Natal den selection by sympatric arctic and red foxes on Herschel Island,Yukon, Canada

In the twentieth century, red fox (Vulpes vulpes) expanded into the Canadian Arctic, where it competes with arctic fox (Vulpes lagopus) for food and shelter. Red fox dominates in physical interactions with the smaller arctic fox, but little is known about competition between them on the tundra. On Hershel Island, north Yukon, where these foxes are sympatric, we focused on natal den choice, a critical aspect of habitat selection. We tested the hypothesis that red fox displaces arctic fox from dens in prey-rich habitats. We applied an approach based on model comparisons to analyse a 10-year data set and identify factors important to den selection. Red fox selected dens in habitats that were more prey-rich in spring. When red foxes reproduced, arctic fox selected dens with good springtime access, notably many burrows unblocked by ice and snow. These provided the best refuge early in the reproductive season. In the absence of red foxes, arctic foxes selected dens offering good shelter (i.e. large isolated dens). Proximity to prey-rich habitats was consistently less important than the physical aspects of dens for arctic fox. Our study shows for the first time that red foxes in the tundra select dens associated primarily with prey-rich areas, while sympatric arctic foxes do not. These results fit a model of red fox competitively interfering with arctic fox, the first detailed study of such competition in a true arctic setting.     

Annual dynamics of den use by red foxesVulpes vulpes and badgersMeles meles in central Poland

This study on den use by red foxesVulpes vulpes (Linnaeus, 1758) and badgersMeles meles (Linnaeus, 1758) was conducted in central Poland (51°48’N, 19°53’E) over two years. We found a strong negative correlation between monthly den utilisation rate by foxes and air temperature (r=−0.83,p=0.0001). Correlation between temperature and den use by badgers was positive but less distinct (r=0.40,p=0.036). During the whole study period, a negative correlation between the monthly intensity of den use by badgers and by foxes was found (r=−0.51,p=0.008). The seasonal pattern of den utilisation differed between the species. Foxes used the dens mainly in winter and spring whereas in summer and autumn the intensity of den utilisation sharply decreased to a minimum in August-September. A peak in den use by foxes was observed in March and coincided with rut and selection of future breeding dens. In badgers, two peaks in den use were observed: the first in April and the second in August-September. An individual badger used more dens and used them more evenly throughout the year than an individual fox. The same dens were visited by foxes and badgers mostly from January to April, with a maximum in March.     

Habitat related differences in age structure and reproductive parameters of red foxes

We studied the age-structure and the reproductive parameters in two samples of red foxesVulpes vulpes (Linnaeus, 1758) from two contiguous areas in the Ebro valley (NE Spain) differing in the level of deliberate culling and in the habitat quality. Percent of juvenile foxes in the semiarid steppe (under higher persecution) was lower (53%) than in the irrigated highly productive “vegas” (67%). Conversely, foxes in the “vegas” (more favourable habitat) had a larger litter size (3.9 ± 0.23 cubs per female) and a higher amount of barren vixens (19.3%) than in the steppe (3.3 ± 0.12 cubs per female, and 1.7% of barren vixens). In this study, migration due to juvenile dispersal does not hide the effects of the habitat on fox population dynamics, despite the proximity between both areas. The results are discussed in relation to previous studies on red fox population dynamics.     

Den attendance patterns in swift foxes during pup rearing: varying degrees of parental investment within the breeding pair

Parental investment varies in mammalian species, with male care of young being more common in social and monogamous species. Monogamy is commonly observed in canid species, with both males and females, and often “helper” individuals, providing some degree of care for the young. Social units of the swift fox (Vulpes velox), a small North American canid species, usually consist of a male–female pair and occasionally helpers. The role of parental investment and behavior in swift fox society is currently poorly understood. We observed swift fox dens during the pup-rearing season in each of 2 years to evaluate attendance and frequency of visits to natal dens by adult males and females. Female foxes remained at dens longer and visited them more frequently than did male foxes. Female attendance and visitation decreased throughout the pup-rearing season as pups became older and more independent. Environmental factors, including climate and its effect on prey, appeared to contribute to differences in fox behavior between the 2 years. We observed only one fox outside of the breeding pair attending a den in each of the 2 years, both of which were males. We concluded that each of these two foxes were living within the social unit of the male–female pair as a trio, but not serving as a helper and contributing to the care of the pups. Our results increased knowledge of the ecology and behavior of the swift fox, a species of conservation concern in the Great Plains of North America.     

呼伦贝尔草原沙狐洞穴的结构

沙狐（Vulpes corsac）又名东沙狐,属食肉目犬科,主要分布在亚洲中部的草原、荒漠和半荒漠地带,在我国主要分布在内蒙古、甘肃、宁夏和新疆部分地区。由于沙狐主要以鼠类为食,因此沙狐在调节鼠类数量和控制鼠害方面起着重要的作用（马逸清等,1986）。《中国物种红色名录》（汪松和解焱,2004）将沙狐列为“易危”,指出其“数据缺乏”。     

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.     

Pulses of movement across the sea ice: population connectivity and temporal genetic structure in the arctic fox

Lemmings are involved in several important functions in the Arctic ecosystem. The Arctic fox (Vulpes lagopus) can be divided into two discrete ecotypes: “lemming foxes” and “coastal foxes”. Crashes in lemming abundance can result in pulses of “lemming fox” movement across the Arctic sea ice and immigration into coastal habitats in search for food. These pulses can influence the genetic structure of the receiving population. We have tested the impact of immigration on the genetic structure of the “coastal fox” population in Svalbard by recording microsatellite variation in seven loci for 162 Arctic foxes sampled during the summer and winter over a 5-year period. Genetic heterogeneity and temporal genetic shifts, as inferred by STRUCTURE simulations and deviations from Hardy–Weinberg proportions, respectively, were recorded. Maximum likelihood estimates of movement as well as STRUCTURE simulations suggested that both immigration and genetic mixture are higher in Svalbard than in the neighbouring “lemming fox” populations. The STRUCTURE simulations and AMOVA revealed there are differences in genetic composition of the population between summer and winter seasons, indicating that immigrants are not present in the reproductive portion of the Svalbard population. Based on these results, we conclude that Arctic fox population structure varies with time and is influenced by immigration from neighbouring populations. The lemming cycle is likely an important factor shaping Arctic fox movement across sea ice and the subsequent population genetic structure, but is also likely to influence local adaptation to the coastal habitat and the prevalence of diseases.     

Selection of land cover by the Tibetan foxVulpes ferrilata on the eastern Tibetan Plateau, western Sichuan Province, China

Habitat loss is one of the main factors impacting endangered wildlife in China. The Tibetan foxVulpes ferrilata Hodgson, 1842 is a characteristic species of the Tibetan Plateau. However, its habitat use is poorly known. We conducted a project (2001–2003) to better understand habitat use by the Tibetan fox in Shiqu County, Sichuan Province, China. The research site was classified into four land cover categories: grassland, grassland and shrubs, shrubs, and disturbed area (more than half of the area in a plot covered by bare soil and gravel). Their proportional share in land cover categories was estimated by line transects and used as expected land cover. Plots were also located at fox locations, fox dens, and fox feces (hereafter “fox plots”). Using Bonferroniz-statistics, land cover proportions in fox plots were compared with the expected land cover proportions. Tibetan foxes were found primarily in grassland habitat and there was evidence of use of grassland/shrub habitat and disturbed area. However, the fox were rarely observed in shrubs. Two reasons for this are: (1) the need of prey, pika, which mainly lives in open areas; (2) the requirement of security from natural enemies.     

内蒙古东部草原沙狐春季洞穴选择

通过对内蒙古东部草原64个沙狐洞穴的观测,采用主成分分析法,对沙狐洞穴选择作了初步的定量研究。分析结果表明：影响沙狐春季洞穴选择的主要生态因子有7种,依次为：坡位因子（随坡度,坡高的变化而变化）,水源因子,植被因子,微气候因子,食物因子,人为干扰因子和微生境因子,而坡向,洞口朝向及洞道口倾角等影响不明显。     

Red fox takeover of arctic fox breeding den: an observation from Yamal Peninsula, Russia

Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia.     

Finding the right home: distribution of food resources and terrain characteristics influence selection of denning sites and reproductive dens in arctic foxes

We examined 83 arctic fox (Alopex lagopus) dens on Bylot Island (Canada) during the summers of 2003–2005, to determine how arctic foxes select a denning site among potential sites, and a breeding den among existing dens. We compared denning sites to random locations in a 425 km² study area (landscape scale) and to other potential denning sites in a 100 m radius (local scale). Dens were located on mounds or in slopes and were closer to streams than expected. Sites with low snow cover in spring, high ground temperature, high depth to permafrost, and steep and southerly exposed slopes were preferred. Of the 83 dens, 27 were used at least once for reproduction from 2003 to 2005. We show with a resource selection function analysis that an attractive force (distribution of food resources) and an apparently repulsive one (presence of other dens in the vicinity) affected selection of dens for reproduction. We generate testable hypotheses regarding the influence of food and social factors on the denning ecology of arctic foxes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Longitudinal changes of dominance rank among the females of the Koshima group of Japanese monkeys

The changes of dominance rank among female Japanese monkeys of the Koshima group over a period of 29 years from 1957 were studied. The dominance rank order was relatively stable in the early population growing phase, while large scale-changes of dominance rank order occurred successively in the phase of population decrease brought about by the severe control of artificial feeding after 1972. Nevertheless, the rank order of several females of the highest status was stable. Furthermore, the reproductive success of these highest status females was high (Mori, 1979a;Watanabe et al., in prep.). Divergence of the dominance rank order fromKawamura's rules (Kawamura, 1958) was observed in the following respects: (1) Some females significantly elevated their rank depending on the leader males. (2) If mothers died when their daughters were still juveniles or nulliparous, the dominance rank of some of these offspring females was significantly lower than the mother's one. However 55% of daughters which lost their mothers at a young age inherited the mother's rank. (3) Dominance among sisters whose mother had died when at least one of the daughters was under 6 years old followed the rule of youngest ascendancy in 60% (Kawamura, 1958), and in 80% when both of the daughters were nulliparous at the mother's death. The mean rate of aggressive interactions for each female with subordinates to her was calculated by dividing the total aggressive interactions between the female in question and her subordinates by the number of subordinate females to the female in question. A female which showed a high rate of aggressive interactions with her subordinates was categorized as an “Attacker”, and a female showing a lower rate was categorized as a “Non-attacker”. Similarly, categories of “Attacked”, and “Non-attacked” were distinguished by using the rate of aggressive interactions with dominant females. Several females which were once categorized in one category in a year were repeatedly categorized in the same category over different years. The “Attacked” tended to be females of higher rank, and “Non-attackers” tended to be females of lower rank. “The second-higher-status females”, were “Attacked”, and their rank was unstable. In particular, females of lower rank within the lineage of the highest rank suffered this kind of severe status. Most of the daughters of these females showed a sharp drop of rank, and died when they were still at a young age, i.e. “the second-higher-status females” displayed low fitness. “Non-attackers” were significantly “Non-attacked”; i.e. they were females which showed a non-social attitude. Females which underwent a drop of rank tended to be “Non-attackers”. The most important factor which determined the females' rank was the memory of their dominance relations under the influence of their mother [dependent rank (Kawai, 1958)] in their early life during development. This finding corresponds well with the results in baboons obtained byWalter (1980); the target females of aggressive interactions by adolescent females were determined by the rank of the mothers when these adolescent females were born.     

Importance of Native Grassland Habitat for Den-Site Selection of Indian Foxes in a Fragmented Landscape

Fragmentation of native habitats is now a ubiquitous phenomenon affecting wildlife at various scales. We examined selection of den-sites (n = 26) by Indian foxes (Vulpes bengalensis) in a highly modified short-grassland landscape in central India (Jan-May, 2010). At the scale of the home-range, defined by an 800 m circular buffer around den sites, we examined the effect of land-cover edges and roads on selection of sites for denning using a distance-based approach. At the smaller den-area scale, defined by a 25 m x 25 m plot around den and paired available sites, the effect of microhabitat characteristics was examined using discrete-choice models. Indian foxes selected den-sites closer to native grasslands (t = -9.57, P < 0.001) and roads (t = -2.04, P = 0.05) than random at the home-range scale. At the smaller scale, abundance of rodents and higher visibility increased the odds of selection of a site by eight and four times respectively, indicating resource availability and predator avoidance to be important considerations for foxes. Indian foxes largely chose to den in human-made structures, indicated by the proportion of dens found in earthen bunds (0.69) and boulder piles (0.27) in the study area. With agricultural expansion and human modification threatening native short-grassland habitats, their conservation and effective management in human-dominated landscapes will benefit the Indian fox. The presence of some human-made structures within native grasslands would also be beneficial for this den-dependent species. We suggest future studies examine the impact of fragmentation and connectivity of grasslands on survival and reproductive success of the Indian fox.     

Exclusion by interference competition? The relationship between red and arctic foxes

The distribution of many predators may be limited by interactions with larger predator species. The arctic fox in mainland Europe is endangered, while the red fox is increasing its range in the north. It has been suggested that the southern distribution limit of the arctic fox is determined by interspecific competition with the red fox. This has been criticised, on the basis that the species co-exist on a regional scale. However, if the larger red fox is superior and interspecific competition important, the arctic fox should avoid close contact, especially during the breeding season. Consequently, the distribution of breeding dens for the two species would be segregated on a much smaller spatial and temporal scale, in areas where they are sympatric. We tested this hypothesis by analysing den use of reproducing arctic and red foxes over 9 years in Sweden. High quality dens were inhabited by reproducing arctic foxes more often when no red foxes bred in the vicinity. Furthermore, in two out of three cases when arctic foxes did reproduce near red foxes, juveniles were killed by red foxes. We also found that breeding arctic foxes occupied dens at higher altitudes than red foxes did. In a large-scale field experiment, red foxes were removed, but the results were not conclusive. However, we conclude that on the scale of individual territories, arctic foxes avoid areas with red foxes. Through interspecific interference competition, the red fox might thus be excluding the arctic fox from breeding in low altitude habitat, which is most important in years when food abundance is limited and competition is most fierce. With high altitude refuges being less suitable, even small-scale behavioural effects could scale up to significant effects at the population level.     

Terrain structure and selection of denning areas by arctic foxes on Svalbard

We examined the relationship between the distribution of arctic fox dens and the occurrence of rugged terrain on Svalbard, Norway, using indices of terrain ruggedness (TRI) based on contour characteristics from topographic maps in 240 grid cells, each 4 km². The distribution of rugged terrain co-varied with occurrence of arctic fox dens. Moderately rugged terrain (TRI=1.5–3.0) constituted only 21% of the total study area, but contained 77% of all natal dens recorded in the study area. Large clusters (8–36 km²) of moderately rugged terrain were generally preferred for location of den sites compared to smaller scattered clusters of rugged terrain. The importance of rugged terrain is discussed in relation to snow cover, exposure, soil conditions and distribution of prey species. This simple and non-invasive analysis of terrain ruggedness may be used to predict the distribution of potential arctic fox denning areas across landscapes. Accepted: 6 September 2000     

Spatial patterns of red fox (Vulpes vulpes) dens in a semi-arid landscape of North Africa

Different patterns of the use of space by red foxes ( Vulpes vulpes ) depend mainly on the distribution and availability of food patches. Nevertheless, other key resources such as suitable areas for dens can also influence the territory size and social organization of this predator. In fact, landscape modifications such as habitat patchiness made by human activities (agricultural practices, urbanization) should create ample unfavourable zones for den settlement. Several studies focused on the distribution and use of dens by the red fox in different habitat types but we do not have any data on the den settlement and habitat composition in the semi-arid regions of North Africa. This study was carried out at Djerba island (SE Tunisia), virtually deprived of surface water and with a semi-arid climate because of the bordering Sahara desert. We used line and random transects to find fox dens. The spatial pattern of dens varied mainly in different habitat types and geoclimatic regions. Highly fragmented areas were also occupied by foxes that built dens close together inside small suitable patches. Fox dens had fewer entrances in more arid regions and they mainly faced the south. Habitat selection was influenced by water availability and irrigated tree plantations that modify soil textures allowing digging of dens. Moreover, asphalt roads limit den settlements. We suggest that the choice of denning sites by foxes depends on persisting harsh conditions and human activities.     

Structure of arctic fox (Alopex lagopus beringensis) colonies in the northern extremity of Bering Island

Data on the spatial structure of an Arctic fox (Alopex lagopus beringensis) colony were obtained in July-August 1995, using walk counts and observations near living dens around the Northern rookery of the northern fur seals located on Bering Island (Commander Islands). The home ranges of 31 Arctic fox families (61 adults and 145 pups inhabiting 66 dens) were found over 27 km of the coastline. Sixty individuals (3 adults and 57 pups) were marked by color ear-tags. Among adult foxes, 24 (39.3%) were recognized as females and 12 (19.7%) as males; the sex of 25 (41.0%) foxes was not recognized. Among 57 marked cubs, 26 (45.6%) were females and 31 (54.4%) were males. The best studied families (13) had 3–11 pups (6.7 ± 0.7, on average). The survival of cubs at an age younger than 2.0–2.5 months was 82.5%; 30.8% of the families consisted of more than two adults. The distribution of the Arctic fox dens and home ranges along the coastline has been studied; specific features of the location of dens have been described. In the studied area, Arctic foxes have been foraging on birds (67.6% of dens with food remains), northern fur seals (40.5), other marine mammals (13.5), Pacific salmon (29.7), and reindeer (2.7%), as well as on amphipods and voles. Rich constant food sources (rookeries, marine bird colonies, and spawning places of the blueback salmon) were found in 7 home ranges of the Arctic fox; 6 home ranges included temporary food sources (spawning streams of the humpback salmon); and 18 home ranges were poor in food resources. Arctic foxes whose home ranges lie within 6–7 km around a “food patch” used the concentrated food resources together. Food resources are supposed to become important only after the raised pups turn to self-feeding. Differences in the use of space, foraging and breeding of the two Arctic fox subspecies (A. l. beringensis and A. l. semenovi), and arrangement of colonies around the northern fur seal rookeries are discussed.     

Spatial contraction in a large gull colony in relation to the position of arctic fox dens

Many species of colonial ground-nesting birds are known to be sensitive to predation by terrestrial predators. The response of prey under the pressure of predation can either be direct (depletion of prey) or indirect due to prey avoiding the predator. We studied the recolonization of arctic foxes into a large and growing breeding colony of lesser black-backed gulls. The gull colony reached the size of 20,000 pairs during the period of no foxes. The number of breeding gulls continued to increase after the colonization of foxes and reached a maximum of 40,000 pairs about 15 years later. During the same time period, the spatial coverage of the gull colony shrunk from 31.4 down to 18.6 km², and the change in distribution was closely linked with position of fox dens, which ranged in number from one to three annually. In 2005, the number of breeding gulls decreased slightly with an ongoing shrinkage in spatial coverage. Food analyses from fox scats and stomachs showed that birds of the order Charadriiformes, particularly gulls, were the key prey item. Survival rates of gull nests were higher in the middle of the colony than at the colony edge close to a fox den. The colony area lost could be explained solely by the number of eggs removed by foxes but is unlikely, e.g., due to reclutching. We suggest that intraspecific predation contributes additionally to the effects of direct fox predation although to an unknown degree.     

Social relations between adult males and females of Japanese monkeys in the arashiyama B troop

Some dyads of Japanese monkey adult males and females show remarkable spatial proximity and frequent exchanges of social behaviors. It is suggested that some kind of “affinity” exists between them. Females obtain much unilateral benefit from “proximity effects”; even lowranking females can dominate high-ranking females as long as they stay nearby their “affinitive” males. Males acquire female followers in return. Mating relations and female mother-daughter relations play important roles in forming new “affinitive relations.” Once monkeys have formed “affinitive relations,” however, they seldom mate with each other, as if they were kin-related. Therefore, the acquisition of female followers appears inconsistent with a male's strategy for reproducing many genes in the next generation. This study was financed partly by the Cooperative Research Fund of the Primate Research Institute, Kyoto University. The outline of this paper has already been published inTakahata (1980b).     

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.