Distribution Of Foxes Research Articles

Predicted future range expansion of a small carnivore: swift fox in North America

ContextSmall carnivores are declining globally due to a complex suite of threats. Conservation of these species requires an understanding of their distributions and potential responses to future land-use and climate change.ObjectivesWe modelled species-environment relationships of swift fox (Vulpes velox), a species of concern across their range. We developed spatial projections of current and future distribution to aid in conservation planning.MethodsWe assembled swift fox occurrence data from managers and community science sources to develop ensemble distribution models. In addition to landscape and climatic predictors, we developed a model of red fox distribution to represent effects of competition. We forecasted spatial predictions into the year 2070 under two climate change scenarios representing high (SSP 5–8.5) and low (SSP 1–2.6) emissions scenarios.ResultsPercent cover by grassland, mean annual precipitation, and minimum temperature of the coldest quarter were the three most important variables for swift fox distribution. Current suitable habitat for swift fox extends across 16 North American states and provinces. Future projections of swift fox distribution suggest an overall increase in area of swift fox suitable habitat under both emissions scenarios of > 56.9%, though patterns of gain and loss vary spatially.ConclusionsThe expansion of suitable habitat in future scenarios reflects swift fox adaptability to multiple land uses in a period following multi-organizational conservation efforts. Our spatial projections can be used in conservation planning and can serve as a case study of a small carnivore species likely to recover under future change scenarios provided that threats are addressed and landscape-scale conservation efforts continue.

Rabies and the Arctic Fox (Vulpes lagopus): A Review.

The Arctic fox (Vulpes lagopus) is the primary infection reservoir of Arctic rabies, the dynamics of which are poorly understood and subject to significant spatiotemporal variation. Although rabies presence has been documented in the region since the mid-19th century, there is currently no evidence of rabies impacting Arctic fox population size. Under the influence of climate change in a rapidly evolving Arctic ecosystem, alterations in transmission dynamics are predicted, with implications for this species. Concurrently, the World Health Organization leads the United Against Rabies collective in the aim of elimination of dog-mediated rabies by 2030, and although efforts have justifiably been directed to tropical regions, elimination will require a good understanding of rabies in the Arctic. Therefore, this review aimed to provide an overview of current Arctic rabies understanding, while identifying the key knowledge gaps. The review covered spatiotemporal trends in rabies populations, population dynamics of the host species, and current theories about Arctic rabies persistence. It is still unclear how Arctic rabies can persist under low host densities, which has led to several hypotheses in recent years. Creation of high animal density "hotspots" caused by heterogenic fox distribution and multispecies congregations in response to food availability, extensive Arctic fox migration patterns, and the potential evolution to a less lethal variant of rabies may all be part of the explanation. Evidence for these theories by using recent genetic and modeling studies was evaluated within the review. There is currently insufficient evidence about the efficacy and feasibility of vaccines against Arctic rabies. Key knowledge gaps need addressing to enable future control campaigns.

The pulsed effects of reintroducing wolves on the carnivore community of Isle Royale

Large carnivores are being globally reintroduced with the goal of restoring ecological interactions. However, the extent that competitive interactions are restored within communities is often unclear. In a before–after study within Isle Royale National Park (in the US state of Michigan), we quantified the spatial, behavioral, trophic, and demographic effects of the reintroduction of a large carnivore (gray wolf; Canis lupus) on meso‐carnivores (red fox; Vulpes vulpes) and small carnivores (American marten; Martes americana). The wolf reintroduction produced a phase‐dependent pulse perturbation: wolves constrained the distribution of foxes, thereby benefiting martens, yet foxes altered their behavior, notably using human‐provided resource subsidies (campsites and food) more frequently, which buffered demographic consequences. Once wolf packs coalesced, all observed changes subsided, and competitive interactions returned to their pre‐wolf values. Our results show that some predicted—and often desired—consequences of large carnivore reintroductions may not be permanent due to the transitory dynamics of social carnivores and the presence of humans, even within a “pristine wilderness”.

Phase‐dependent red fox expansion into the tundra: implications for management

AbstractExpansion of boreal species into tundra ecosystems is a consequence of climate change and human exploitation that threatens local species through increased predation, competition, and pathogen transmission. Under these circumstances, efficient control of expanding boreal species may be necessary, but the efficiency of such action depends on understanding the ecological influences of expansion. The red fox (Vulpes vulpes) is expanding into the tundra across the Arctic. In Scandinavia, red foxes threaten local tundra species and communities including the endangered Arctic fox (V. lagopus). The ecological dynamics in the tundra are influenced by small rodent cycles (classified into different phases based on seasonal abundance fluctuations), which can affect red fox expansion, distribution, and abundance. We used a 17‐year (2004–2020) dataset from the tundra in Sweden, consisting of raw snow track data, to test how cyclic prey influenced red fox distribution and abundance, and subsequently red fox control. The winter abundance of red fox was influenced by small rodent phase, with higher abundance during high prey availability (i.e., increased number of prey numbers) with no support for a time lag between red fox and small rodent abundance. This suggests that high prey availability attracts red foxes to the tundra and that higher immigration from the boreal zone can be expected in response to increased prey abundances. There was no relationship between red fox control and small rodent availability, but control was influenced by red fox abundance during the previous year, which highlights an opportunistic control strategy. We recommend an adaptive management strategy where authorities include small rodent dynamics in the planning and execution of red fox control.

Fox control and fire influence the occurrence of invasive predators and threatened native prey

AbstractIt can be challenging to distinguish management impacts from other population drivers, including ‘natural’ processes and co-occurring threats. However, disentangling processes is important, particularly when management may have unintended consequences, such as mesopredator release. We explored the effects of long-term, broadscale poison-baiting programs on the distribution of red foxes Vulpes vulpes (targeted invasive predator), feral cats Felis catus (unmanaged invasive competitor) and two of their threatened native prey in two fire-affected regions of south-eastern Australia. We synthesised data from 3667 camera-trap deployments at 1232 sites (172,052 trap-nights), combining experimental manipulation of foxes and fire with space-for-time approaches. Fox control effectiveness—in terms of decreased probability of fox occurrence and increased probability of prey occurrence—depended on the duration and intensity of the poison-baiting program. The effects of fox control on prey occurrence also varied between the two native prey species: fox control was strongly beneficial to the long-nosed potoroo Potorous tridactylus but had no measurable effect on southern brown bandicoot Isoodon obesulus occurrence. Feral cat occupancy tended to be higher in landscapes with long-term fox control, although we found no effect of fox-bait density on fine-scale cat occurrence. Time since fire (0–80 years) was associated with the occurrence of each study species, but its association with invasive predators also differed among vegetation types. Invasive predators and altered fire regimes are key, often overlapping, biodiversity threats. Our work highlights the importance of fine-scale monitoring and consideration of multiple drivers in distribution models to develop effective, tailored conservation strategies.

Arctic and red fox population responses to climate and cryosphere changes at the Arctic's edge.

Responses of one species to climate change may influence the population dynamics of others, particularly in the Arctic where food webs are strongly linked. Specifically, changes to the cryosphere may limit prey availability for predators. We examined Arctic (Vulpes lagopus) and red fox (V. vulpes) population dynamics near the southern edge of the Arctic fox distribution using fur harvest records from Churchill, Manitoba, Canada between 1955 and 2012. Arctic foxes showed a declining population trend over time (inferred from harvest records corrected for trapping effort), whereas the red fox population trend was relatively stable. The positive relationship between the annual Arctic and red fox harvests suggested interspecific competition did not promote the Arctic fox decline. To investigate alternative mechanisms, we evaluated the relative influence of sea-ice phenology, snow depth, snow duration, winter thaws, and summer temperature on the harvest dynamics of both species in the most recent 32years (1980-2012; n = 29) of our data. Arctic fox harvests were negatively related to the length of time Hudson Bay was free of sea ice. Shorter sea ice duration may reduce access to seal carrion as an alternative winter food source when lemming densities decline. Contrary to our prediction, red fox harvest was not related to summer temperature but was positively related to snow depth, suggesting winter prey availability may limit red fox population growth. Predators have an important ecological role, so understanding the influence of changes in the cryosphere on predator-prey interactions may better illuminate the broader influence of climate change on food-web dynamics.

Carnivore coexistence in Chicago: niche partitioning of coyotes and red foxes

Mesopredators including coyotes (Canis latrans) and red foxes (Vulpes vulpes) often co-occur in urban environments, but how niche partitioning facilitates their coexistence remains unclear. Highly urbanized areas can be spatial refuges for smaller mesopredators (i.e., spatial human shield effect), however these species also may coexist through temporal niche partitioning. We used camera traps (n = 110 sites) across an urbanization gradient in Chicago to examine coyote-fox interactions from 2011 to 2018. We analyzed spatial partitioning through multi-season occupancy models and structural equation modeling (SEM), and quantified temporal overlap between canids and with humans. Coyotes most often occurred in natural areas, and urbanization reduced their colonization rates and increased their extinction rates. Initial occupancy for red foxes was negatively impacted by urbanization, but their extinction rates depended on a surprising interaction between coyotes and humans. When coyotes were rare, fox extinction was related positively to human activity; but when coyotes were more common, fox extinction was related negatively to human activity. This outcome may reflect a human shield effect at a within-site scale. The SEM further supported the negative impact of urbanization on both canids, and lack of an effect of coyotes on the distribution of foxes. Diel activity of coyotes and red foxes indicated temporal niche partitioning intensified at more urbanized sites. Our results suggest the spatial human shield effect is not operating across sites in Chicago. Instead, coyotes and red foxes may share green spaces, especially in highly urbanized areas, where species coexistence is promoted by temporal niche partitioning.

Rabies transmission in the Arctic: An agent-based model reveals the effects of broad-scale movement strategies on contact risk between Arctic foxes

Arctic rabies is an ongoing threat to human populations and domestic animals inpolar regions, where Arctic foxes (Vulpes lagopus) are the main reservoir hosts. Human-driven changes in resource availability are shifting the distribution of Arctic foxes and these changes may affect the risk of rabies transmission and spread. Our understanding of the effects of broad-scale movement strategies in Arctic foxes and spatial distribution of resources on contact patterns among Arctic foxes, and their consequences on the dynamics of rabies epidemiology remains limited, in part, due to the difficulty of obtaining contact data from such remote and expansive regions. In this perspective, we built a spatially explicit agent-based model coupled with hidden Markov models to explore how Arctic fox movement behavior, combined with Arctic fox population density, resource availability and rabies transmission dynamics, affects the risk of infectious contact between Arctic foxes across heterogeneous landscapes. The model was parameterized using a combination of unique field data collected in the Canadian High Arctic and published studies from other Arctic regions. A sensitivity analysis was performed to assess the effects of multiple model input parameters on contact rates among Arctic foxes. Our results showed that cumulative contact rates per fox were driven by predictors related to rabies transmission dynamics and fox carrying capacity, while unique contact rates per fox and unique infectious contact rates per rabid fox were best predicted by parameters associated with rabies transmission dynamics, fox movement behavior, and fox carrying capacity. Ultimately, our study provides new insights into the ecological drivers of rabies transmission and may inspire further research on modelling cost-effective rabies prevention strategies in the Arctic.

Is time partitioning the currency of coexistence for a grassland canid community?

Habitat and diet preferences are often considered major aspects of niches differentiation among species; however, partitioning of habitat and resource use temporally is often overlooked in modeling coexistence. The plasticity of temporal activity patterns of individuals may influence the species' response to selective forces and long‐term persistence. Temporal avoidance may be a mechanism by which subordinate species can reduce the likelihood of direct competition with dominant sympatric species. Here, we examine temporal activity patterns of three canid species (swift fox Vulpes velox, red fox Vulpes vulpes and coyote Canis latrans) to determine how temporal activity patterns and activity overlap varies among species. We found that all species presented seasonal differences in activity patterns. When activity patterns were compared among species, the estimates of activity overlap in the spring season (i.e. breeding and pup‐rearing periods) were higher than the activity patterns in the fall (i.e. juvenile dispersal and pair‐formation periods); however, activity pattern overlap among species was significant only during the fall. Overall, these patterns revealed a close temporal overlap between swift fox (subordinate species) and both red fox and coyote (dominant species), which provides insight into conditions under which time partitioning may not be as clear as predicted, and other mechanisms may facilitate species coexistence. Considering swift fox population decline and distribution contraction across the North American grasslands, investigating temporal activity patterns of the canid species may reveal the implications of altering such patterns for individual animals, populations and ecosystems.

Modelling the distribution and intraguild associations of an understudied mesocarnivore across the contiguous United States

AbstractAimUnderstanding the range‐wide distribution and abundance of species is critical for their conservation and management. Grey foxes (Urocyon cinereoargenteus) are an understudied, low‐density mesocarnivore with a broad geographic range. However, the factors that underlie this broad distribution are poorly understood and large‐scale analyses of this species’ range and ecological niche are lacking.LocationWe modelled the probability and intensity of site use for grey foxes at two spatial scales using a coordinated survey of 1485 camera traps across the contiguous United States in 2019.MethodsWe used Bayesian occupancy modelling and post hoc species interaction comparisons to evaluate factors hypothesized to affect grey fox site use, including habitat, anthropogenic effects, and intraguild interactions.ResultsOur results showed that the presence of bobcats (Lynx rufus) and striped skunks (Mephitis mephitis), as well as forest variables, had positive associations with grey fox site use. Surprisingly, we found no support for negative effects on grey fox space use from dominant competitors (coyotes, Canis latrans, or pumas, Puma concolor), and a complete lack of effects from urbanization metrics and gross primary productivity. We did, however, find a consistent negative association with red foxes (Vulpes vulpes), which is the most ecologically and morphologically similar competitor of grey foxes.Main conclusionsTaken together, these results imply that grey fox distribution is not limited by dominant carnivores or anthropogenic pressure. Rather, this species seems to occupy a unique niche across its broad range by exploiting diverse forest habitats shared with less ecologically similar competitors (striped skunks and raccoons, Procyon lotor), while being somewhat limited by a competitor occupying a similar ecological niche (red foxes). Our study highlights the value of broad‐scale approaches for evaluating factors influencing the distribution and abundance of understudied species, as local dynamics might fail to manifest across geographic ranges.

Canine Circovirus in Foxes from Northern Italy: Where Did It All Begin?

Canine circovirus (CanineCV) is a recently identified virus affecting both domestic and wild carnivores, including foxes, sometimes in presence of severe clinical signs. Its circulation in wild animals can thus represent a potential threat for endangered species conservation and an infection source for dogs. Nevertheless, no data were available on its circulation in the Alps region of Northern Italy. In the present study, samples collected from 186 foxes in the period 2009–2020 from Valle d’Aosta and Veneto regions were tested using a real-time PCR assay, demonstrating a viral circulation of approximatively 2–5%, depending on the considered regions. Two complete or almost complete genome sequences were obtained, highlighting that the detected strains were part of a so defined “fox only” clade, which suggests that, despite common contact opportunities, Alps foxes are not involved in frequent transmission events to domestic dogs. Such genetic isolation could be at least partially attributed to some sort of independent evolution occurred in the foxes, leading to species barrier. Additionally, CanineCV strains in foxes from Italy were unexpectedly related to those previously identified in foxes from the United Kingdom and Scandinavian area. Combining the history of fox distribution in Europe since the last glacial maximum (LGM) with the viral history allowed us to speculate a long-standing coexistence between European canine circovirus and this host, justifying the peculiar geographic distribution and evolutionary paths of the fox infecting clade.

Colonization of Warsaw by the red fox Vulpes vulpes in the years 1976\u20132019

The red fox is one of the most adaptable carnivores inhabiting cities. The aim of our study was to describe the process of Warsaw colonization by the red fox. We focused on: (1) the fox distribution in Warsaw on the basis of presence-absence data (2005–2012) over a grid of 1 × 1 km2, (2) the process of settlement in 29 green areas (study periods 1976–1978, 2004–2012, and 2016–2019) in relation to habitat type, and (3) temporal and spatial patterns of the red fox incidents (1998–2015) reported by Warsaw citizens. We found out that: (1) the red fox penetrated the whole city (i.e. its presence was confirmed in all squares of the grid), (2) 21% of the green areas were colonized in 1976–1978 but 93% in 2016–2019. Forests and riparian habitats were occupied more frequently than parks and cemeteries in 1976–1978 with no difference in the further years; (3) the probability of the fox incidents increased over years, was higher in June-October, on working days, and around noon, and with the share of discontinuous urban fabric in the buffers around incident locations. Nevertheless, the incidents only partially reflect population abundance trends and activity patterns of the species, so should be treated cautiously.

Combining cameras and citizen science to define the distribution and behaviour of dingoes and foxes in New South Wales

We used two survey methods - citizen science for private land and cameras for protected areas - to map the distribution of dingoes/wild dogs and foxes in NSW. Dingo/wild dog records were mostly confined to the east coast and ranges, with scattered locations in western NSW. This contrasts to the distribution of foxes, in which occupancy was high across most of the state. Data from 200 WildCount camera sites within protected areas also showed marked differences in the distribution of the two canid species. At the scale of the state, dingoes/wild dogs are uncommon, with the greatest concentration being in the north-east of the state, as well as a marked presence in the south-east. Foxes are common and widespread within protected areas, but less common in the north-east of the state. The camera data also indicated that feral cats are widespread within protected areas. The second aim of our study was to examine the WildCount data for behavioural patterns of the canid species. Foxes and dingoes/wild dogs significantly separated within two sub-formations of dry sclerophyll forest based on the Keith (2004) classification of NSW vegetation. From species pairwise interactions at sites, we found only limited evidence for significant interactions, and then only for the co-occurrence of fox-rabbit and fox-swamp wallaby, but no avoidance for any of the predators with each other. Camera records of the time of day of being active showed little effect of the presence of dingoes/wild dogs on the times of activity of foxes, but foxes curtailed the activity times of dingoes/wild dogs. From the analysis of inter-animal times at sites where both canids were recorded, there was little difference between the time since the other species was present. Thus, there was no evidence that dingoes/wild dogs or foxes inhibit the other from being at a site. We concluded that at the landscape level, both vegetation type and land tenure play a role in the interactions between dingoes/wild dogs and foxes. We also concluded that citizen science and cameras are complementary, not alternative techniques, especially as they sample different land tenures, and that cameras in protected areas and occupancy from citizen science have produced higher resolution maps and behaviour patterns than have been previously available. We can confirm that foxes are a ubiquitous threat throughout NSW, whereas dingoes/wild dogs are concentrated into a much smaller area of eastern, particularly north-eastern, NSW.

The impact of human land use and landscape productivity on population dynamics of red fox in southeastern Norway

In the boreal forest, the red fox (Vulpes vulpes) is a key species due to its many strong food web linkages and its exploitation of niches that form in the wake of human activities. Recent altitudinal range expansion and a perceived population increase have become topics of concern in Scandinavia, primarily due to the potential impacts of red foxes on both prey and competitor species. However, despite it being a common species, there is still surprisingly little knowledge about the temporal and spatial characteristics of its population dynamics. In this study, we synthesized 12 years of snow-track transect data covering a 27,000-km2 study area to identify factors associated with red fox distribution and population dynamics. Using Bayesian hierarchical regression models, we evaluated the relationships of landscape productivity and climate gradients as well as anthropogenic subsidies with an index of red fox population size and growth rates. We found that landscapes with high human settlement density and large amounts of gut piles from moose (Alces alces) hunting were associated with higher red fox abundances. Population dynamics were characterized by direct density-dependent growth, and the structure of density dependence was best explained by the amount of agricultural land in the landscape. Population equilibrium levels increased, and populations were more stable, in areas with a higher presence of agricultural lands, whereas density-dependent population growth was more prominent in areas of low agricultural presence. We conclude that human land use is a dominant driver of red fox population dynamics in the boreal forest. We encourage further research focusing on contrasting effects of anthropogenic subsidization on predator population carrying capacities and temporal stability, and potential impacts on prey dynamics.

Spatial distribution of sarcoptic mange (Sarcoptes scabiei) in urban foxes (Vulpes vulpes) in Great Britain as determined by citizen science

Urban areas may support high densities of wild carnivores, and pathogens can strongly influence carnivore populations. Red foxes (Vulpes vulpes) are hosts of sarcoptic mange (Sarcoptes scabiei), which infects numerous species, and transmission can be density dependent. In Great Britain, urban red foxes (Vulpes vulpes) have recently increased in population density and undergone range expansions. Here we investigate corresponding changes in urban fox mange prevalence. We predicted a higher prevalence closer to historic epi/enzootics and lower prevalence where urban features reduce fox density and movements, i.e. large areas of public green space, and fragmented habitat, as measured by road length and urban perimeter shape complexity. We visually assessed mange symptoms from georeferenced images of urban foxes submitted online by the public, thus surveying private land on a national scale. We measured the proportion of foxes apparently showing mange and used SATSCAN to identify spatial clusters of high infection risk. Landscape features were extracted from urban layers in GIS to determine associations. Although mange was widespread, we identified a single cluster of high prevalence (37.1%) in Northwest and Central England, which exceeded double mean prevalence overall (15.1%) and mirrors the northward expansion of urban fox distribution. Prevalence was positively correlated with perimeter shape complexity and negatively correlated with distance to the nearest city with mange, although the latter association was weak. Our findings show that citizen science can effectively monitor diseases with highly visible symptoms and suggest that fox movements are influential in explaining spatial patterns of prevalence.

Distribution, fine-scale subdivision, and population size of San Joaquin kit foxes in the Ciervo-Panoche Natural Area, California

The endangered San Joaquin kit fox (SJKF; Vulpes macrotis mutica) is strongly linked ecologically to xeric areas with high abundance of kangaroo rats. Endemic to the San Joaquin Desert of central California, the elusive nature of SJKF, coupled with steady habitat loss and lack of comprehensive surveys, has precluded efforts to quantify the species’ population size and distribution, especially in the central and northern parts of its range. Because the Ciervo-Panoche Natural Area contains the largest area of high-quality habitat in this central/northern region, we conducted systematic transect surveys for SJKF scats with professionally trained dog-handler teams throughout the area during 2009–2011. We collected almost 600 scats over 473 km of transects, documenting the freshness and location of each scat. Using molecular methods, we identified 93 SJKF individuals (56 males and 37 females) from 332 samples. Half of the individuals carried a mtDNA haplotype with a 16 bp deletion that had not been previously detected in other areas surveyed. Four individuals were recaptured in 2010 and five in 2011, including one female that was captured every year. We documented a unique mtDNA haplotype and more individuals across a wider area of the Ciervo-Panoche Natural Area than expected. Population analyses revealed two distinct subpopulations, with low connectivity between foxes in the Panoche Valley that are separated by hills with unsuitable habitat from those on the adjacent valley floor next to a major Interstate highway (I-5). While individuals detected within 6 km of each other were closely related, overall relatedness within each subpopulation approached zero. Genetic population models indicated a conservative population estimate of 90 kit foxes in total, with 60–90 individuals in the Panoche Valley and 17–27 individuals in the I-5 area. These results will help to inform management of the SJKF and identify areas that may be important to maintaining connectivity between populations.

Occupancy, habitat, and abundance of the Sacramento Valley red fox

ABSTRACTThe Sacramento Valley red fox (Vulpes vulpes patwin) is a native subspecies of conservation need endemic to the northern portion of California's Central Valley, USA. We conducted an occupancy survey to investigate habitat use and obtain a crude, range‐wide estimate of abundance. We used 2 previously developed red fox distribution models based on presence‐only data to stratify sampling of 107 sites with baited cameras for ≥90 days during March 2013–June 2016, resulting in red fox detections at 30 sites. All detections occurred in 1 of the 93 sites where 1 or both previous presence‐only models predicted occurrence. Red fox occurrence was positively associated with dry agriculture, human development, and proximity to grassland, and negatively associated with wetlands and flooded agriculture. The models predicted that 34.21% of the 12,000‐km2 Sacramento Valley landscape contained red foxes, which we estimate corresponded to approximately 1,600 breeding individuals. This estimate is comparable to that of the federally endangered California San Joaquin kit fox (Vulpes macrotis mutica), underscoring its potential vulnerability and conservation need. Targeted efforts to enhance its habitat, such as juxtaposition of grassland patches with agricultural and rural residential structures through conservation easements, could benefit conservation of the Sacramento Valley red fox. © 2018 The Wildlife Society.

GIS-based environmental analysis of fox and canine lungworm distribution: an epidemiological study of Angiostrongylus vasorum and Crenosoma vulpis in red foxes from Slovakia.

Over a period of intervening years, the distribution of two canine cardiopulmonary metastrongylid nematodes, Angiostrongylus vasorum and Crenosoma vulpis, has been recognised in Central Europe. Here, we report the first epidemiological research conducted in red foxes from Slovakia and the potential influence of selected environmental variables on the parasites' occurrence, quantified by logistic regression. The environmental models revealed that distribution of C. vulpis is not significantly influenced by any environmental variables, and the parasite is present in the whole area under study. Models for A. vasorum revealed some weak influence of environmental variables, as it tends to occur in drier areas with lower proportion of forest. Moreover, A. vasorum shows a typical spatial clustering and occurs in endemic foci identified mainly in the eastern part of Slovakia. A cluster of A. vasorum infection foci was also found in the north-eastern region, where the average winter air temperature regularly falls below - 10°C.

Record and distribution of black-fur foxes in a Mediterranean natural park, Serra de Mariola, Spain

This research was funded partially by the Conselleria de Educacion y Cultura grant GVA-PRE/2008/036, and the Conselleria de Medio Ambiente, Agua, Urbanismo y Vivienda grant T6217-2010 from the Valencian regional government, and the Instituto Alicantino de Cultura Juan Gil-Albert research grant 2008.

Microtus arvalis and Arvicola scherman: Key Players in the Echinococcus multilocularis Life Cycle.

A broad range of rodent species are described as potential intermediate hosts for Echinococcus multilocularis, a wide-spread zoonotic cestode causing alveolar echinococcosis. However, little is known about the relative contribution of these species for parasite reproduction and the maintenance of its life cycle. In a comparative study in a high endemic region in Zurich, Switzerland, we investigated prevalence rates and fertility of E. multilocularis in the most abundant vole species as well as the predation rate of foxes on these species. To ensure that the fox families had access to different vole species and that these voles were exposed to the same environmental contamination with parasite eggs, we selected eight study plots where at least two rodent species co-occurred. The parasite prevalence in Microtus arvalis [11.0%, confidence intervals (CI) 8.9–13.4] was significantly higher than in Arvicola scherman (5.3%, 3.9–7.1) and Myodes glareolus (3.9%, 2.0–6.7). None of the, only 29 individuals of, Microtus agrestis was infected (0%, 0.0–9.8) and the species was excluded for further analyses. Logistic regression models for the prevalences revealed significant differences between nearby study plots and higher infection rates for females, heavier individuals, and individuals trapped during spring, when the prevalence in M. arvalis peaked up to 65% (CI 50–79) in one plot. Furthermore, we detected significantly higher percentages of fertile infections in M. arvalis and M. glareolus than in A. scherman (OR 11.2 and 6.4, respectively) and a significantly higher protoscolex number in M. glareolus (median 100,000) than in M. arvalis (13,500) and A. scherman (4,290). The most abundant fox prey remains were of the genera Microtus (12.3%, CI 8.4–17.2) and Arvicola (11.5%, 7.7–16.3), whereas Myodes was never recorded as prey (0.0–1.3%). We conclude that M. arvalis and to a lesser extent A. scherman can be regarded as key intermediate hosts in Western and Central European high-endemic regions whereas M. glareolus and M. agrestis play a marginal role. We, therefore, postulate that distribution models of these species could contribute to predict parasite occurrence on a more detailed spatial scale than models of the distribution of foxes which have a very broad and uniform distribution.