Fox Density Research Articles

Influence of ground predators and water levels on Lapwing Vanellus vanellus breeding success in two continental wetlands

Insufficient productivity has driven population declines in grassland breeding waders with high levels of predation limiting productivity in many wetland reserves. We studied hatching and fledging success of Lapwings Vanellus vanellus in two continental river floodplains (Havel and Oder) differing in water regime and density of Red Foxes Vulpes vulpes to assess the effects of increased water tables as a management option. Nest predation rates were high on dry sites as well as on flooded grasslands in all areas irrespective of fox litter density. Carnivores formed the majority of the predators identified and eggshell remains suggested that mustelids took proportionally more nests at low fox densities. At unsuccessful nests on flooded grassland, an increasing incidence of nocturnal disturbances prior to predation indicated an influx of carnivores as the sites dried out. Brood survival depended on the availability of wet features, and productivity was thus linked to water tables in June in one area (Havel). Productivity was insufficient to maintain local populations in all areas and years except for two occasions related to increased water tables. Retaining high water tables throughout the breeding season therefore remains an important management option for waders on continental wet grasslands.

Changes in the density and spatial distribution of red fox dens and cub numbers in central Poland following rabies vaccination

Increases in red foxVulpes vulpes (Linnaeus, 1758) numbers and densities have been found in all European countries involved in the rabies vaccination program. In Poland, the number of foxes has increased steadily since the 1990s. Between 1999–2000, the average density of foxes reached 1.3–2 ind./km2 in some parts of the country. The aim of the study was to estimate the change in fox population densities in central Poland during 1980–2006, and to assess the effect these changes have had on the spatial distribution of natal dens, mean numbers of cubs observed at occupied dens and the sedentary/nomadic fox ratio. Estimations of fox population density and numbers were based on three methods: (1) counts of tracks in snow, (2) locations of natal dens and counts of cubs, and (3) the battue (driving) method. The three methods of assessment were used continuously in our study area over a period of 25 years. Average yearly results were analysed and comparisons made between the periods before and after implementation of the anti-rabies vaccination. The results obtained with all three methods show a significant increase in the fox population, when the two analysed periods are compared. Increases in fox population densities correlated with increased numbers of breeding sites being located outside forests, from only single ones in the 1980s to 24% of the total in 2005. The average number of cubs per occupied den decreased significantly (by 11%) in comparison with before the anti-rabies vaccination period. The great increase (more than 100%) in fox numbers observed using the battue (driving) method suggest, that nomadic animals can form an important part of winter population in our study area.

Predation of Lapwing Vanellus vanellus nests on lowland wet grassland in England and Wales: effects of nest density, habitat and predator abundance

There is concern that predation of Lapwing Vanellus vanellus nests may create additional pressure on declining populations of this species in Europe. At seven sites in England and Wales, daily nest predation rates on 1,390 nests were related to variables using Generalised Linear Mixed Models. The strongest predictor was Lapwing nest density (number of nests within 100 m): predation rates declined as nest density increased. Since nocturnal species, probably mammals, have been identified as the major predators of Lapwing nests at these sites, these results suggest that Lapwings are able to deter mammalian predators or may settle to nest at high densities in areas with low predation pressure. At the site level, there was no relationship between Lapwing nesting density and fox density, and a positive relationship with Carrion Crow Corvus corone nesting density. There was a weaker effect of distance to field boundary: nests closer to boundaries were more likely to be predated. Weak interactive effects between crow density and both nest visibility and distance to vantage point were identified in models using a reduced subset of nests. These were counter-intuitive, did not persist in the larger data set, and do not have obvious explanations. If Lapwings nesting at high density are able to deter predators, there are implications for land management. Smaller areas could be managed within potential breeding habitat to encourage Lapwings to nest in dense colonies. Selection of larger fields for such management, where nests could be located far from the field boundary should improve the value of such measures.

Does agriculture drive predator‐mediated behavioral effects on prey?

Agriculture may create or destroy habitat for native species, and some species may do better when land is converted to agricultural uses. For instance, populations of human commensals, such as rats, and some predators, such as foxes, may increase following agricultural land conversion. Shapira, Sultan & Shanas (2008) capitalized on the apparent agriculturally induced increase in red fox populations to study the behavioral decisions made by two species of gerbils. Their ‘natural experiment’ was conducted along the border between Israel and Jordan in the arid Arava desert ecosystem. On the Jordanian side, pastoralists and traditional farmers live and work in the arid landscape. On the Israeli side, modern, irrigated, agricultural farms fill the land. As the authors first assumed, and then tried to verify with track counts, red fox density was higher on the Israeli agricultural lands than on the Jordanian side of the border. The authors designed a ‘giving-up-density’ experiment – a method widely used by behavioral ecologists to study risk assessment (Brown, 1999). Gerbils visiting trays containing a fixed quantity of seeds mixed with sand would forage until they assessed the marginal benefits of remaining at the trays to begin to decline. We assume the decision to leave a tray is a function of both the amount of food in the tray (presumably assessed by the harvest rate), and predation risk. Assuming that gerbils would not want to spend more time foraging for less food, the amount of food they leave (the giving-up density) reflects the gerbil’s assessment of risk. Shapira, Sultan and Shanas put these trays with a fixed amount of food in close to and far from cover near and 6 km away from Israeli farms in the more rustic Jordanian landscape. They also conducted these experiments on full-moon nights and nights without moonlight because many small prey (including gerbils) are sensitive the greater risk associated with foraging when the moon is out. Gerbils left more food on full-moon nights than on moonless nights, but there was no effect of distance to cover on giving-up density. They then conducted a more complex experiment where they created trays with diminishing returns by putting lower densities of food at a lower level of the tray and higher density of food at the top level of the trays. By putting these trays in different locations, they aimed to infer something about ‘apprehension’ – which is vigilance diverted toward predator detection and away from foraging (Dall, Kotler & Bouskila, 2001). Again, moon phase significantly influenced gerbil selectivity to these trays where gerbils preferred to forage on the high-density trays, rather than the low-density trays on moonless nights in Jordan, but not in Israel. Taken together, the authors inferred that differences in fox density influenced gerbil foraging decisions. In areas where foxes were denser (Israel), the gerbils were more sensitive to variation in illumination-related risks than they were in the lower density area (Jordan). I believe that the method of giving-up densities has an important role to play in documenting such indirect effects of predators on prey as a function of anthropogenic habitat modifications. However, I have several concerns about this particular study and its specific inferences. First, while the authors have shown that gerbils behaved differently as a function of moon phase in Jordan than they did in Israel, they have not convincingly demonstrated this difference in risk assessment was caused by foxes. Foxdensity estimates were based solely on tracking, rather than mark–recapture, so all that is really known is that there were more tracks on their transects in Israel than in Jordan (one individual that moved around a lot – which could have conceivably been moving away from humans – would leave more tracks than one individual that did not move that much). Species have multiple predators (Lima, 1992), and current behavior may be influenced by past predators (Blumstein, 2006). While Shapira, Sultand & Shanas claim that owls and snakes are unimportant and rare in this habitat, the current or historical abundance of owls and snakes may also affect prey behavior. While the authors

The effect of fox control on mammal populations in an outer urban conservation reserve.

European red foxes were systematically removed from a 370 ha conservation reserve on Melbourne?s urban fringe between December 2003 and September 2005. Activity indexes monitored throughout the removal phase indicated that the fox population declined dramatically when poison baits were available and then increased again predictably during winter and summer each subsequent year. Three alternate indices of fox activity were highly synchronous throughout the study suggesting that the bait-removal index used widely in Australia may provide a reliable measure of overall fox activity in small urban reserves. With monitoring and strategic baiting, fox activity was maintained at a fraction of its pre-control level. Activity indices for several other species of mammal also appeared to respond to the reduced density of foxes at the site after 2003. Southern brown bandicoots (Isoodon obesulus) and swamp wallabies (Wallabia bicolor) increased in both activity and range after the reduction in the fox population indicating that fox predation may act to limit both the total size of populations and types of vegetation occupied by indigenous mammals in small patches of remnant vegetation.

Effects of Coyote Population Reduction on Swift Fox Demographics in Southeastern Colorado

ABSTRACT The distribution and abundance of swift foxes (Vulpes velox) has declined from historic levels. Causes for the decline include habitat loss and fragmentation, incidental poisoning, changing land use practices, trapping, and predation by other carnivores. Coyotes (Canis latrans) overlap the geographical distribution of swift foxes, compete for similar resources, and are a significant source of mortality amongst many swift fox populations. Current swift fox conservation and management plans to bolster declining or recovering fox populations may include coyote population reduction to decrease predation. However, the role of coyote predation in swift fox population dynamics is not well‐understood. To better understand the interactions of swift foxes and coyotes, we compared swift fox population demographics (survival rates, dispersal rates, reproduction, density) between areas with and without coyote population reduction. On the Piñon Canyon Maneuver Site, Colorado, USA, we monitored 141 swift foxes for 65,226 radio‐days from 15 December 1998 to 14 December 2000 with 18,035 total telemetry locations collected. Juvenile swift fox survival rate was increased and survival was temporarily prolonged in the coyote removal area. Adult fox survival patterns were also altered by coyote removal, but only following late‐summer coyote removals and, again, only temporarily. Coyote predation remained the main cause of juvenile and adult fox mortality in both areas. The increase in juvenile fox survival in the coyote removal area resulted in a compensatory increase in the juvenile dispersal rate and an earlier pulse in dispersal movements. Adult fox dispersal rate was more consistent throughout the year in the coyote removal area. Coyote removal did not influence the reproductive parameters of the swift foxes. Even though juvenile survival increased, swift fox density remained similar between the areas due to the compensatory dispersal rate among juvenile foxes. We concluded that the swift fox population in the area was saturated. Although coyote predation appeared additive in the juvenile cohort, it was compensatory with dispersal.

Evidence for an increasing presence of Echinococcus multilocularis in foxes in The Netherlands

Echinococcus multilocularis, a tapeworm causing alveolar echinococcosis which is considered a serious zoonosis known to affect humans, appears to be expanding its geographical range in Europe. We studied the emergence of the parasite in the European westernmost edge of its geographical distribution, based on two consecutive parasitological examinations of red foxes ( Vulpes vulpes) sampled between 1996 and 2003 in The Netherlands. The average worm count increased from 2.6 worms per fox in the first surveillance to 16.6 worms per fox in the second. Using a mathematical model for a spatially spreading parasite, we found a strong indication that the parasite population is increasing in number and is spreading northward at the speed of 2.7 km per year. The reproduction number ( R 0), reflecting the parasite’s transmission process, is estimated from the surveillance data and it is likely to be more than 1 but not exceeding a value of 4. We analysed a parasite control strategy by estimating the critical fox density for parasite elimination. We conclude that E. multilocularis is an emerging parasite in The Netherlands and thus in the western part of Europe. Control will be very difficult given the current high fox population density.

Acceptance of baits, designed to carry oral rabies vaccines, by foxes in Britain

The spread of classical rabies (RABV) in the red fox (Vulpes vulpes) within Europe has been reversed during the last few decades by the widespread use of vaccine baits. This approach has resulted in most of western Europe being essentially free of terrestrial rabies, and has been associated with significant increases in fox density. The few remaining foci of disease in western Europe are now situated within areas of increasing density of foxes. In Great Britain, rabies contingency planning is centred on the use of vaccine baits, following the successes in Europe. However, in Britain fox density in both rural and urban areas has generally been higher than in continental ‘rabies-endemic’ Europe. One consequence of a high fox density is that a greater proportion of the population needs to consume the vaccine baits and become immunised, to reduce the absolute density of susceptible animals and thus eradicate the disease. Therefore, bait uptake rates in Great Britain, in both rural and high-density urban areas, should be of interest in contingency planning for the control of future outbreaks of rabies in Europe. We report here on studies in Britain on the uptake of vaccine baits by foxes, and how this should influence both British and European rabies contingency planning.

CHANGES IN KIT FOX–COYOTE–PREY RELATIONSHIPS IN THE GREAT BASIN DESERT, UTAH

Variation in kit fox (Vulpes macrotis) population parameters can be influenced by vegetative cover and the distribution and abundance of other predator and prey species. Dramatic changes to Great Basin Desert habitats, which can potentially impact mammalian species, have occurred in some areas in Utah. We examined kit fox demographics and prey populations from 1999 to 2001 on Dugway Proving Ground (DPG), a U.S. Army facility in Utah, and compared some parameters to historical levels (1956–1958–1966–1969). Adult survival rates were fairly consistent between 1999 and 2000 and between 1999 and 2001; however, survival was greater in 2001 than in 2000. Reproductive rates ranged from 1.0 to 3.8 pups per female in 1999–2000 and were similar to historical numbers (1.0–4.2 pups per female). We found a decrease in pre-whelping kit fox density from the 1960s (0.12 foxes · km−2) to 1999–2001 (0.04 foxes · km−2); however, densities were similar between the current study and the 1950s (0.08 foxes · km−2). Using 9 years of data, we found density dependence between reproductive rates of the current year and annual fox density from the previous year. Using 7 years of data, we found a slight correlation between kit fox annual density and a 1-year lag in leporid abundance, even though leporid abundance was lower during the present study than it was historically. Compared to historical levels, current small mammal abundance and species composition has changed in several habitats. Kit fox breeding density and annual density were inversely correlated with coyote (Canis latrans) density. Changes to the landscape at DPG, especially due to invasion of cheatgrass (Bromus tectorum) and addition of artificial water sources, have caused a change in available kit fox habitat and prey species, and have increased the abundance of coyotes, the kit fox's major competitor.

Double Allee Effects and Extinction in the Island Fox

An Allee effect (AE) occurs in populations when individuals suffer a decrease in fitness at low densities. If a fitness component is reduced (component AE), per capita population growth rates may decline as a consequence (demographic AE) and extinction risk is increased. The island fox (Urocyon littoralis) is endemic to six of the eight California Channel Islands. Population crashes have coincided with an increase in predation by Golden Eagles (Aquila chrysaetos). We propose that AEs could render fox populations more sensitive and may be a likely explanation for their sharp decline. We analyzed demographic data collected between 1988 and 2000 to test whether fox density (1) influences survival and reproductive rates; (2) interacts with eagle presence and affects fox fitness parameters; and (3) influences per capita fox population trends. A double component AE simultaneously influenced survival (of adults and pups) and proportion of breeding adult females. The adult survival AE was driven by predation by eagles. These component AEs led to a demographic AE. Multiple-component AEs, a predation-driven AE, and the simultaneous occurrence of both component and demographic AEs in a mammal are all previously unreported processes. Populations below 7 foxes/km(2) could have suboptimal population growth rates due to the demographic AE, and AEs may have contributed to the dramatic declines in three fox populations. Because fox densities in critically endangered populations are well below this level, removing Golden Eagles appears necessary to prevent a predation-driven AE. Conservationists should also be aware of AEs when planning the release of captive foxes. More generally, our findings highlight the danger of overlooking AEs in the conservation of populations of rare or threatened species.

The impact of sarcoptic mangeSarcoptes scabieion the British foxVulpes vulpespopulation

ABSTRACTDisease epizootics can significantly influence host population dynamics and the structure and functioning of ecological communities. Sarcoptic mangeSarcoptes scabieihas dramatically reduced red fox populationsVulpes vulpesin several countries, including Britain, although impacts on demographic processes are poorly understood. We review the literature on the impact of mange on red fox populations, assess its current distribution in Britain through a questionnaire survey and present new data on resultant demographic changes in foxes in Bristol, UK.A mange epizootic in Sweden spread across the entire country in < 10 years resulting in a decline in fox density of up to 95%; density remained lowered for 15–20 years. In Spain, mange has been enzootic for > 75 years and is widely distributed; mange presence was negatively correlated with habitat quality.Localized outbreaks have occurred sporadically in Britain during the last 100 years. The most recent large‐scale outbreak arose in the 1990s, although mange has been present in south London and surrounding environs since the 1940s. The questionnaire survey indicated that mange was broadly distributed across Britain, but areas of perceived high prevalence (> 50% affected) were mainly in central and southern England. Habitat type did not significantly affect the presence/absence of mange or perceived prevalence rates. Subjective assessments suggested that populations take 15–20 years to recover.Mange appeared in Bristol's foxes in 1994. During the epizootic phase (1994–95), mange spread through the city at a rate of 0.6–0.9 km/month, with a rise in infection in domestic dogsCanis familiaris c. 1–2 months later. Juvenile and adult fox mortality increased and the proportion of females that reproduced declined but litter size was unaffected. Population density declined by > 95%.In the enzootic phase (1996–present), mange was the most significant mortality factor. Juvenile mortality was significantly higher than in the pre‐mange period, and the number of juveniles classified as dispersers declined. Mange infection reduced the reproductive potential of males and females: females with advanced mange did not breed; severely infected males failed to undergo spermatogenesis. In 2004, Bristol fox population density was only 15% of that in 1994.

FOOD WEBS AND INTRAGUILD PREDATION: COMMUNITY INTERACTIONS OF A NATIVE MESOCARNIVORE

Trophic level interactions between predators create complex relationships such as intraguild predation. Theoretical research has predicted two possible paths to stability in intraguild systems: intermediate predators either outcompete higher-order predators for shared resources or select habitat based on security. The effects of intraguild predation on intermediate mammalian predators such as swift foxes (Vulpes velox) are not well understood. We examined the relationships between swift foxes and both their predators and prey, as well the effect of vegetation structure on swift fox-coyote (Canis latrans) interactions, between August 2001 and August 2004. In a natural experiment created by the Pinon Canyon Maneuver Site in southeastern Colorado, USA, we documented swift fox survival and density in a variety of landscapes and compared these parameters in relation to prey availability, coyote abundance, and vegetation structure. Swift fox density varied significantly between study sites, while survival did not. Coyote abundance was positively related to the basal prey species and vegetation structure, while swift fox density was negatively related to coyote abundance, basal prey species, and vegetation structure. Our results support the prediction that, under intraguild predation in terrestrial systems, top predator distribution matches resource availability (resource match), while intermediate predator distribution inversely matches predation risk (safety match). While predation by coyotes may be the specific cause of swift fox mortality in this system, the more general mechanism appears to be exposure to predation moderated by shrub density.

Winter severity limits red fox populations in Eurasia

ABSTRACTAim We investigated geographical variation in the density of the red fox in relation to climatic variables, habitat productivity and seasonality to identify those factors that were the best predictors of fox density.Location Published data on red fox abundance were collated from 69 locations over Europe and Asia.Methods Using generalized linear models and the information‐theoretic approach, we analysed the contribution of climatic measures (winter and summer temperature, mean snow depth and duration), primary productivity and seasonality indices [based on the fraction of photosynthetically active radiation (FPAR) index] to account for variation in red fox density.Results Red fox density in winter ranged from 0.001–2.8 individuals km−2; the average density was 0.21 individuals km−2. Variation in red fox density was best explained by the winter temperature and seasonality. Density decreased with declining winter and summer temperatures, increasing degree of seasonality and increasing duration of snow cover. There was no relationship with habitat productivity.Main conclusions Our results indicate that winter climatic conditions and seasonality, but not habitat productivity, may limit red fox density in Eurasia. One explanation for the limitation of the red fox population may be the fox's physiological capability to cope with abiotic conditions. Concurrently, the severity of winter may lead to reduced availability of the fox's prey. That, together with a shorter reproductive period may result in lower reproductive output as well as lower survival of adults and cubs.

Volume contents

1. Disease epizootics can significantly influence host population dynamics and the structure and functioning of ecological communities. Sarcoptic mange Sarcoptes scabiei has dramatically reduced red fox populations Vulpes vulpes in several countries, including Britain, although impacts on demographic processes are poorly understood. We review the literature on the impact of mange on red fox populations, assess its current distribution in Britain through a questionnaire survey and present new data on resultant demographic changes in foxes in Bristol, UK. 2. A mange epizootic in Sweden spread across the entire country in < 10 years resulting in a decline in fox density of up to 95%; density remained lowered for 15–20 years. In Spain, mange has been enzootic for > 75 years and is widely distributed; mange presence was negatively correlated with habitat quality. 3. Localized outbreaks have occurred sporadically in Britain during the last 100 years. The most recent large-scale outbreak arose in the 1990s, although mange has been present in south London and surrounding environs since the 1940s. The questionnaire survey indicated that mange was broadly distributed across Britain, but areas of perceived high prevalence (> 50% affected) were mainly in central and southern England. Habitat type did not significantly affect the presence/absence of mange or perceived prevalence rates. Subjective assessments suggested that populations take 15–20 years to recover. 4. Mange appeared in Bristol’s foxes in 1994. During the epizootic phase (1994–95), mange spread through the city at a rate of 0.6–0.9 km/month, with a rise in infection in domestic dogs Canis familiaris c. 1–2 months later. Juvenile and adult fox mortality increased and the proportion of females that reproduced declined but litter size was unaffected. Population density declined by > 95%. 5. In the enzootic phase (1996–present), mange was the most significant mortality factor. Juvenile mortality was significantly higher than in the pre-mange period, and the number of juveniles classified as dispersers declined. Mange infection reduced the reproductive potential of males and females: females with advanced mange did not breed; severely infected males failed to undergo spermatogenesis. In 2004, Bristol fox population density was only 15% of that in 1994.

The effect of experimental removal of red foxesVulpes vulpes on spring density of brown haresLepus europaeus in western Poland

Red foxesVulpes vulpes (Linnaeus, 1758) were experimentally removed in two nearby areas located in western Poland to verify the hypothesis about the limiting impact of their predation on the low-density population of brown haresLepus europaeus (Pallas, 1778) (4.4-10.6 ind./km2 in late autumn). In 1996/1997–2001/2002 foxes were culled (mainly in autumn and winter) in the reduction area (32 km2), whereas in the control area (34 km2) intensive culling was carried out only in 2000/2001–2001/2002. Indices of fox and hare spring densities were estimated using spotlight counts, as mean numbers of individuals observed per 10 km of the counting route. Annual changes in the fox density indices were negatively correlated with the bag of foxes, and annual changes in the hare density indices were negatively related to the annual changes in fox density indices. The fox density indices were significantly lower in the reduction area than in the control one only in 2000–2001 (2.8 times, on average), and in the same years, the hare population responded with higher density (1.7 times, on average). The hare responses took place without time delay, which suggests that the changes in fox abundance affected the situation of hares primarily in the autumn-winter season.

Implications of increased susceptibility to predation for managing the sylvatic cycle ofEchinococcus multilocularis

The ability to increase the chances that infectious prey are taken by predators is an observed feature of many parasites that rely on one or more predator-prey relationships to complete their life-cycle. In the sylvatic life-cycle of Echinococcus multilocularis - the causative agent of human alveolar echinococcosis-- foxes are the final host, with voles acting as intermediate hosts. Here we review the evidence that E. multilocularis causes increased susceptibility to predation and present a general mathematical model for the sylvatic life-cycle. The ability to increase susceptibility to predation in the intermediate host reduces the sensitivity of the parasite population to adverse conditions. For example, there is no critical density of foxes below which the parasite is expected to die out, even if the effect of the parasite on infected prey is very small. We suggest that increased susceptibility to predation is a plausible explanation for the observed resilience of E. multilocularis during and following field trials of praziquantel baiting.

Variations in the diet and population density of the red fox Vulpes vulpes in the mixed woodlands of northern Belarus

The dietary structure and distribution patterns of red foxes Vulpes vulpes in situations of different food supply in the coniferous–deciduous (mostly small-leaved) woodlands of northern Belarus were investigated. A total of 1526 scats of red foxes was analysed, and snowtracking of the species was performed each winter. Abundance of the main prey (small rodents, perching birds and hares) and wild ungulates supplying carrion for red foxes in the cold season were monitored. The results suggest that in northern Belarus red foxes had a diversified diet, consisting basically of different combinations of bank voles, Microtus voles, and wild ungulate carrion. The importance of carrion much increased in winter, while the proportions of birds and fruits grew during the warm season. In the ecologically rich woodland harbouring on clay soil, red foxes relied more on small rodents, while carrion and fruits appeared to be more important food item of the predator in the barren forested terrain dwelling on poor sandy deposits. During Microtus population outbreaks, red foxes more frequently fed on this prey. One-sixth lower density of red foxes was attributable to the forested terrain on sandy deposits compared to the woodland on clay soil, and a pronounced landscape-related difference in the habitat selection by the predator was found.

Ecology of wildlife rabies in Europe

ABSTRACTThe number of wildlife rabies cases has increased in Europe in recent years. We review the epizootiology of wildlife rabies in Europe, paying special attention to recent changes to the situation of two important vector species: the red fox and the raccoon dog. Red foxVulpes vulpeshas been the main vector of rabies since 1945, but the number and proportion of raccoon dogNyctereutes procyonoidescases has rapidly increased during the past few years, particularly in north‐eastern Europe.The transmission rate (average number of susceptible animals infected by each rabid animal) is critical for rabies spread and is partly determined by population density. Both raccoon dogs and foxes live in pairs. Foxes also live in family groups. Pairs and groups share their territories. Home range size usually correlates negatively with population density. Fox home ranges are 50–1500 ha, those of raccoon dogs 150–700 ha. The threshold value for rabies spread among foxes is estimated to be 0.63 individuals/km2. Although fox density in eastern and northern Europe may be lower than this, the pooled density of foxes and raccoon dogs exceeds the threshold density.Animal movements, especially dispersal of young, pose a risk for rabies spread. Although the likelihood of an epizootic is highest where fox and raccoon dog densities are highest, rabies may spread fastest where population densities are lower, because dispersal distances tend to correlate negatively with population density.Oral vaccinations have been more effective in rabies control than culling foxes. Where two vector species exist, vaccination should be conducted twice a year, because most raccoon dogs disperse in autumn but some foxes do not disperse before mid‐ or late winter.New rabies models, based on two vector species and their interaction, and which take into account the hibernation period of raccoon dogs, are needed for north‐eastern Europe.

Home range, habitat selection and diet of foxes (Vulpes vulpes) in a semi-urban riparian environment

Between 2000 and 2002 the home range, habitat selection and diet of foxes were examined in the Dandenong Creek Valley, Melbourne, Australia. The mean home range was 44.6 ha (range 19.2–152.6 ha). A significant selection towards blackberry and gorse used as diurnal shelter was found during the day with an active avoidance of less structurally complex vegetation types. Although there was obvious selection of certain habitats, the diet of the foxes was highly general and opportunistic and thus offers little potential as a factor to manipulate in order to reduce fox abundance. Given the strong preference for blackberry and gorse as a shelter resource, a habitat-manipulation strategy is suggested whereby patches of blackberry and gorse are removed and replaced with less structurally complex vegetation. Such a strategy has the potential to influence the density of foxes in semi-urban riparian environments such as those discussed in this study.

Does culling reduce fox (Vulpes vulpes) density in commercial forests in Wales, UK?

Forests within agricultural landscapes can act as safe harbourages for species that conflict with neighbouring landowners’ interests, including mammalian predators. The agency responsible for the management of forests in upland Wales, UK, has permitted the killing of foxes (Vulpes vulpes) on their land as a “good neighbour policy” with the aim of reducing fox numbers. The principal method used was the use of dogs to drive foxes to a line of waiting shooters; a small number of foxes were also killed by shooting at night with a rifle. However, it has been postulated that recent restrictions on the use of dogs to kill foxes in Britain could lead to an increase in fox numbers in plantations. The aim of this study was to determine whether over-winter culling (i.e. driving foxes to guns using dogs and rifle shooting) in these forests acted to reduce fox density. Fox faecal density counts were conducted in commercial forests in Wales in autumn 2003 and spring 2004. Data were analysed from 29 sites (21 individual forests and 8 forest blocks, the latter consisting of pooled data from 20 individual forests). The over-winter change in faecal density was negatively related to the proportion of felled land and the proportion of land more than 400 m altitude, these associations probably reflecting reduced food availability. Over-winter change was positively associated with culling pressure (i.e. more foxes were killed where more foxes were present, or vice versa), but this was not significant. The number of foxes killed was large relative to the estimated resident population, but losses appeared to be negated (most likely) by immigration. Pre-breeding (spring) faecal density counts were significantly positively related to culling pressure, i.e. more foxes were killed with increased fox density or vice versa. Overall, there was no evidence to suggest that culling reduced fox numbers. Consequently, restrictions on the use of dogs to control foxes are unlikely to result in an increase in fox numbers in commercial forests.