Fox Predation Research Articles

Evidence of anthropogenic subsidisation of red foxes in a national park important for breeding wading birds

AbstractThe red fox (Vulpes vulpes) is a generalist mesopredator found throughout the UK. It has been linked to national declines in native wildlife, especially ground-nesting birds such as waders. In the New Forest National Park, nest predation and poor chick survival is primarily responsible for low breeding success of Eurasian curlew (Numenius arguata), a species of high conservation concern. To reduce predation losses, foxes are lethally controlled by wildlife managers. Here, we identified the major food resources that are being exploited by foxes in the New Forest area and examined temporal and spatial patterns in the presence of specific food categories, with special reference to anthropogenic food. Stomachs from foxes culled in curlew breeding areas were collected from April 2021 - July 2022 and the contents of these stomachs were quantified. Foxes exhibited a highly varied diet with no single food category predominating. Anthropogenic food comprised 14% of the overall diet, with its presence predicted by proximity to human settlements and other infrastructure. We also estimated the total annual volume of anthropogenic food consumed by the fox population and by extension how many individual foxes this volume of food could support in isolation. According to these calculations, at present the number of foxes subsidised by anthropogenic food is approximately 64.8% (50.2–79.7%) of those removed by culling per year. Our findings highlight that better local food sanitation and education should become important parts of a more holistic management approach to reduce the burden of fox predation experienced by breeding waders.

Reintroduction to the edge of its range: quenda (Isoodon fusciventer) to Wadderin Sanctuary in the eastern wheatbelt of Western Australia

Context Quenda (bandicoots, Isoodon fusciventer) have shown a major decline in range since European settlement, contracting to the more mesic coastal and forest zones in south-west Western Australia. Key actions to recover this species include broad-scale fox control, cat control and reintroductions. Most reintroductions have been to coastal and forest habitats. Aims To monitor the reintroduction of quenda to fox-free habitat of Wadderin Sanctuary in the wheatbelt of Western Australia, close to the eastern and drier margin of the species’ former range. Methods Relative abundance of the population was monitored over a 12-year period by regular standardised trapping throughout the sanctuary. Key results Quenda were reintroduced in 2010 and have persisted for >12 years. They were protected from fox predation by an exclusion fence, but were subject to a low level of cat predation for the first 8 years. Quenda showed both a ~20% drop in mean body condition over time and a trend of decreasing number of pouch young per female over time, likely a result of a succession of dry years and intra-and inter-specific competition for food resources. However, despite this, the index of abundance suggests that quenda numbers substantially increased, aided by high annual recruitment, in years following removal of the feral cat. Conclusions Quenda appear resilient at this site despite consecutive years of very low rainfall and apparent competition for food resources. Implications Quenda seem able to persist on the drier margin of their former range when protected from high levels of predation.

Movement ecology and minimum density estimates of red foxes in wet grassland habitats used by breeding wading birds

The red fox (Vulpes vulpes) is a widely distributed generalist meso-predator implicated in declines of wading bird populations. In the wet grassland habitats where waders breed, wildlife managers work to mitigate fox predation risk to waders during the nesting period through lethal and non-lethal control methods. However, limited knowledge on fox movement ecology in these habitats makes it difficult to design effective management strategies. We used GPS telemetry to understand fox home range size, daily activity and movement patterns, and how these metrics may vary among wet grassland sites with different management. We caught and GPS-tagged 35 foxes in the March–June wader nesting period on two wet grassland sites in central southern England; Britford during 2016/17 and Somerley during 2018/19. We estimated home range areas from location data using local convex hulls, and from these estimates we derived the minimum fox density at each site and year. Daily activity patterns and movement behaviour of each fox were obtained using both telemetry and trail camera data. Mean fox home range area at Britford (0.21 km2, SE = 0.025) was significantly smaller than at Somerley (0.68 km2, SE = 0.067), and estimated minimum densities were around four times higher (Britford = 10.6 foxes/km2, Somerley = 2.4 foxes/km2). Foxes were more active and moved faster during twilight and night hours, but both telemetry and camera data indicate they were also active for one-third of daylight hours. Distances moved per day were variable between foxes but generally smaller at Britford. We also found evidence for dispersal during spring, with movements of up to 19 km per day. Home ranges at both wet grassland sites were smaller than comparable sites elsewhere. These indicated foxes were living at exceptionally high densities at Britford, where there is no fox control, increased food availability and where waders no longer breed. Spatio-temporal movement patterns were closely related to home range metrics, with higher levels of fox activity at Somerley, where home ranges were larger. The movements of itinerant and dispersing foxes during the nesting period suggests that lethal control would need to be very intensive to be effective. The likely anthropogenic food subsidy of fox density at Britford suggests that controlling access to similar food resources would help reduce predation pressure on breeding waders.

STATE OF POPULATIONS AND BREEDING BIOLOGY OF THE HORNED PUFFIN (<i>FRATERCULA CORNICULATA</i> ALCIDAE, CHARADRIIFORMES) IN THE NORTHERN PART OF THE SEA OF OKHOTSK

The breeding biology of the Horned Puffin, Fratercula corniculata, was studied in 1989–2019 on Talan Island, Tauiskaya Bay, Sea of Okhotsk. Even though the estimates of the population size of the Horned Puffin made in the early 1990s and 2007–2008 (90–100 and 75–112 thousand individuals, respectively) failed to reveal its dynamics due to different study methods applied, data on the nesting density in these periods indicated its increase by more than 30%. In subsequent years, higher bird densities were recorded on the surface of model screes. Taking into account these data, the maximum numbers of horned puffins on the island could reach 166 thousand individuals. Depending on ice cover conditions, the dates of the onset of egg laying varied between June 6 in 1990 and June 17–18 in 1987, 1999 and 2001, the average long-term date being June 11. Chicks in different years started hatching between July 17 to 29, the average long-term being July 22. The weight of hatchlings varied from 35 to 53 g (mean 47.2). The average weight of monthly chicks in 1999–2006 ranged from 145 to 329 g, in some individuals from 80 to 410 g. The average age of the young birds captured on the ground was 44.7 days. The first individuals were recorded in different years at the end of August (August 27–30) and at the beginning of September (September 2). According to indirect estimates, fledglings left nest burrows between September 10 and 20, to end in late September to early October. The average weight of fledglings heading to the sea in 1987, 1988, 1989 and 1991 was 349, 338, 347 and 318 g, respectively. The wing length varied from 153 to 156 mm. The reproductive success of horned puffins varied from 10.3 to 90.5% (on average 56.4%), the hatching success from 19.8 to 95.2% (on average 75.5%), the fledging success from 26.7 to 100% (on average 74.6%). In the long-term aspect, the breeding success was most often quite high, with the exception of 2001, 2009–2012 and 2014–2015, when this indicator was lower than the long-term average. Among terrestrial mammals, red foxes cause the main threat to adult horned puffins living on the island, as well as to their clutches and chicks descending to the sea, but foxes fail not render a significant impact on the state of the horned puffin population. Due to their small numbers, these predators control only a certain parts of the island, while horned puffins are dispersed almost throughout its territory, where in most cases they are safe from fox predation. Voles act as utilizers of already abandoned eggs. Slaty-backed gulls and ravens do not attack adult horned puffins, but willingly eat adult birds found dead, as well as dead or still alive chicks during their descent to the sea. Adult birds are also taken, albeit rarely, by Steller’s sea eagles.

Extreme events, trophic chain reactions, and shifts in phenotypic selection

Demographic consequences of rapid environmental change and extreme climatic events (ECEs) can cascade across trophic levels with evolutionary implications that have rarely been explored. Here, we show how an ECE in high Arctic Svalbard triggered a trophic chain reaction, directly or indirectly affecting the demography of both overwintering and migratory vertebrates, ultimately inducing a shift in density-dependent phenotypic selection in migratory geese. A record-breaking rain-on-snow event and ice-locked pastures led to reindeer mass starvation and a population crash, followed by a period of low mortality and population recovery. This caused lagged, long-lasting reductions in reindeer carrion numbers and resultant low abundances of Arctic foxes, a scavenger on reindeer and predator of migratory birds. The associated decrease in Arctic fox predation of goose offspring allowed for a rapid increase in barnacle goose densities. As expected according to r- and K-selection theory, the goose body condition (affecting reproduction and post-fledging survival) maximising Malthusian fitness increased with this shift in population density. Thus, the winter ECE acting on reindeer and their scavenger, the Arctic fox, indirectly selected for higher body condition in migratory geese. This high Arctic study provides rare empirical evidence of links between ECEs, community dynamics and evolution, with implications for our understanding of indirect eco-evolutionary impacts of global change.

Ineffectiveness of plastic mesh for protecting artificial freshwater turtle nests from red fox (Vulpes vulpes) predation

AbstractInvasive mammalian predators are efficient at driving native animal declines. The red fox (Vulpes vulpes) kills millions of endemic reptiles in Australia each year. In areas of south‐eastern Australia, the eastern long‐necked turtle (Chelodina longicollis) and Murray River turtle (Emydura macquarii) have declined by more than 50%. High rates of nest predation by foxes limit the recruitment of young turtles in these populations, but previous methods of fox control have been ineffective at protecting turtle nests. Here, we tested the effectiveness of plastic mesh for protecting artificial turtle nests from predation by foxes, in the mid‐Murray catchment, Victoria. We also tested whether protecting a large number of artificial nests in a given area encourages foxes to give up foraging following predictions from giving‐up density theory. We made a series of plots, each containing 32 artificial turtle nests. In each plot, we covered a percentage (0%, 25%, 50%, 81% or 100%) of the nests with either 1 or 2 sheets of plastic mesh. We used remote cameras to photograph and identify any predator that attacked nests in the plots. The cameras also allowed us to estimate the amount of time a fox was visible on each plot, as a metric of how much effort foxes expended on protected nests. Nest survival rate was not increased by either 1 or 2 sheets of mesh, and increasing the number of protected nests on a plot did not reveal a giving‐up density (GUD) value for fox foraging behaviour. Our study demonstrates that plastic mesh is not effective for protecting artificial turtle nests from foxes in this region.

Nest traits and major flooding events influence nest survival of Emperor Geese while regional environmental variation linked to climate does not

Abstract The reproductive ecology of geese that breed in the Arctic and subarctic is likely susceptible to the effects of climate change, which is projected to alter the environmental conditions of northern latitudes. Nest survival is an important component of productivity in geese; however, the effects of regional environmental conditions on nest survival are not well understood for some species, including the Emperor Goose (Anser canagicus), a species of conservation concern that is endemic to the Bering Sea region. We estimated nest survival and examined how indices of regional environmental conditions, nest traits (nest age, initiation date, and maximum number of eggs in the nest), and researcher disturbance influenced daily survival probability (DSP) of Emperor Goose nests using hierarchical models and 24 years of nest monitoring data (1994–2017) from the Yukon–Kuskokwim Delta (Y–K Delta) in western Alaska. Our results indicate that overall nest survival was generally high (µ = 0.766, 95% CRI: 0.655–0.849) and ranged from 0.327 (95% CRI: 0.176–0.482) in 2013 to 0.905 (95% CRI: 0.839–0.953) in 1995. We found that DSPs of nests were influenced by nest traits, negatively influenced by major tidal flooding events and by researcher disturbance, but were not influenced by regional indices of spring timing, temperature and precipitation during nesting, or fox and vole abundance on the Y–K Delta. However, the number of nests found each year was negatively related to our index of fox abundance, suggesting nests that failed as a result of fox predation may have never been discovered due to our limited nest-searching efforts during egg laying. Our results suggest that regional environmental variation had minimal influence on the nest survival of Emperor Geese, although major flooding events were important. Nevertheless, we suspect that within-year variation in local weather conditions and local abundance of predators and alternative prey may be important and should be considered in future studies.

Modelling the recovery of resident shorebirds following a fox eradication program using citizen science data

Historically, the land-based threat to shorebird colonies on Phillip Island, Victoria, Australia, was fox predation. As a result, a fox eradication programme consisting of three phases: knock-down (i.e., 2006), clean-up (i.e., 2011), and post-eradication. In 2011 an effective knock-down was declared, signalling the beginning of the clean-up phase. The purpose of this research is to assess the recovery of six resident shorebird species on Phillip Island following fox removal. The statistical methodologies used are novel for assessing bird species population recovery following a successful predator eradication program. We used citizen science data from 2003 to 2017, extracted from the Atlas of Living Australia. The first analysis method used INLA modelling, which relied on a Negative Binomial distribution for bird counts to look for upward trends in shorebird populations during the fox eradication operation. The second method use changepoint analysis techniques to see whether successive phases of the eradication process were associated with changes in bird population numbers. Four of the six shorebird species investigated responded positively to reduced fox populations over the 15-year study, and all changepoint approaches consistently recognised the start of the clean-up phase, with less consistency identifying the start of the knock-down phase. Since 2006, the INLA models indicate a significant increase in the upward trend of shorebird populations for three of the six shorebird species investigated. Agreement across the four changepoint techniques indicates that changes in bird numbers were associated with the date of the eradication program's clean-up phase for all of these shorebird species. These results demonstrate some promise for these methods to monitor native species recovery during eradication programs.

Predation patterns on the tundra—genetic barcoding of scats from two sympatric fox species

In the Arctic tundra, climate-induced emergence of the red fox ( Vulpes vulpes (Linnaeus, 1758)), a competitor to the Arctic fox ( Vulpes lagopus (Linnaeus, 1758)), is predicted to influence predation patterns of both fox mesopredators. In this study, we (i) identified predator species from scats through an established barcoding approach and (ii) explored the use of a cheap, quick barcoding method of fox feces ( n = 103). We investigated differences in diet between the red fox (predicted generalist predator) and Arctic fox (predicted specialist predator) over 2 years with varying prey abundance. We amplified short DNA fragments (<200 bp) from small rodents, birds and hares. For both predators, there was a high frequency of occurrence of rodents (38%–69%) identifying them as primary prey species and birds as secondary prey species (13%–31%). This demonstrates the strength of a straightforward DNA barcoding method for dietary analyses in sympatric fox predators, with species-level resolution of prey. Barcoding is a promising tool for future dietary studies; however, a few methodological improvements, along with extended sampling, are needed for a more complete assessment of fox predation patterns. Integrating high-resolution dietary analyses have great potential to enhance our understanding of predation patterns in Arctic tundra communities.

Counting the bodies: Estimating the numbers and spatial variation of Australian reptiles, birds and mammals killed by two invasive mesopredators

AbstractAimIntroduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial.LocationAustralia.MethodsWe draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by (i) modelling continental‐scale spatial variation in fox density, (ii) modelling spatial variation in the frequency of occurrence of prey groups in fox diet, (iii) analysing the number of prey individuals within dietary samples and (iv) discounting animals taken as carrion. We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies.ResultsFoxes kill more reptiles, birds and mammals (peaking at 1071 km−2 year−1) than cats (55 km−2 year−1) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent – mainly the arid central and tropical northern regions (and on most Australian islands) – cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals.Main conclusionsThis continental‐scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia's poor contemporary conservation record.

Compounding and complementary carnivores: Australian bird species eaten by the introduced European red fox Vulpes vulpes and domestic cat Felis catus

Abstract Two introduced carnivores, the European red fox Vulpes vulpes and domestic cat Felis catus, have had extensive impacts on Australian biodiversity. In this study, we collate information on consumption of Australian birds by the fox, paralleling a recent study reporting on birds consumed by cats. We found records of consumption by foxes on 128 native bird species (18% of the non-vagrant bird fauna and 25% of those species within the fox’s range), a smaller tally than for cats (343 species, including 297 within the fox’s Australian range, a subset of that of the cat). Most (81%) bird species eaten by foxes are also eaten by cats, suggesting that predation impacts are compounded. As with consumption by cats, birds that nest or forage on the ground are most likely to be consumed by foxes. However, there is also some partitioning, with records of consumption by foxes but not cats for 25 bird species, indicating that impacts of the two predators may also be complementary. Bird species ≥3.4 kg were more likely to be eaten by foxes, and those <3.4 kg by cats. Our compilation provides an inventory and describes characteristics of Australian bird species known to be consumed by foxes, but we acknowledge that records of predation do not imply population-level impacts. Nonetheless, there is sufficient information from other studies to demonstrate that fox predation has significant impacts on the population viability of some Australian birds, especially larger birds, and those that nest or forage on the ground.

In the spotlight: Can lights be used to mitigate fox predation on a free-range piggery?

Across the world, the impact of livestock predation is a significant economic and welfare issue for producers, particularly for free-range farms. Non-lethal predator control methods have broad consumer appeal, but in most instances there has been little validation of their effectiveness. Predation remains a major limitation for outdoor piggeries, where predation is both an economic and welfare problem. We compared the efficacy of (1) no lighting (un-lit control), (2) commercially-available Foxlights®, and (3) motion-activated spotlights to test whether lights can deter red foxes (Vulpes vulpes) from approaching farrowing huts on an outdoor piggery breeding facility. Passive infrared camera traps were mounted at the entrance to the farrowing huts to monitor fox activity over 85 farrowings. Multiple incidences of foxes carrying piglets away from the huts (both dead and alive) were recorded. There were significant lighting treatment effects on fox activity (P = 0.031) and farm records for number of piglet births recorded per sow (P = 0.015). Compared with the un-lit control treatment, farrowing huts in the Foxlights® treatment had 12 % more fox activity, and 23 % fewer piglet births recorded for sows in these paddocks. Controlling for environmental covariates, there was predicted to be 39 % more fox activity on dark (new moon) nights for the Foxlights® treatment. By contrast, compared with the control, farrowing huts in the motion-activated spotlight treatment had similar overall fox activity (–5%) and piglet births recorded (–3 %). Interactions with moon phase (and rainfall as a prediction of cloud cover) are likely to be important considerations for studies of lighting deterrents, and we found that weaning rate (farm records for the proportion of piglets born alive that survived to weaning) was only influenced by lunar illumination (p = 0.003), with 16 % fewer piglets born around bright (full moon) nights surviving to weaning compared with dark (new moon) nights. Rather than being a deterrent, Foxlights® appear to be an attractant to foxes on this property, where there was no reinforcement with aversive human activity or other deterrent modalities. The motion-activated spotlights may be more effective because they are only activated when an animal is present and should therefore have reduced likelihood of habituation; however we found no data suggesting that they improved the outcome over our un-lit control treatment for this outdoor piggery.

Nest density and competing risks: A long-term investigation of Black Brant (Branta bernicla nigricans) nest survival

Many species of seabirds and waterfowl are predominantly colonial breeders, suggesting that colonial breeding is beneficial in some way. For Arctic nesting geese, colonial breeding may be an adaptive approach to minimize the risk of nest failure through predator swamping. Yet evidence for predator swamping is inconclusive. Species in low-lying coastal zones may have to manage tradeoffs between historical (e.g., predation) and increased frequency of other threats (e.g., coastal flooding associated with storm events). As the climate continues to change, coastal obligates will be subject to rising sea levels and an increase in extreme weather events, which could exacerbate the tradeoff between flooding and predation risk. We studied the effect of nest density on nest success in the colonial nesting Black Brant (Branta bernicla nigricans) on the Tutakoke River Colony in western Alaska and explored how density effects change during years of heavy Arctic fox (Alopex lagopus) predation and coastal flooding associated with storm events. We classified the colony as containing 2 strata that differed in elevation and vegetation, and were separated by the Tutakoke River. The stratum north of the Tutakoke River was 0.25 m lower in elevation and subject to periodic tidal flooding, while the southern stratum never flooded. Nest density positively affected brant nest success in years with high levels of fox predation. Nest success was greatest at the highest density during Normal years (low levels of fox predation and no flooding; northern stratum nest success 0.81 ± 0.01, southern stratum nest success 0.81 ± 0.01) and lowest in areas of low density during Fox years (northern stratum nest success 0.38 ± 0.01, southern stratum nest success 0.31 ± 0.01). Nest success was routinely higher during Normal years at all densities compared to Flood and Fox years. Our results support the hypothesis that colonial nesting, at least in tundra habitats, may have developed as a defense mechanism to swamp mammalian predators.

Reptiles as food: predation of Australian reptiles by introduced red foxes compounds and complements predation by cats

Context Invasive species are a major cause of biodiversity loss across much of the world, and a key threat to Australia’s diverse reptile fauna. There has been no previous comprehensive analysis of the potential impact of the introduced European red fox, Vulpes vulpes, on Australian reptiles. Aims We seek to provide an inventory of all Australian reptile species known to be consumed by the fox, and identify characteristics of squamate species associated with such predation. We also compare these tallies and characteristics with reptile species known to be consumed by the domestic cat, Felis catus, to examine whether predation by these two introduced species is compounded (i.e. affecting much the same set of species) or complementary (affecting different groups of species). Methods We collated records of Australian reptiles consumed by foxes in Australia, with most records deriving from fox dietary studies (tallying >35 000 samples). We modelled presence or absence of fox predation records against a set of biological and other traits, and population trends, for squamate species. Key results In total, 108 reptile species (~11% of Australia’s terrestrial reptile fauna) have been recorded as consumed by foxes, fewer than that reported for cats (263 species). Eighty-six species have been reported to be eaten by both predators. More Australian turtle species have been reported as consumed by foxes than by cats, including many that suffer high levels of predation on egg clutches. Twenty threatened reptile species have been reported as consumed by foxes, and 15 by cats. Squamate species consumed by foxes are more likely to be undergoing population decline than those not known to be consumed by foxes. The likelihood of predation by foxes increased with squamate species’ adult body mass, in contrast to the relationship for predation by cats, which peaked at ~217 g. Foxes, but not cats, were also less likely to consume venomous snakes. Conclusions The two introduced, and now widespread, predators have both compounding and complementary impacts on the Australian reptile fauna. Implications Enhanced and integrated management of the two introduced predators is likely to provide substantial conservation benefits to much of the Australian reptile fauna.

Eruptive dynamics are common in managed mammal populations.

Successful conservation management is often based on the principle that small or declining populations can recover if we identify and remove the factors that caused them to decline in the first place. But what form will that recovery take? Theory tells us that when a strong limiting factor is removed, a population should increase in size to where it becomes limited by some other factor. However, if the subsequent limitation involves feedbacks between the density of a consumer and its resource, there is potential for the consumer population to undergo substantial fluctuations in size that we would characterize as boom-bust or eruptive dynamics. We analysed long-term (7.6-29yr) data documenting changes in the abundance of 169 populations of 20 mammal species released from a strong limiting factor (fox predation) in Australia. We show that many populations (44) exhibited eruptive dynamics, with exponential increase to a peak and subsequent population decline. Of 51 populations showing eruptive dynamics (the Australian populations plus seven translocated ungulate populations), the time taken for erupting populations to reach a peak before declining was related negatively to the intrinsic rate of population growth and positively to body mass, such that larger-bodied species with slow rates of population growth had a longer period of population increase before declining. Our results suggest that a substantial proportion of populations recovering after removal of a threatening process are likely to exhibit eruptive dynamics, and that managers of recovering or translocated populations should anticipate this outcome in conservation planning.

Feeding behaviour of red fox and domestic cat populations in suburban areas in the south of Paris

Among medium-sized carnivores, red foxes (Vulpes vulpes) and domestic cats (Felis silvestris catus) are the most abundant species in human-dominated landscapes worldwide. Both are known to be generalist predators that exploit a wide range of prey groups (e.g., mammals, birds, and invertebrates). Identifying red fox and domestic cat predation pressure on shared prey could shed light on their ecological role in shaping wildlife communities in human-dominated landscapes. Here, we assess the seasonal diet of red foxes and domestic cats in terms of composition, breadth, and overlap. Over two years, we collected their scats across three human-dominated study sites: park (n = 220 for foxes and n = 0 for cats), agricultural land (n = 159 for foxes and n = 146 for cats), and managed forest (n = 169 for foxes and n = 47 for cats). We detected similar diet breadth (B) for red foxes and domestic cats (B = 0.32 and B = 0.36, respectively) as well as strong dietary overlap (O = 0.83) between them. Moreover, the diet composition of both predators varied according to the study sites and seasons. Our results confirm the highly flexible trophic behaviour of these carnivores at the study sites, probably as a consequence of prey availability, and also the simultaneity of their predation over the same prey groups. Future studies should simultaneously monitor predator diet as well as predator and prey abundance in human-dominated landscapes to better understand the predatory impact of red foxes and domestic cats.

Alien predation in wetlands – the Raccoon Dog and water birds breeding success

Alien predators are known to potentially strongly affect their prey populations. We studied the impact of raccoon dogs (Nyctereutes procyonoides) on waterbird breeding success in eight semi-urban wetlands in Finland. We manipulated raccoon dog density in two wetlands by removing individuals (2002 protection year, 2003 and 2004 removal years). We additionally performed nest predation experiments. We monitored raccoon dog density, estimated hunting bag size and observed waterbird breeding success. Our hypothesis predicts that the omnivorous raccoon dog plays a role in waterbird breeding success by depredating nests. Our experiments shown that the raccoon dog hunting bag in eutrophic wetlands may be large, as we removed 8.6–20.0 animals per km2. Both our nest predation experiment and field data indicated that raccoon dogs affect the breeding success of waterbirds. We found a significant relationship between raccoon dog density index and predation rate of the artificial nests, but not between red fox (Vulpes vulpes) density and predation on artificial nests. We did not find an association between raccoon dog abundance and the breeding success of mallards (Anas platyrhynchos) and great crested grebes (Podiceps cristatus). However, our study shows that birds species with different breeding strategies – e.g. great crested grebe, mute swan (Cygnus olor), mallard, Eurasian wigeon (Mareca penelope), coot (Fulica atra), lapwing (Vanellus vanellus) and marsh harrier (Circus aeruginosus) – when considered together showed higher breeding success both in 2003 and 2004 when compared to breeding success before removal. There was, however, variation in how strongly the species responded to raccoon dog removal. Our results indicate that the removal of alien raccoon dogs can be an important tool in wetland management.
 Keywords: ducks, invasive species, lapwing, nest predation experiment, Nyctereutes procyonoides, predator removal

Direct and indirect effects of regional and local climatic factors on trophic interactions in the Arctic tundra

Climate change can impact ecosystems by reshaping the dynamics of resource exploitation for predators and their prey. Alterations of these pathways could be especially intense in ecosystems characterized by a simple trophic structure and rapid warming trends, such as in the Arctic. However, quantifying the multiple direct and indirect pathways through which climate change is likely to alter trophic interactions and their relative strength remains a challenge. Here, we aim to identify direct and indirect causal mechanisms driven by climate affecting predator-prey interactions of species sharing a tundra food web. We based our study on relationships between one Arctic predator (Arctic fox) and its two main prey - lemmings (preferred prey) and snow geese (alternate prey) - which are exposed to variable local and regional climatic factors across years. We used a combination of models mapping multiple causal links among key variables derived from a long-term dataset (21years). We obtained several possible scenarios linking regional climate factors (Arctic oscillations) and local temperature and precipitation to the breeding of species. Our results suggest that both regional and local climate factors have direct and indirect impacts on the breeding of foxes and geese. Local climate showed a positive causal link with goose nesting success, while both regional and local climate displayed contrasted effects on the proportion of fox breeding. We found no impact of climate on lemming abundance. We observed positive relationships between lemming, fox and goose reproduction highlighting numerical and functional responses of fox to the variability of lemming abundance. Our study measures causal links and strength of interactions in a food web, quantifying both numerical response of a predator and apparent interactions between its two main prey. These results improve our understanding of the complex effects of climate on predator-prey interactions and our capacity to anticipate food web response to ongoing climate change.

Designing a camera trap monitoring program to measure efficacy of invasive predator management

Context Evaluating predator management efficacy is difficult, especially when resources are limited. Carefully designing monitoring programs in advance is critical for data collection that is sufficient to evaluate management success and to inform decisions. Aims The aim was to investigate how the design of camera trap studies can affect the ability to reliably detect changes in red fox (Vulpes vulpes) activity over space and time. Specifically, to examine the effect of study duration, camera cost and detection zone under various environmental and management scenarios, including different fox densities, management impacts, monitoring budgets and levels of spatial and temporal variation. Methods A generalised linear mixed model was used to analyse simulated datasets from control sites and sites with predator management actions implemented, following a before–after or control–impact sampling design. Statistical power analyses were conducted to evaluate whether a change in fox abundance could be detected across various environmental and management scenarios. Key results Results showed that a before–after sampling design is less sensitive than a control–impact sampling design to the number of cameras used for monitoring. However, a before–after sampling design requires a longer monitoring period to achieve a satisfactory level of power, due to higher sensitivity to study duration. Given a fixed budget, there can be a trade-off between purchasing a small number of high quality cameras with large detection zones, or a larger number of cameras with smaller detection zones. In a control-impact design we found that if spatial heterogeneity was high, a larger number of cameras with smaller detection zones provided more power to detect a difference in fox abundance. Conclusion This simulation-based approach demonstrates the importance of exploring various monitoring designs to detect the effect of predator management across plausible environmental and budgetary scenarios. Implications The present study informs the monitoring design of an adaptive management program that aims to understand the role of managing fox predation on malleefowl (Leipoa ocellata), a threatened Australian bird. Furthermore, this approach provides a useful guide for developing cost-effective camera trap monitoring studies to assess efficacy of conservation management programs. Power analyses are an essential step for designing efficient monitoring, and indicate the strength of ecological signals that can realistically be detected through the noise of spatial and temporal heterogeneity under various budgetary constraints.

First findings of brown hare (Lepus europaeus) reintroduction in relation to seasonal impact.

In Europe, brown hare (Lepus europaeus) populations have been declining steadily since the 1970s. Gamekeepers can help to support brown hare wild populations by releasing cage-reared hares into the wild. Survival rates of cage-reared hares has been investigated in previous studies, however, survival times in relation to seasonality, which likely plays a crucial role for the efficacy of this management strategy, has not been evaluated. Here we examine the survival duration and daytime home ranges of 22 hares released and radio-tracked during different periods of the year in East Bohemia, Czech Republic. The majority of hares (82%) died within the first six months after release, and 41% individuals died within the first 10 days. Significant differences were found in the duration of survival with respect to the release date. Hares released in the summer months (July and August) survived the longest (on average 103.2 days, SD ± 23.8) and hares released throughout all other months of the year survived for significantly shorter periods of time (on average 20.4 days, SD ± 11.5). The most likely cause of death was red fox predation (38.9%) followed by disease (coccidiosis and other health problems) (27.8%). Three hares (16.6%) were killed by automobile traffic. After six months of radiotracking, we found the average survival time of all hares released was 58 (SD ± 70.9) days. Hares in this study preferred to remain in the vicinity of the release area and the average distance from release point to the center of the home range was 471 m.