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The freshwater snail Latia neritoides occurs in certain streams and lakes of New Zealand's North Island. It defends itself against predators with a unique mechanism - the release of sticky, glowing mucus. Two possible origins of this defence mucus had earlier been suggested: the foot and the pneumostome area. After examining the glandular system of the foot in a previous study, in the present study we examined the general morphology of L. neritoides, focusing on the mantle cavity. With the first complete 3D model of L. neritoides now available, it is possible to evaluate previous morphological studies and to give non-specialists a better understanding of the soft part anatomy of this fascinating gastropod. As a by-product of this, we also compared the capabilities of μ-CT and HREM on a methodological level. We characterized the two most common gland types in the mantel cavity (Lmcg1/Lmcg2) on the basis of their ultrastructure. They are present in large numbers and, therefore, regarded as likely candidates for being the producers of one or more components of the defence mucus. This notion was confirmed by histochemical analyses of Lmcg1 and Lmcg2 and other gland types in L. neritoides. [ABSTRACT FROM AUTHOR]

The assessment of site suitability is a crucial step for informing future successful species reintroductions. It ensures that translocated species have the highest chance of survival in their new environment while minimising ecological risks. However, it can be challenging when risk factors are unknown, especially when working with sessile species that cannot easily relocate to more favourable conditions. Under these scenarios, rapid (1-2 week-long), small-scale (< 1 m²) experimental translocations can help reduce uncertainty and improve restoration outcomes. This study conducted small-scale experimental translocations of green-lipped mussels, Perna canaliculus, to 11 shallow coastal sites spread across Tık? apa Moana/the Hauraki Gulf, Aotearoa/New Zealand to investigate the relationship between predator abundance, environmental factors, and mussel loss to help refine existing site selection criteria. The total number of known mussel predators counted from timelapse images was used as a proxy for potential predator pressure. Translocated mussel survival ranged from 10 - 99% and was best predicted by current speed, wind direction, predator abundance, water clarity, and depth (adjusted R² = 0.505). Predator abundance was best explained by site location (p = 0.001) and had weak correlations among environmental parameters (Rho = 0.067). These results suggest that small, short-term (1-2 week) experimental translocations can help to refine site selection criteria and reduce uncertainty in the site-selection process for larger-scale shellfish reintroduction efforts with unknown and/or hard-tocontrol risk factors. [ABSTRACT FROM AUTHOR]

Predator Free 2050 (PF2050) is a government initiative aiming to eradicate selected invasive mammals (mustelids, rats, and possums) from New Zealand (NZ) by 2050. Selecting which of 32 introduced mammal species to include has received little evaluation, yet targeting a few species often results in perverse ecological outcomes given interactions within the invasive guild. We explore how PF2050 could be improved strategically by focusing on biodiversity outcomes instead of selectively targeting invasives, using rodents as an example. Current PF2050 targets include all rat species (Rattus exulans, R. norvegicus, and R. rattus), but not the house mouse (Mus musculus). Mice can be as damaging as rats when competition and predation are removed, negating benefits of rat removal. Multirodent eradications are more cost‐effective and prevent mesopredator release. Using a case study, we show adding mice to a rat eradication would raise costs modestly, comparing favorably to independent mouse eradication later, which would be riskier and more socially and economically costly than the preceding rat eradication. Missing the opportunity to tackle all rodents simultaneously, leaving mice to multiply in numbers and impacts, could have serious environmental and socioeconomic consequences. Naïve eradication strategies neglecting ecological expertise risk biodiversity outcomes and NZ's eradication science reputation. [ABSTRACT FROM AUTHOR]

This review covers the volatile organic compounds (VOCs) emitted by the bodies and secretions of introduced mammalian predators in New Zealand forests, with a specific focus on mice, rats, ferrets, stoats, and possums. The primary aim is to compile information on these VOCs and assess the potential of exploiting these VOCs as unique biomarkers for predator detection in the forest. While a universal VOC has yet to be identified, the review discusses various VOCs associated with predators and their potential as unique biomarkers for detecting the presence of predators, including 2-heptanone, 4-heptanone, 2-octanone, and benzaldehyde. Furthermore, a brief overview of different VOC detection techniques is provided, connecting the selection of biosensing techniques with the detection of volatile biomarkers. Further research and advancement in the biosensing field hold substantial potential to enhance biomarker detection technologies and elevate predator management strategies within New Zealand forests. [ABSTRACT FROM AUTHOR]

Invasive species pose a threat to biodiversity, and as such feature in some conservation education programs. However, there is debate about how to teach this difficult subject. We explored perspectives using a case study of education about introduced mammalian predators in Aotearoa New Zealand (NZ). We conducted semi-structured interviews with 18 NZ educators and animal welfare advocates and supplemented these data with material from a broader project on predator control in NZ. Our data indicated agreement that education should: 1) encourage respect for all animals, i.e., introduced predators should not be demonized and must be killed humanely; 2) enable children to develop their own opinions, e.g., whether to participate in trapping; and 3) designing programs to suit specific contexts, e.g., rural versus urban. However, there were disagreements, for example at what age children might begin trapping, and whether guiding students toward a particular conclusion is compatible with enabling their agency. [ABSTRACT FROM AUTHOR]

Spatio-temporal models are widely applied to standardise research survey data and are increasingly used to generate density maps and indices from other data sources. We developed a spatio-temporal modelling framework that integrates research survey data (treated as a "reference dataset") and other data sources ("non-reference datasets") while estimating spatially varying catchability for the non-reference datasets. We demonstrated it using two case studies. The first involved bottom trawl survey and observer data for spiny dogfish (Squalus acanthias) on the Chatham Rise, New Zealand. The second involved cod predators as samplers of juvenile snow crab (Chionoecetes opilio) abundance, integrated with industry-cooperative surveys and a bottom trawl research survey in the eastern Bering Sea. Our integrated models leveraged the strengths of individual data sources (the quality of the reference dataset and the quantity of non-reference data), while downweighting the influence of the non-reference datasets via the estimated spatially varying catchabilities. They allowed for the generation of annual density maps for a longer time-period and for the provision of one single index rather than multiple indices each covering a shorter time-period. [ABSTRACT FROM AUTHOR]

Cats are known predators of bats, but there are few published accounts of predation attempts. In this paper we report on two recent examples of bats being attacked by cats (Felis catus) in New Zealand. We found a Central lesser short-tailed bat (Mystacina tuberculata rhyacobia) in the gastrointestinal tract of a feral cat that was trapped in indigenous forest. We also report on a case where seven long-tailed bats (Chalinolobus tuberculatus) were killed or injured over two years by a companion cat living in a rural landscape. We confirmed cat attack/predation using diet analyses, and pathological assessment and identification of the predator using DNA. We consider that depredation of bats by feral, stray, and companion cats is likely to be substantial and occur within all habitats where bats and cats overlap. LSID: urn:lsid:zoobank.org:pub:8933333F-D145-41CF-BA20-3AE73D3B86B4 [ABSTRACT FROM AUTHOR]

This study explored the communication of Predator Free 2050 (PF2050), a biodiversity conservation programme promoted by the New Zealand government. Drawing on semi-structured interviews and an online survey, the study found that the information about PF2050 was made available by diverse contributing agencies but ineffectively disseminated to the public who believed PF2050 provided insufficient or unclear communication. These were experienced as barriers to public engagement with PF2050. A coordinated approach is judged vital to communicate PF2050 to the public. A key to this coordination is effective engagement with Māori as Treaty partners to ensure the success of PF2050. This study provides valuable insights into the features provoking and sustaining public engagement with biodiversity preservation in Aotearoa New Zealand and highlights the need for environmental movements worldwide to improve communication publicity and visibility. It contributes to our understanding of prioritising both inclusiveness and cultural sensitivity if communication strategies are to inspire collaborative actions of the public. [ABSTRACT FROM AUTHOR]

Historical resurveys of ecological communities are important for placing the structure of modern ecosystems in context. Rarely, however, are snapshot surveys alone sufficient for providing direct insight into the rates of the ecological processes underlying community functioning, either now or in the past. In this study, I used a statistically reasoned observational approach to estimate the feeding rates of a New Zealand intertidal predator, Haustrum haustorium, using diet surveys performed at several sites by Robert Paine in 1968–1969 and by me in 2004. Comparisons between time periods reveal a remarkable consistency in the predator's prey‐specific feeding rates, which contrasts with the changes I observed in prey abundances, the predator's body‐size distribution, and the prey's proportional contributions to the predator's apparent diet. Although these and additional changes in the predator's per‐capita attack rates seem to show adaptive changes in its prey preferences, they do not. Rather, feeding‐rate stability is an inherently statistical consequence of the predator's high among‐prey variation in handling times which determine the length of time that feeding events will remain detectable to observers performing diet surveys. Though understudied, similarly high among‐prey variation in handling (or digestion) times is evident in many predator species throughout the animal kingdom. The resultant disconnect between a predator's apparent diet and its actual feeding rates suggests that much of the temporal, biogeographic, and seemingly context‐dependent variation that is often perceived in community structure, predator diets, and food‐web topology may be of less functional consequence than assumed. Qualitative changes in ecological pattern need not represent qualitative changes in ecological process. [ABSTRACT FROM AUTHOR]

Structured habitats play an important nursery role during the crucial early juvenile or post‐settlement stages of many fish species. Predominantly, the utility of structured habitats to juvenile fish is thought to be associated with the provisioning of food or as a refuge from predation. Although snapper (Chrysophrys auratus) in New Zealand also have a strong affinity for structured habitats during their post‐settlement phase, their predators are unknown as is the role of predation in determining habitat association. Here the authors investigated potential predators of post‐settlement snapper by remotely observing interactions of restrained post‐settlement snapper with potential predators and investigating the diet of potential predators. They also conducted tank experiments with a potential predator, both with and without the presence of structure. Restrained snapper were infrequently approached by predators, but two new nocturnal predators were identified. No snapper were observed in the diet of potential predators, although two piscivores were identified as potential candidates. No predation occurred during tank experiments, but there was a non‐significant indication that under threat of predation post‐settlement snapper may use habitat when it is present and aggregate together when it is not. The findings suggest that the pulsed nature of predation may have made it difficult to observe given the methods employed and that the threat of predation may be sufficient to drive the habitat selection of post‐settlement snapper. Investigating the significance of predation via methods that do not require direct observations may therefore be more appropriate given this context. [ABSTRACT FROM AUTHOR]

Simple Summary: Restoration of biodiversity in urban green spaces frequently requires eradication or management of invasive species. We aimed to identify fine- and landscape-scale habitat features associated with the presence of five invasive urban mammals (Rattus species, European hedgehogs, mice, and brushtail possums) in three urban green space types (forest fragment, amenity park, residential garden) across three New Zealand cities, and across two seasons, to identify where management effort should be focused. All species were detected in all greenspace types; however, rodents were detected least in residential gardens, possums were detected most often in forest fragments, and hedgehogs least in forest fragments. Proximity of amenity parks to forest patches was positively associated with possum and hedgehog presence and negatively with rats. Conversely, proximity of residential gardens to forest patches was positively associated with rat presence. Management of rats should focus on sites with shrub and lower canopy cover and of mice on sites with herb layer cover, while micro-habitat features were not important for hedgehogs and possums. Rats were most likely to be found in residential gardens with compost heaps. The wide distributions of these species suggest that in order to be successful, ecological restoration must be coordinated, target all green space types, and engage urban residents. A barrier to successful ecological restoration of urban green spaces in many cities is invasive mammalian predators. We determined the fine- and landscape-scale habitat characteristics associated with the presence of five urban predators (black and brown rats, European hedgehogs, house mice, and brushtail possums) in three New Zealand cities, in spring and autumn, in three green space types: forest fragments, amenity parks, and residential gardens. Season contributed to variations in detections for all five taxa. Rodents were detected least in residential gardens; mice were detected more often in amenity parks. Hedgehogs were detected least in forest fragments. Possums were detected most often in forest fragments and least often in residential gardens. Some of this variation was explained by our models. Proximity of amenity parks to forest patches was strongly associated with presence of possums (positively), hedgehogs (positively), and rats (negatively). Conversely, proximity of residential gardens to forest patches was positively associated with rat presence. Rats were associated with shrub and lower canopy cover and mice with herb layer cover. In residential gardens, rat detection was associated with compost heaps. Successful restoration of biodiversity in these cities needs extensive, coordinated predator control programmes that engage urban residents. [ABSTRACT FROM AUTHOR]

Live trapping (e.g. pitfall trapping or funnel trapping) is an important sampling tool for a wide range of small terrestrial animals and is one of the predominant methods for survey and monitoring of terrestrial lizards in New Zealand. As it results in the confinement of animals, methods using live trapping must mitigate risks to animal welfare. Foraging predators can kill or injure animals confined in pitfall traps (e.g. lizards); however, visitation rates of various predatory mammals are poorly understood and reported occurrences are largely anecdotal. Following an observation of a rat depredating a skink in a pitfall trap during a lizard salvage operation, we recorded the removal of bait (pear) from traps over a 24-h period and installed motion-detecting cameras to record trap visitation. Bait loss occurred rapidly over the observed period, with 77% removed after 24 h. Three rodent species were detected visiting a trap, with one ship rat (Rattus rattus) entering it and removing the bait. We suggest that operations involving live trapping of lizards should consider predator densities and carefully monitor and report trap disturbance. Further research should examine how different trapping methods (e.g. predator-exclusive trap design, baiting, and timing of trap checks) might reduce the risk of predation to trapped animals. [ABSTRACT FROM AUTHOR]

The introduction of mammalian predators often results in loss of native biodiversity due to naiveté of native prey to novel predators. In New Zealand, an island system with virtually no native mammalian predators, introduced mammalian predators threaten a large proportion of the native fauna. A critical step in adapting to introduced predators is the ability to recognize and respond to a novel predation threat. Whether New Zealand's lizards can do this has received little attention. We compared the basking behaviour of native McCann's skinks (Oligosoma maccanni) when exposed to a live cat (Felis catus), cat body odour, a model raptor (representing a coevolved predator) or procedural controls. We inferred predator recognition from reductions in individual basking and higher selection for basking sites with greater refuge availability. We tested these behavioural responses for two skink populations: one from an area with high abundance of mammalian predators including feral cats and the other from a fenced conservation reserve where predators have been excluded for over 10 years (3–4 skink generations). Skinks from the high‐predator population reduced basking when exposed to cat and raptor cues, whereas skinks from the predator‐free population did not. These results suggest that within approximately 150 years of exposure to novel predators, McCann's skinks might be able to recognize the threat posed by invasive mammals. However, they also demonstrate that predator recognition and antipredator behaviours may not necessarily be retained once gained. The rapid loss of basking‐related antipredator behaviours might reflect the high fitness costs of reduced basking for this species. Our results indicate that the behavioural response of skinks is flexible and that skinks may maximize individual fitness by balancing the risk of predation with the costs of antipredator behaviours. [ABSTRACT FROM AUTHOR]

Mammalian predators are threatening New Zealand's endemic species with extinction. Community-led predator control may contribute to a predator-free nation by 2050. An individual's present and future thoughts about, and subsequent actions for, conservation rely on their current and projected motivations and concerns. Innovative approaches to conservation action theme elicitation and analysis were developed through this visual arts based qualitative study to better understand how people feel about the present and future and their place within. Twenty-five males and females from New Zealand's rural and urban communities, aged between 12 and 75 years, from primary, secondary and tertiary student, environmental education and community conservation backgrounds, each created two collages of themselves situated in today's and a future world. Interviewer-led open-ended laddering questions elicited participant responses to their collages. A further open-ended question elicited actions participants would take to move from their perceived present to a projected future world. Trello, a web-based list-making application, facilitated reflexive thematic analysis of the interview transcripts. The following six common themes resulted: connectivity, commitment, learning cycle, practical actions, unconditional belief and group action. These themes, presented as eight-point Likert-type scale items in a Qualtrics digital survey, contributed to the quantitative aspect of this mixed-methods study and may facilitate understanding of future New Zealand volunteer community conservation participation. [ABSTRACT FROM AUTHOR]

Urbanisation and anthropogenic alteration of ecosystems has led to conflict between humans and wildlife. Such conflict is often observed in apex predators. Although human–wildlife conflict has been extensively studied, male/female differences in behaviour are rarely considered.We investigated male/female differences in foraging behaviour of the predatory/scavenging brown skua Catharacta antarctica lonnbergi breeding on a New Zealand island nature reserve in proximity to farmland. These skuas are subject to culling, when perceived as a threat to livestock.As part of a long‐term ecological study, we used high‐resolution Global Positioning System (GPS) devices to characterise the space‐use of foraging brown skuas. We also analysed stable isotopes of carbon (δ13C) and nitrogen (δ15N) from modern and archived blood samples to investigate possible changes in diet over the past ~30 years.Analysis of 100 GPS tracks collected from 2014 to 2016 demonstrated that males and females consistently visited different habitats. Males spent most of their time close to their breeding territory on the island nature reserve and females frequently visited a farmed island approximately two kilometres away. Consistent with this finding, we show that male and female skuas also differed markedly in their diets: males specialised on burrow‐nesting white‐faced storm petrels Pelagodroma marina (80%) with only a small proportion of sheep remains Ovis aries (<6%) contributing to their diet. In contrast, female diet comprised 27% white‐faced storm petrels, other seabirds (18%) and a relatively large proportion of sheep remains (47%). Further, our data (186 blood samples from 122 individuals) show that this male/female difference in diet has persisted at least since 1987.Because females fed disproportionally on sheep remains, they may be more vulnerable to being culled by farmers. Importantly, our case study suggests that intersexual differences in diet and foraging patterns can have major implications for the reproduction and survival of apex predators that interact with farming. We strongly suggest that intersexual differences in behaviour should be considered when investigating human–wildlife conflicts. [ABSTRACT FROM AUTHOR]

Islands are epicenters of animal extinctions and population declines. These losses exacerbate biodiversity loss and disrupt ecological services in areas of high endemism. Island defaunation is primarily driven by invasive mammalian predators, and mammal eradications are reversing population declines for some island species. Invasive mammal eradications may also have the capacity to restore ecological interactions, along with the recovery of island fauna. Here we show that invasive mammal eradication in fenced ecosanctuaries results in higher rates of bird foraging on fruit, and higher bird‐mediated seed dispersal, than in similar forests without mammal eradication. We further show that higher foraging and seed dispersal is related to higher densities of native bird species, after accounting for natural variation in fruit availability. For the many other systems globally that are under threat from invasive mammals, New Zealand's fenced ecosanctuary model offers a promising tool for restoring biodiversity and ecosystem services. [ABSTRACT FROM AUTHOR]

Conservation programmes aiming to suppress or remove invasive small mammal populations that threaten endemic fauna assume that eliminating an individual predator has the same effect as eliminating a conspecific in terms of decreasing risk to the prey species. However, marked between-individual variation in prey take could, at times, lead to uneven predation pressure. Such variation in the diets of introduced predators has long been hypothesised in New Zealand, suggesting that some observed rates of predation are not typical of the prey population as a whole. We used stable isotope analysis to estimate the isotopic dietary niches of stoats Mustela erminea (n = 51) caught in three New Zealand National Parks. We modelled δ13C and δ15N ratios from five tissue types to estimate the isotopic niche for each individual stoat, and for each population. The isotopic niche used by the population of stoats in Nelson Lakes National Park was substantially larger (5.3 ‰2) than for those at either Mt Aspiring National Park (3.1 ‰2) or Fiordland National Park (2.8 ‰2). Despite this, a measure of individual specialisation (proportional niche use) in stoats at Nelson Lakes National Park (0.4 ± 0.3) was similar to the other two sites. Collectively these data suggest a comparable degree of individual specialisation even within a more generalist population niche. This variability in the range of prey items taken by small carnivores, between populations and individuals of the same species, has consequences for how we design and monitor small mammal control programmes; for example, the threatened species outcomes observed in one area or time period may not be applicable to another. [ABSTRACT FROM AUTHOR]

Widespread resource extraction and habitat degradation have severely reduced functionally important subtidal mussel reefs globally. While methods for restoring oyster reefs are becoming increasingly well‐established, the development of techniques for the effective restoration of mussel reefs remain in their infancy and face biological and logistical challenges. This study investigated the potential use of subadult and juvenile green‐lipped mussels (Perna canaliculus) for mussel reef restoration with the aim of understanding factors related to subadult and juvenile mussel survival after transfer to the seafloor. Small‐scale (m2) field experiments were conducted subtidally in a New Zealand harbor to assess subadult and juvenile mussel survival after translocation to soft‐sediment seafloor, the efficacy of biodegradable substrate to support reef development, and whether juvenile mussel survival was related to changes in seeding density. Results demonstrated survival of cultured subadult and juvenile mussels after transfer to soft‐sediment seafloor only when completely protected from mobile predators. Attachment to biodegradable substrate alone was insufficient to prevent the loss of cultured juvenile mussels, while ~80% of wild subadult mussels survived translocation to the seafloor without predator protection—indicating a certain level of resilience. Changes in seeding density failed to prevent loss of cultured juvenile mussels. This study supports further consideration for incorporating cultured subadult and juvenile mussels into restoration, provided subadult and juvenile mussels can be protected until they become established as adults. [ABSTRACT FROM AUTHOR]

As New Zealand attempts to become predator free by 2050, transitioning aerial 1080 (sodium fluoroacetate) operations from predator control to complete predator removal has become an important research objective. Aerial 1080 operations may not remove every last target animal, but they may be able to remove a very high proportion (> 0.99). We trialled a modified [dual] aerial 1080 operation for the removal of brushtail possums (Trichosurus vulpecula), ship rats (Rattus rattus), and stoats (Mustela erminea) at large spatial scale. Our trial involved two toxin applications (TA#1 & TA#2), each preceded by two applications of non-toxic pre-feed bait. Different types of cereal baits and lures were used for each toxin application. Camera traps (n = 142; 200-1431 m asl) were used to detect the target species and to incidentally observe house mouse (Mus musculus), birds, and ungulates across the study area. The operation had no significant impact on the number of cameras detecting most birds and ungulate species; however, house mouse, blackbird (Turdus merula), and red deer (Cervus elaphus) were detected on significantly fewer cameras after TA#1 than before. Numbers of cameras that detected target species were significantly reduced for all three target species after TA#1, and significantly reduced again for possums after TA#2, when no stoats were detected on cameras and a small number of cameras detected rats. Mean relative abundance estimates based on camera trap indices (proportion of camera trap days that target species were detected) showed the operation appears to have removed over 99% of ship rats, stoats, and possums. [ABSTRACT FROM AUTHOR]

There is increasing interest in restoring native predators in order to regulate ecosystems and maintain biodiversity, but predator reintroductions are still controversial for complex social and ecological reasons. Few studies have examined predator restoration on islands or in ecosanctuaries, where highly endemic faunas have typically undergone precipitous declines and extinctions due to novel invasive predators, and translocations are used to restore species. Currently in New Zealand, discussions regarding predators typically focus on introduced mammalian pests, and the importance of native predators is frequently overlooked. We present a case study of the mesopredatory New Zealand weka (Gallirallus australis), a threatened flightless rail that provokes controversy among restoration practitioners due to concerns that it may decrease populations of other threatened species. We (1) review studies of weka diet and impacts on native and exotic fauna; (2) contrast prehistoric and contemporary predation webs focused on weka; and (3) consider the role of biocultural approaches in the management and restoration of socio-ecological systems with weka. Weka are opportunistic omnivores that can include vertebrates in their diet, and on small islands where weka can reach high densities there is some evidence that they may limit some prey populations. However, very few manipulative experimental studies measuring effects of weka on native species have been carried out, and such studies would be extremely valuable. Weka also consume invasive rodents and, if they obtain a sufficiently high density, may provide benefits in ecosanctuaries by limiting invasive mice populations. Māori historically harvested weka, and such harvest may now valuably limit weka numbers at certain island or ecosanctuary sites, perhaps replacing the effect of extinct avian competitors and apex predators. How weka and other native predators should be managed on islands depends on the value placed on ecosystem restoration, species-focused conservation, or biocultural enrichment. [ABSTRACT FROM AUTHOR]

Managing the impacts of invasive predators on islands is a priority for conserving global biodiversity. However, large islands and islands with substantial human settlement present particular challenges that can be broadly categorised as social and logistical. Around the world, managers concerned with island biodiversity are tackling increasingly ambitious projects, and some examples from Japan and New Zealand have been at the forefront. We used dialogues with managers, researchers, and community members, as well as our respective experience as wildlife researchers in Japan and New Zealand, to compare the challenges faced by wildlife managers in each country. We note similarities and differences between the two countries, and identify lessons from each that will help advance invasive species management on islands globally. Our observations from Japan and New Zealand show that considerable progress has been made in managing invasive predators on large, inhabited islands. Further progress will require more effective engagement with island residents to promote the goals of invasive species management, to find common ground, and to ensure that management is socially and culturally acceptable. Invasive predators are a global biodiversity threat, especially on islands. Predator management can be challenging on islands that are large, or that have substantial human populations. We explore examples from Japan and New Zealand, which have been at the forefront in addressing these challenges. [ABSTRACT FROM AUTHOR]

Population control of invasive mammal pests is an ongoing process in many conservation projects. In New Zealand, introduced wild domestic cats and mustelids have a severe impact on biodiversity, and methods to reduce and maintain predator populations to low levels have been developed involving poisoning and trapping. Such conservation efforts often run on limited funds, so ways to minimize costs while not compromising their effectiveness are constantly being sought. Here we report on a case example in a 150 km2 area in the North Island, New Zealand, where high predator numbers were reduced by 70-80% in an initial 'knockdown' trapping program, using the full set of traps available in the fixed network and frequent checks, and then maintained at low density using maintenance trapping with less frequent checking. We developed and applied a simulation model of predator captures, based on trapping data, to investigate the effect on control efficacy of varying numbers of trap sites and numbers of traps per site. Included in the simulations were captures of other, non-target, introduced mammals. Simulations indicated that there are potentially significant savings to be made, at least in the maintenance phase of a long-term predator control programme, by first reducing the number of traps in large-scale networks without dramatically reducing efficacy, and then, possibly, re-locating traps according to spatial heterogeneity in observed captures of the target species. [ABSTRACT FROM AUTHOR]

Human colonization of islands has resulted in the reduction or loss of many native species, and the introduction of non‐native species, producing novel ecosystems. The impacts of these changes on mutualistic plant–animal interactions have received considerable attention, but the potential effects on some antagonistic interactions, such as seed predation, are less thoroughly understood, and often overlooked.Using three archetypal island groups—New Zealand, the Mascarenes and Hawaiʻi—we compare the taxonomic richness and functional diversity of vertebrate seed predators from prehuman and contemporary ecosystems. We scored species on several traits relevant to seed predation, then clustered species into functionally similar groups using hierarchical clustering.These archipelagos once supported between 19 and 24 species of exclusively avian seed predators (representing two to four orders) ranging from large, flightless herbivores to small, volant finches and parrots. Following human arrival, 63%–89% of these species went extinct, and between 12 and 23 non‐native seed predators were introduced. Contemporary seed predator faunas consist of between 14 and 26 species (representing six to seven orders), dominated by non‐native granivorous birds and omnivorous mammals.Our results reveal several examples in which non‐native species may be functionally similar to extinct seed predators, but most non‐native species are functionally different from extinct species, and therefore may be introducing novel seed predation pressures for insular ecosystems. Mammalian seed predators are especially functionally different from the native avian seed predators, as their teeth and widespread habitat distribution allow them to destroy a more diverse range of seeds, including the largest seeds.We highlight the need to understand how these altered seed predator communities are affecting native plant populations, particularly in the context of reduced pollination and seed dispersal. More broadly, we argue that antagonistic interactions are an integral part of any ecosystem, and therefore must be understood if we are to achieve more holistic restoration frameworks for insular ecosystems. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

In animals with indeterminate growth, such as predatory fishes, mouth size is related to, and increases with, body mass of the organism. As fishes grow in body size, they can consume larger-bodied prey items at potentially-higher trophic levels. Therefore, body size should predict trophic position. Trophic position (TP) is useful for describing energy flow between biota, giving a more comprehensive picture of aquatic food webs, but the factors that influence the body-size–TP relationship are unclear. Additionally, stable isotope-derived TP and body-size relationships are untested for temperate freshwater fishes. Using linear mixed-effects models, we tested fish body mass as a predictor of TP across 6 species of temperate freshwater fish (n = 921 total individuals) sampled from 110 stream reaches in New Zealand, and we evaluated habitat factors (flood disturbance and stream size) likely to affect trophic structure of stream fish assemblages. Supporting ecological theory, but contrasting with some previous findings in marine and tropical environments, we found that TP was positively associated with body size across all species. Habitat factors did not affect fish TP. However, stream network spatial factors included in models as random effects explained the majority of variance in TP across species. Thus, while our study shows that New Zealand temperate freshwater fish body size is positively associated with stable isotope-derived TP, researchers will need to account for catchment-specific spatial factors to make accurate inferences about TP based on body size. [ABSTRACT FROM AUTHOR]

Predator avoidance behaviors are assumed to occur at a cost to the potential prey. The invasive New Zealand Mud Snail (Potamopyrgus antipodarum) exhibits several behaviors that appear to reduce the probability of predation when the snail chemically detects potential predators in both its native and invaded range. We conducted 2 experiments to determine if these predator-induced behavioral changes come at a cost of growth to the snail. In the 1st experiment, we exposed juveniles of 4 different populations (3 invasive and 1 New Zealand native) to plain water and to water with odor from a potential fish predator (Blacknose Dace, Rhinichthys atratulus). In the 2nd experiment, we exposed juvenile snails of 1 invasive population to plain water, water with crayfish odor, water with crayfish odor where the crayfish had been fed snails, and crushed snail odor. In both experiments we measured the change in length of the snails after ~7 wk. We found that different populations grew at different rates, and that fish odor resulted in snails growing at a slower rate than snails exposed to plain water. We found weak evidence that snails from different populations were affected differently by fish odor. In the 2nd experiment, we found that only odor from crayfish feeding on snails resulted in a reduced growth rate. These results demonstrate that the behavioral response to a chemical cue produced by a predator in this system comes at the cost of growth, which is likely caused by reduced foraging. The fact that invasive populations retain the ability to detect and behaviorally respond to predators, despite the growth cost, suggests that behavioral flexibility may play a role in the invasion success of this species. [ABSTRACT FROM AUTHOR]

The eradication of invasive predators from islands is a successful technique to safeguard seabird populations, but adequate post‐eradication monitoring of native species is often lacking. The Whenua Hou Diving Petrel (Pelecanoides whenuahouensis; WHDP) is a recently‐described and 'Critically Endangered' seabird, restricted to Codfish Island (Whenua Hou), New Zealand. Invasive predators, considered the major threat to WHDP, were eradicated on Codfish Island in 2000. However, estimates of WHDP population size and trends remain unknown, hindering assessments of the success of the eradications. We collated intermittent burrow counts (n = 20 seasons) conducted between 1978 and 2018. To estimate the population growth rate (λ) before and after predator eradications, we used log‐linear models in a Bayesian hierarchical framework while retrospectively accounting for differences in detection probabilities among burrow counts, due to differences in effort, marking and timing. The number of WHDP burrows was estimated at 40 (36–46) in 1978 and 100 (97–104) in 2018. The pre‐eradication λ was estimated at 1.023 (0.959–1.088), while the post‐eradications λ was estimated at 1.017 (1.006–1.029). The WHDP population appears to be increasing, yet the rate of increase is low compared to other Procellariiformes following predator eradications. The comparatively low post‐eradication λ, combined with an apparent lack of change between pre‐ and post‐eradication λ, indicates that additional threats might be limiting WHDP population growth and that further conservation management is required. The continuation of affordable and simple, albeit imperfect, monitoring methods with retrospective corrections facilitated the assessment of invasive predator eradications outcomes and should guide future management decisions. An abstract in Te Reo Māori (the Māori language) can be found in Appendix S1. [ABSTRACT FROM AUTHOR]

Conservation policy in New Zealand is centred around an objective to totally eradicate three invasive species; the ship rat (Rattus rattus), the brushtail possum (Trichosurus vulpecula) and the stoat (Mustela erminea), by 2050. The preferred control method to achieve this is large scale poisoning operations with 1080 and similar toxins. This project is backed up by governmental and non-governmental agencies and surrounded with discourse of 'war' and 'invasion'. The 'Big Three' predators are endowed with sinister motives as a means of mobilising support. This self-described 'war' is evaluated in terms of 'just war' theory and found wanting. In particular there are issues with the recruitment of children for killing, humiliation of combatants, questionable economic motives for the 'war', deception by government agencies, lack of consultation, a lack of consideration of alternatives, the use of excessive suffering, and unrealistic expectations. An alternative paradigm of 'compassionate conservation' is proposed for New Zealand. Instead of trying to get back to a stable pre-colonial state of nature, I propose a holistic approach that respects both ecosystems and their members and takes into account new understandings of ecosystems as dynamic processes. [ABSTRACT FROM AUTHOR]

Parasites manipulating their host to facilitate trophic transmission is a widespread and diverse phenomenon. Trematode eye‐flukes in the family Diplostomidae infect a variety of fish species as metacercariae, many residing in the eyes. A recently described diplostomid, Tylodelphys darbyi, from the South Island of New Zealand has been found to infect common bully Gobiomorphus cotidianus, an endemic freshwater fish. Within the fish, the metacercariae move about freely in the liquid parts of the eye and are quite large. We hypothesized that increasing intensity of T. darbyi infection will result in increasing visual impairment, thus reducing the ability of G. cotidianus to identify and react to a predatory threat. To test this hypothesis, we performed experiments to (a) examine the fish's reaction to a purely visual predator cue and (b) test their ability to avoid simulated predation under natural levels of infection. Among the 64 fish used in our experiments, T. darbyi had a prevalence of 98.7% with an average of 17.6 worms per fish. However, there was no relationship between T. darbyi intensity and either the fish's reaction to a visual predator stimulus or their ability to escape a simulated predator. Our findings indicate that despite being present in large numbers in the eyes of its fish host, the parasite appears incapable of improving its chances of trophic transmission to its avian definitive host. The results also suggest that the fish G. cotidianus could be using other senses (e.g., olfaction and lateral line) to compensate for visual impairment, and detect and respond to predators. [ABSTRACT FROM AUTHOR]

Behavior can play a large role in invasion success. Of particular importance may be the ability of an invader to detect and respond to unfamiliar potential predators. We examined a behavior related to dispersal in populations of the New Zealand mud snail (Potamopyrgus antipodarum) in response to chemical cues from crayfish and piscine predators. Populations of the snail isolated from North America and its native New Zealand were used in two separate experiments. In both experiments, groups of snails were placed in water either with or without predator cues, and the number of snails found floating attached to the surface tension of the water after ten minutes was noted. In the first experiment, a crayfish odor cue was used (from Procambarus clarkii), and, in the second, two fish, blacknose dace (Rhinichthys atratulus), and separately zebrafish (Danio rerio), were used to provide the chemical cues. In both experiments there was significant variation among populations in the proportion of snails that exhibited the floating behavior, with native populations tending to exhibit less floating behavior. The snails generally increased floating behavior in response to both crayfish and blacknose dace but not to zebrafish. In addition, we found no differences between populations of snails in their response to predator cues. Surprisingly, we also found that there were differences in floating proportions between populations of the same invasive clonal genotypes. These results suggest this behavior, which may be related to dispersal within water bodies, may be important in partially explaining the invasion success of the most common invasive clones in North America. [ABSTRACT FROM AUTHOR]

The endemic fauna of New Zealand evolved in the absence of mammalian predators and the introduction of the latter has been devastating. There have been numerous avian extinctions and 80% of the extant native avian taxa are currently threatened or at risk of extinction. Declines continue, and a fundamental change in predator management is required. In 2016 came the announcement of the ambitious Predator Free 2050 (PF 2050) programme, which aims to eradicate rats, mustelids, and Brushtail Possums from New Zealand by 2050. This paper reviews some of the many techniques being discussed or developed to implement the programme. Existing techniques are being refined and new tools are being developed. Research on new toxins, including those with potentially higher species specificity, is under way, and novel baits and toxin-delivery devices are being developed. Existing trap designs are being refined, and new self-resetting traps capable of multiple kills have been developed. Research is also under way on new lures and repellents. Eradications may be achieved in stages, and barriers (both natural and artificial) will be needed to protect areas already cleared. Current techniques will probably be inadequate to effect nationwide eradications, and new tools (possibly based on genetic technologies) will probably be required. Regulatory hurdles will need to be overcome, and community consultation and support (social licence) will be required throughout the programme. The use of some new technologies may be contentious, and not every new idea will necessarily be adopted. Technical, social, and organisational challenges exist, and national and international collaboration will be required for PF 2050 to succeed. [ABSTRACT FROM AUTHOR]

Quantifying the distribution of prey greatly improves models of habitat use by marine predators and can assist in determining threats to both predators and prey. Small epipelagic fishes are important prey for many predators yet their distribution is difficult to quantify due to extreme patchiness. This study explores the use of recreational grade echosounders (RGE) to quantify school characteristics of epipelagic fish and link their distribution to that of their predators at Banks Peninsula, New Zealand. The hydro-acoustic system was ground-truthed with 259 schools of epipelagic fish. During 2015 and 2016, 136 hydro-acoustic surveys were conducted with concurrent observations of Hector’s dolphin (Cephalorhynchus hectori) and little penguins (Eudyptula minor). The relative abundance of the two predator species during surveys was modelled according to the relative abundance of potential prey using generalised additive mixed models. Schools of epipelagic fish were readily detected by the RGE system and were more abundant in summer compared to winter. The models performed well, explaining 43% and 37% of the deviance in relative abundances of dolphins and penguins respectively. This is the first study to link the distribution of Hector’s dolphin to that of their epipelagic prey and confirms the utility of RGE in studies of habitat use in marine predators. Limitations associated with a lack of formal acoustic calibration and data formatting can be overcome and would make RGE valuable, inexpensive tools for investigating variability in populations of small pelagic fishes. [ABSTRACT FROM AUTHOR]

During the nineteenth century, three species of mustelids were successfully imported into New Zealand to act as natural enemies of rabbits. This article describes a series of serious proposals to import seven other predatory species, all of which were fortunate failures. The red fox arrived only as a tame pair, which died without issue, and further imports were prohibited. Mongooses arrived in what could have been sufficient numbers to establish, but died out when released. Five further proposals for species' importations were never enacted, but the fact that they were suggested at all indicates the strength of the imperative to find a way to control 'the rabbit nuisance'. [ABSTRACT FROM AUTHOR]

The broom leaf beetle (Gonioctena olivacea) and the Honshu white admiral butterfly (Limenitis glorifica) have been introduced into New Zealand as biocontrol agents of the weeds Scotch broom (Cytisus scoparius) and Japanese honeysuckle (Lonicera japonica) respectively. However, neither agent has been successful yet. Larval predation of these species could be a factor affecting their success, and this hypothesis was tested using various predator-exclusion treatments. Survival of broom leaf beetle larvae increased c. five-fold by sleeving Scotch broom seedlings in fine mesh. In contrast, survival was unaffected by excluding either crawling predators using sticky barriers or larger predators using chicken wire. Survival of Honshu white admiral butterfly larvae increased c. ten-fold by excluding either crawling predators using sticky barriers or flying predators using a fine-mesh sleeve. Simultaneously excluding both crawling and flying predators resulted in a c. 23-fold increase in survival. These results suggest that larval predation could be limiting the populations of both broom leaf beetle and Honshu white admiral. Future biocontrol programmes could prioritise candidate agents accordingly. [ABSTRACT FROM AUTHOR]

In 2016, the New Zealand Government announced a policy to rid the country of key introduced predators (possums (Trichosurus vulpecula), ship rats (Rattus rattus), Norway rats (R. norvegicus) and mustelids (Mustela spp.)) by 2050. An interim goal under this policy is to remove all mammalian predators (the key species as well as mice (Mus musculus), kiore (R. exulans), cats (Felis catus), pigs (Sus scrofa) and hedgehogs (Erinaceus europaeus)) from island nature reserves by 2025. We identify the New Zealand islands over one hectare managed as reserves by the Department of Conservation (DOC) that have mammalian predators that can be eradicated. There are over 850 islands, islets, stacks and vegetated rocks in the New Zealand archipelago. We exclude islands in lakes and rivers and those smaller than one hectare, which leaves 616 islands, less than half of which are under some form of reserve status (286 islands entirely managed by DOC and 13 under mixed tenures but with some reserve land). One or more mammalian predators are known to occur on 48 of these islands, with the Government's 2050 target species on 42 islands and other predators (in the absence of the target species) on six islands. The Government's 2025 goal nominates one class of reserve, nature reserves. Of the 48 islands, just four islands are classed as nature reserves -- two (Mauitaha and Araara Islands) with protected kiore in the Hen and Chickens group and two in the Auckland Islands group (Auckland with mice, cats and pigs; and Masked with mice and cats) -- i.e. none with the key species of the wider 2050 goal. Therefore, we consider other reserve classes but place more or less strict risks of reinvasion, as indexed by known swimming ranges of the predators, to judge the feasibility of eradication. Relaxing the reserve class of the island, but not our selection of swimming ranges, results in 15 candidate islands where all mammalian predators present could be eradicated for the 2025 interim goal. Decisions on which islands to select for the programme need to consider costs and other constraints to eradicate different combinations of predators, and whether the island and its predators provide templates for the wider vision of a predator-free New Zealand, i.e. whether any of the key 2050 predators are present, the size of the island, and/or the presence of human inhabitants that complicate the predators to be targeted or constrain the use of some control methods. [ABSTRACT FROM AUTHOR]

Programs to conserve native fauna in invaded ecosystems often aim to reduce the impacts of alien predators. This approach can lead to unexpected outcomes in the native and the remaining invasive components of restored ecosystems. In New Zealand, suppression and eradication of invasive mammalian predators are well-established conservation strategies, particularly on offshore islands and in mainland ecosanctuaries. Predator control has achieved important conservation gains over increasingly large areas but these can be offset by the ecological release of other uncontrolled pest species. In addition, novel ecosystems created by selective predator control and reintroductions of locally extinct or depleted native species may have unexpected trajectories as they evolve. Effective conservation requires new techniques for controlling entire suites of invasive predators over large areas, routine monitoring of the conservation outcomes of predator control, and better understanding of how modified, and in some cases reconstructed, seminatural ecosystems change when invasive predators are removed. [ABSTRACT FROM AUTHOR]

A major challenge in controlling overabundant wildlife is monitoring their populations, particularly as they decline to very low density. Camera traps and wildlife detector dogs are increasingly being used for this purpose. We compared the cost-effectiveness of these two approaches for detecting feral cats (Felis catus) on two pastoral properties in Hawke's Bay, North Island, New Zealand. One property was subject to intensive pest removal, while the other had no recent history of pest control. Camera traps and wildlife detector dogs detected cats at similar rates at both sites. The operating costs of each method were also comparable. We identify a number of advantages and disadvantages of each technique, and suggest priorities for further research. [ABSTRACT FROM PUBLISHER]

New Zealand's diverse lizard fauna is under threat, particularly from predation by invasive mammals and ongoing habitat destruction. Advances in genetic techniques have greatly enhanced our understanding of the lizard fauna. Previously sparse island populations of species have recovered strongly following eradication of pest mammals and translocations of lizards to newly mammal-free islands have boosted security for some species. Recent success with intensive predator control and predator-proof fencing on the mainland shows promise for lizard populations in easily accessible sites. However, the plight of many species whose range does not include pest-free islands remains precarious and taxonomic uncertainty means we do not yet understand the full suite of species in need of protection. Further advances in predator control techniques and increased funding for lizard conservation management are needed to prevent species extinctions. [ABSTRACT FROM AUTHOR]

The mitigation of the impact caused by introduced mammalian predators is a priority for conservation managers. Reducing predator population numbers is the most realistic strategy in mainland areas or large islands, and could be a feasible alternative to pest eradication. However, the success of control campaigns depends not only on removal of resident individuals, but also on managing reinvasions facilitated by connectivity with surrounding source populations. We combined niche analysis and fine-scale movement analyses of feral cats ( Felis silvestris catus ) to identify least-cost corridors from sources surrounding controlled areas of the ecologically sensitive area of Tasman Valley and Aoraki/Mt. Cook National Park, New Zealand. Intensive control of exotic predators has been executed during the last ten years in this area, where they pose a threat to native species such as endangered ground-nesting birds. Species distribution models revealed that cat distribution in the region was limited by its main prey, the European rabbit, and to mid-elevation (~ 1600 m) areas. Using GPS-tracking data and step-selection functions, we found that cats moved in an optimized fashion suggesting a maximum energy gain associated with high rabbit presence, while avoiding landscape obstacles such as rugged terrain. Connectivity between the high probability of cat presence in source and destination locations (in the control area) was facilitated by 1–3 corridors between valleys and multiple paths within valleys. Identification of least-cost paths, rooted in ecological and behavioral mechanisms underlying space use, can identify realistic putative corridors for focused implementation of control measures for introduced species in ecologically sensitive areas. [ABSTRACT FROM AUTHOR]

The impacts of introduced mammalian predators on the viability of bird populations in forest, river and coastal habitats in New Zealand are well known. However, a common understanding of their impacts in freshwater wetlands is lacking. We review evidence for impacts of introduced mammalian predators on freshwater birds, particularly specialist species restricted to wetlands, and use this information to make predictions about freshwater species likely to be vulnerable to predation. Extinctions and significant declines of freshwater species have been numerous since humans introduced mammalian predators to New Zealand. Anecdotal evidence links predation to the loss of 11 of 14 extinct birds that would have inhabited wetlands. Thirty extant species, particularly ground-nesting species, are still under threat from mammalian predators. All introduced mammalian predator species are abundant and/or widespread in New Zealand wetlands and most have been confirmed to prey upon freshwater bird species. While their precise impacts on the long-term viability of threatened bird populations have not been evaluated, evidence suggests that predation is a serious threat, warranting predator control. An evaluation using documented predation events and ecological traits suggests that six threatened wetland specialists are at high risk of predation: Australasian bittern (Botaurus poiciloptilus), banded rail (Gallirallus philippensis), brown teal (Anas chlorotis), fernbird (Bowdleria punctata), marsh crake (Porzana pusilla), and spotless crake (P. tabuensis). Research is needed on the ecology and behaviour of mammalian predators in wetlands to help understand their impacts on long-term viability of bird populations and to assist in developing and monitoring predator control programmes. [ABSTRACT FROM AUTHOR]

Control operations for invasive ship rats, Rattus rattus, in New Zealand forests are often followed by increased house mouse, Mus musculus, detections suggesting rats suppress mice. A potential mechanism is intraguild predation, either by interference competition or as simple predatory behaviour. If aggression by rats towards mice is mainly competitive, it should include threat and display features associated with, for example, intraspecific fighting. If predatory, it should lack these features and be associated with feeding. In the first of two captive experiments we observed interactions between paired, live rodents, either side of a wire-mesh screen, and found that most rats were aggressive to mice. This aggression lacked threat and display characteristics typical of encounters with conspecifics and was rarely reciprocated by mice. In a second experiment, euthanized mice were drawn by a line through cages occupied by rats fed either a restricted or unrestricted diet. Rats of both groups attacked and restrained the euthanized mice, and all rats that interacted with the mice ate at least part of them, although food-restricted rats tended to eat more. As the aggressive response of ship rats towards mice lacked threat and display features and was related to feeding, we conclude that it resembles predatory behaviour. Our findings provide a better understanding of the interactions between ship rats and house mice, which hinder their management where they coexist as damaging invaders. However, further research is required to determine whether the results of our captive experiments are consistent with wild rat behaviour. [ABSTRACT FROM AUTHOR]

1. Within-species phenotypic variation is hugely variable and may play a role in determining the range of habitats a species can exploit. Our study addressed two main questions: 1. does phenotypic variation allow some species (i.e. habitat-generalists) to use heterogeneous habitats and 2. are habitat-generalists more variable than species occupying relatively homogeneous environments (i.e. habitat-specialists)? 2. We examined the morphology of the common bully ( Gobiomorphus cotidianus), a habitat-generalist eleotrid fish found in lakes and rivers throughout New Zealand. We also compared the level of morphological variability in common bullies with that in the closely related redfin bully ( Gobiomorphus huttoni), a habitat-specialist of moderate- and fast-flowing rivers. 3. Common and redfin bullies were collected from the South Island of New Zealand. A series of body and fin measurements were made, and cephalic dorsal head pores of the mechanosensory lateral-line system were counted. The pores and associated canal neuromasts are important for prey detection and predator avoidance in other species, particularly, in turbulent conditions where the effectiveness of superficial neuromasts may be compromised. 4. The common bully had more dorsal head pores in fish from rivers than in those from lakes. This pattern was apparent only in adults, suggesting that selective pressures associated with adult habitat, be it rivers or lakes, are responsible. 5. As expected, there was greater phenotypic variability in the generalist common bully than in the specialist redfin bully, particularly with regard to the sensory pores, suggesting their importance for survival in turbulence. 6. We identified habitat-related patterns in phenotypic variability in a generalist species and demonstrated a link between phenotypic variability and habitat breadth. Variation in the common bully may explain its ability to occupy a range of habitats. [ABSTRACT FROM AUTHOR]

Efforts to eradicate multiple mammal pests from offshore islands and fenced mainland 'habitat islands' often fail to remove mice, and such failures can result in a dramatic change in the food-web whereby the removal of larger mammal pests facilitates a population explosion of mice through predator and competitor release. We investigated the ecological responses of house mice to the removal of mammalian predators from a 500-ha fenced sanctuary at Tawharanui, northern New Zealand. Data on population structure and body condition of mice trapped in 2007, in four habitat types within the sanctuary, were compared with baseline data collected in 2001, before mammal control operations commenced. We hypothesized that: (i) in the absence of mammalian predators mouse densities would increase in all habitat types that provide vegetation cover, and (ii) in the absence of mammalian competitors mice would become heavier due to greater access to food resources. Mouse densities were significantly higher in 2007 than in 2001 in three habitat types. The high density of mice in forest - where none were trapped prior to control - suggests a competitive release, in which mice profited from the removal of ship rats. No mice were caught in the presence of ship rats on a forest trap-line at a control site outside the sanctuary. Mice trapped in 2007 were significantly heavier than those trapped in 2001, and significantly heavier than mice trapped at the control site. Greater access to food in the absence of competing and predatory mammals probably explains the heavier body weight of Tawharanui mice. There has been a significant change in the mammalian food-web at Tawharanui, such that the house mouse is now the primary pest. A rapid and dramatic increase in mouse numbers is likely to adversely impact invertebrates and seedling recruitment, which in turn could affect ecosystem functions. [ABSTRACT FROM AUTHOR]

Cats (Felis catus) are known predators of New Zealand bats, although all records to date have been from domestic cats thought to have caught foraging bats. We outline the first evidence of predation of short-tailed bats (Mystacina tuberculata rhyocobia) at a roost tree. A total of 156 individual bat wings (78 pairs) and 22 intact bodies were found at the base of two colonial roost trees in Rangataua Forest on the southern slopes of Mount Ruapehu, Central North Island in New Zealand, over a period of 7 days. Assuming a pair of wings belonged to one individual, at least 102 bats were killed by a male cat caught in a live trap at the base of one roost tree. No more deaths were recorded after its capture. [ABSTRACT FROM AUTHOR]

Abstract: The ‘new species association’ biological control approach is based on the ecological principle in which a natural enemy is used that has not coevolved with a pest. The recent incursion of the tomato–potato psyllid (TPP), Bactericera cockerelli to New Zealand offered a unique opportunity to investigate the potential of a new species association for biological control of this pest. This laboratory-based study investigated the potential for a new species association between two New Zealand naturalized coccinellids, Cryptolaemus montrouzieri and Cleobora mellyi, and TPP. A third naturalized New Zealand coccinellid, Scymnus loewii, was compared as a potential ‘old association’. We conducted two experiments to determine consumption rate and feeding behavior, respectively, of adults and fourth-instar larvae of the three coccinellid species on mixed instars of TPP nymphs, using tomato and potato leaflets, and a no-leaflet control. C. montrouzieri consumed up to 30 psyllids over 24h, depending on leaflet type and predator life stage. C. mellyi adults and larvae were the most voracious predators of psyllids, consuming up to 100 TPP over 24h. Adult C. mellyi spent more time feeding on psyllids in the control (56%) and potato leaflets (30%) than on tomato leaflets. Larvae spent 79% more time feeding on the no-leaflet control, compared to the potato (24%) and tomato leaflet (14%) treatments. S. loewii consumed relatively few psyllids on all three substrates (<10 over 24h), and spent less time feeding compared to the other two species. By demonstrating that these predators will consume this psyllid, our results suggest that a new species association may potentially exist between C. montrouzieri, C. mellyi and the TPP. [Copyright &y& Elsevier]

Abstract: Predation is a major factor in ecology, evolution and conservation and thus its understanding is essential for insights into ecological processes and management of endangered populations of prey. Here we conducted a spatially (main island through to offshore islets) and temporally (1938–2005) extensive meta-analysis of published nest predation rates in New Zealand songbirds. We obtained information on nest predation rates from 79 populations (n =4838 nests) of 26 species of songbirds belonging to 17 families. Nest predation rates increased from southwest to northeast and also across the last 60years (by 15–25% points in both cases). We identified a major impact of exotic mammalian predators. Nest predation was lowest in areas where no exotic predators were present (12.8%), higher in areas with ongoing predator control (33.9%), and highest in areas without control that had the full set of exotic and native nest predators (47.5%). Surprisingly, nest predation rates were higher in introduced as compared to native species. Our analyses demonstrated that human-caused factors (introduced predators and prey) overrode factors such as nest type and habitat identified as important in predicting nest predation in North America and Europe previously. [Copyright &y& Elsevier]

Predation of eggs and/or chicks is the main cause of nesting failure in birds. Nest predation has been studied in many habitats in New Zealand, but few studies have been conducted in urban ecosystems. Twenty-one nests of four bird species (blackbird [Turdus merula], song thrush [Turdus philomelos], fantail [Rhipidura fuliginosa], and silvereye [Zosterops lateralis]) were monitored over one breeding season in Hamilton using time-lapse recordings. Five predation events were filmed (two by cats [Felis catus], and three by ship rats [Rattus rattus]), 10 nests successfully fledged chicks and 6 nests failed owing to poor weather, desertion, or unknown events. Although the sample size was small, our data suggest that nesting success may be higher in urban Hamilton than in other unmanaged habitats where predation rates can exceed 80%. We recommend that future studies of nesting success in urban birds should also focus on the fates of fledglings, as anecdotal evidence suggested that predation rates may have been highest at this stage. [ABSTRACT FROM AUTHOR]

Cross-ecosystem transfers of resources could alter the life history traits of consumers in adjacent systems by changing the nature and availability of prey. However, large-scale influences, such as natural disturbances, that control the magnitude of prey subsidies are likely to modify these effects. To investigate impacts of cross-ecosystem subsidies on the life history traits of a riparian predator we measured the size, sex and condition of riparian fishing spiders ( Dolomedes aquaticus) across a gradient of flooding frequency and intensity. These spiders rely on adult aquatic insects for a large proportion of their diet and previous research demonstrated that increased flooding decreased the abundance of aquatic insect prey. In this study, laboratory experiments indicated that increased prey availability hastened the first moult of the spiders after winter and decreased the propensity for cannibalistic interactions of individuals of the same size. However, despite the likely positive influences of increased food supply, in the field the highest abundance and proportion of large, potentially reproductive females occurred at the most flood-prone rivers, where aquatic prey availability was the lowest. It is likely that other factors modified by the disturbance regime, such as habitat availability, flood-related mortality and intra-specific interaction rates, altered the influence of cross-ecosystem subsidies on the life history traits of these spiders. Thus, our results indicate that disturbance-related effects can flow across ecosystem boundaries and alter the life history traits of predators relying on allochthonous resources. [ABSTRACT FROM AUTHOR]