estimate densities and activity of rats. A series of bait availability trials was conducted to determine the durability of rodenticide baits on the ground and uptake in the canopy ('bait bolas'). Key results Black rats were found to be abundant in mangrove, and despite daily tidal inundation, still maintained ranging behaviour consistent with rats in adjacent terrestrial habitats. Larger rodenticide bait blocks remained within tidally inundated habitat throughout tidal cycles and were available and remained palatable to rats for at least three consecutive nights, although strong bait competition occurred with crabs. Bait bolas were available in mangrove canopy exclusively to rats and consumption commenced on the first night. Conclusions The results provide evidence that mangrove habitats are an important habitat for rats, but the biology of rats in these habitats does not meaningfully differ from adjacent terrestrial habitats. With the use of larger rodenticide blocks, tidal inundation does not affect bait availability, but crabs remain a major competitor for these baits. Alternatively, the present study revealed that bait bolas limit bait access to rats alone. Development as an aerial eradication technology should be also recommended. Implications These results provide a proof of concept that eradication of rats from tidally inundated habitats such as mangrove should be possible with only small modifications to current best practice.

Abstract
ContextEradication of invasive species is necessary to protect and assist the recovery of native species and ecosystems. Knowing when to declare an eradication has been successful after ongoing non-detections is a challenge.
AimsThe rapid eradication assessment (REA) model is a powerful simulation framework to determine, given model parameters and a fixed level of monitoring effort, the level of confidence in declaring the success of pest eradication. The aim of the present study was to extend the current functionality of the REA model for broader applicability.
MethodsThe REA model was advanced so that it was able to account for (1) usage of multiple static device types with different probabilities of detection, (2) incursion detection at a known location and (3) usage of mobile detection devices, which are increasingly being used in conservation.
Key resultsAn invasive rat incursion response on Great Mercury Island in New Zealand is used as a comprehensive example to demonstrate the distribution of estimated probability of pest absence among the cases using the current REA model and the extensions presented here.
ConclusionsAlthough Great Mercury Island already had a sparse but extensive island-wide network of static biosecurity surveillance devices, and deployed additional static devices around the area of incursion, the greatest improvement in the estimated probability of pest absence following a rat incursion was from additionally using a trained rodent-detection dog.
ImplicationsThe added functionality in the REA model and demonstration of its use on a real-world scenario will allow more realistic application by wildlife managers.

Context
Dogs are often used to find rare or cryptic species, but search methods are not standardised, making it difficult to interpret and compare results. Standardised approaches are needed to optimise search effectiveness and/or efficiency. Designing an optimal search strategy requires knowledge of the effective sweep width, which is related to the probability of detection (POD) at various distances between the searcher and the search object.

Aims
Our primary aim was to estimate effective sweep width for wildlife-detector dogs searching for rodents. We also tested whether dogs differed in their reaction on encountering a laboratory rat (Rattus norvegicus) or a wild-caught Norway rat (wild-type R. norvegicus).

Methods
We conducted field trials using trained rodent-detector dogs to locate dead laboratory rats. We used the numbers of detections and non-detections at distances of 0–100 m to estimate detection probability and effective sweep width.

Key results
Dog teams located 100% of rats (regardless of strain) placed directly in their search path. POD declined rapidly with an increasing distance, yielding an observed detection rate of 33% at 10 m, and close to zero at ≥20 m. The data were best described by an exponential decay function. Effective sweep width was estimated to be 16.8 m (95% confidence interval 12.3–21.4 m), corresponding to a strip extending 8.4 m on either side of a walked track. Handlers could not consistently judge whether a dog had encountered a laboratory rat or a wild rat.

Conclusions
Our results suggest that when dogs are >10 m from a source of rat odour, POD declines sharply. We estimate that the effective distance explored when searching for a stationary rodent is 8.4 m either side of the search path.

Implications
This information will allow users to optimise the search pattern that dog teams should follow for a given search scenario.

Acknowledgements Thanks to the Tetiaroa Society and The Brando resort for facilitating research on Tetiaroa atoll for the past decade, especially Neil Davies, Frank Murphy, Nicolas Leclerc and Moana Le Rohellec. Funding Open Access funding enabled and organized by CAUL and its institutions. FGA was funded by Brazilian Ministry of Science and Technology CAPES (Grant No. 88881.189218/2018-01), FP was funded by NZ BioHeritage National Science Challenge (Grant No. 1617-44-033), TWB was funded by European Union's Horizon 2020 research and innovation programme Marie Skłodowska-Curie fellowship (Grant No. 747120), AS was funded by Island Conservation and RSPB, JCR was funded by FRST NZ S&T postdoctoral fellowship (Grant No. UCAL 0801). ; Peer reviewed ; Publisher PDF

For assistance collecting samples in the field the authors thank David Thompson, Erica Sommer, David Boyle and Mark Fraser in summer 2011, Helen Nathan, Terry Greene and Graeme Elliott in winter 2013, Fin Cox in autumn 2016 and Jose Luis Herrera in winter 2016. Thanks to the Department of Conservation, Murihiku, for logistical support, and Hank Haazen and crew of the Tiama for transport. Funding was provided for the summer 2011 expedition by NIWA and winter 2013 expedition by the National Geographic Society (Grant No. 9322-13). Thanks to Stephen Thorpe, Robert Hoare, and John Marris for taxonomic identification of invertebrate samples. Thanks to Surrya Khanam for laboratory sorting, Julie Brown and Anna Kilimnik for stable isotope laboratory analyses and Wendy Nelson for macroalgae identification. JCR is currently funded by the Royal Society of New Zealand Rutherford Discovery Fellowship (Grant No. RDF-UOA1404). TWB is currently funded by the European Union's Horizon 2020 research and innovation programme Marie Skłodowska-Curie Fellowship (Grant No. 747120). Thanks to Katherine Russell and two anonymous reviewers for feedback on the manuscript. This research was conducted under DOC entry (SO-29716-LND 1011/35) and research (SO-29140-FAU 1011/20) permits, and University of Auckland Animal Ethics Committee approval (R845). ; Peer reviewed ; Publisher PDF

Rats continue to invade rat-free islands around the world, and it remains difficult to successfully intercept them before they establish populations. Successful biosecurity methods should intercept rats rapidly, before they can establish a population. Current island biosecurity practice employs techniques used for high-density rat eradication, assuming that they will be equally effective on low-density invaders. However, such approaches are often untested. Adult male Norway rats (Rattus norvegicus) were individually released onto forested rat-free islands in New Zealand to test methods of detecting and eliminating a single invader. Only half the rats released were caught within a two-week timeframe, although the mean time to interception was just under 14 days. Permanent island biosecurity surveillance systems performed better than contingency responses. Success rates were higher on islands where complete coverage could be obtained, although surveillance systems using multiple devices eventually detected most invading rats. For some rats a change of methods was necessary. Single invading rats left a rat-free island despite the presence of excessive natural food resources. With surveillance systems comprising an array of tested island biosecurity devices, and where necessary a contingency response using alternative methods, it should be possible to maintain islands as rat-free even when they have a high reinvasion rate.

Acknowledgments Funding for sample collection was provided by the Shackleton Scholarship Fund, Antarctic Research Trust, the Wyoming Biodiversity Institute, PVE/CAPES (Proposal 235453) and Fundação para a Ciência e a Tecnologia (SFRH/BPD/88854/2012). Thanks to Martin Collins, Andy Black, Darren Christie and the Government of South Georgia and South Sandwich Islands for the provision of samples from South Georgia, Annalea Beard for providing the rat sample from St Helena Island, Joaquim Tapisso, Rita Monarca and Ana Cerveira for samples from Portugal, and Emily Puckett for help validating South American SNP haplotypes. Funding for DNA sequencing was provided by Island LandCare, the University of Auckland. Thanks to two anonymous reviewers for the constructive comments. ; Peer reviewed ; Publisher PDF

Este artículo contiene 27 páginas, 2 tablas, 5 figuras. ; Shearwaters and petrels (hereafter petrels) are highly adapted seabirds that occur across all the world's oceans. Petrels are a threatened seabird group comprising 124 species. They have bet-hedging life histories typified by extended chick rearing periods, low fecundity, high adult survival, strong philopatry, monogamy and long-term mate fidelity and are thus vulnerable to change. Anthropogenic alterations on land and at sea have led to a poor conservation status of many petrels with 52 (42%) threatened species based on IUCN criteria and 65 (52%) suffering population declines. Some species are well-studied, even being used as bioindicators of ocean health, yet for others there are major knowledge gaps regarding their breeding grounds, migratory areas or other key aspects of their biology and ecology. We assembled 38 petrel conservation researchers to summarize information regarding the most important threats according to the IUCN Red List of threatened species to identify knowledge gaps that must be filled to improve conservation and management of petrels. We highlight research advances on the main threats for petrels (invasive species at breeding grounds, bycatch, overfishing, light pollution, climate change, and pollution). We propose an ambitious goal to reverse at least some of these six main threats, through active efforts such as restoring island habitats (e.g., invasive species removal, control and prevention), improving policies and regulations at global and regional levels, and engaging local communities in conservation efforts. ; AR and FR were supported by Juan de la Cierva programme, Spanish Ministry of Economy, Industry and Competitiveness (IJCI-2015-23913 and IJCI-2015-24531). ML was funded by the Ramón y Cajal programme (RYC-2012-09897), Spanish Ministry of Economy, Industry and Competitiveness. WM was supported by an NSERC Discovery grant. MG was partially supported by the European Union (MINOUW Project, H2020-634495). JMA and VC were supported by ZEPAMED Project, Pleamar programme, Fundación Biodiversidad, Spanish Ministry of Ecological Transition. ; Peer reviewed