Swift Fox Populations Research Articles

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.

Life on the edge: habitat fragmentation limits expansion of a restored carnivore

AbstractThe successful recovery of imperiled species is dependent on knowledge of how demographic drivers mediate population growth and expansion. One of the largest species restoration projects has been the reintroduction of swift foxes Vulpes velox to southern Canada, where 947 foxes were released between 1983 and 1997. Swift foxes have since increased and expanded their range into northern Montana (USA), but have experienced a population decline and stall in recolonization over the past 10 years. The objective of this study was to estimate the survival and reproductive rates of swift foxes in northern Montana, which constitutes the southern edge of this population. In addition, we evaluated support for two different hypotheses of how environmental factors and several demographic factors influence survival. Although our length of monitoring was relatively short, we found that adult and juvenile annual survival rates were 54% and 74%, respectively, and fecundity was 0.85. We found the most support for the hypothesis that the percentage of native grassland at the 1‐km scale influenced survival and found that survival increased, on average, 2.1% for every 5% increase in grassland. Compared to previous estimates of swift fox population growth immediately following the release, our data suggest the population is currently stable. The long‐term successful recolonization and connectivity of swift fox populations in this region will likely be dependent on maintaining large tracts of contiguous grassland. Comparing the estimates of demographic rates among different points in space and time should help managers better understand the population dynamics and inform restoration strategies for recovering populations.

Home range size and resource use by swift foxes in northeastern Montana.

Swift foxes (Vulpes velox) are endemic to the Great Plains of North America, but were extirpated from the northern portion of their range by the mid-1900s. Despite several reintroductions to the Northern Great Plains, there remains a ~350 km range gap between the swift fox population along the Montana and Canada border and that in northeastern Wyoming and northwestern South Dakota. A better understanding of what resources swift foxes use along the Montana and Canada border region will assist managers to facilitate connectivity among populations. From 2016 to 2018, we estimated the home range size and evaluated resource use within the home ranges of 22 swift foxes equipped with Global Positioning System tracking collars in northeastern Montana. Swift fox home ranges in our study were some of the largest ever recorded, averaging (± SE) 42.0 km2 ± 4.7. Our results indicate that both environmental and anthropogenic factors influenced resource use. At the population level, resource use increased by 3.3% for every 5.0% increase in percent grasslands. Relative probability of use decreased by 7.9% and 7.4% for every kilometer away from unpaved roads and gas well sites, respectively, and decreased by 3.0% and 11.3% for every one-unit increase in topographic roughness and every 0.05 increase in normalized difference vegetation index (NDVI), respectively. Our study suggests that, to reestablish connectivity among swift fox populations in Montana, managers should aim to maintain large corridors of contiguous grasslands at a landscape scale, a process that likely will require having to work with multiple property owners.

Genetics of a reintroduced swift fox population highlights the need for integrated conservation between neighbouring countries

AbstractThe genetic consequences of reintroductions are rarely considered after releases cease, but long‐term viability depends on linked demography and genetic health. Reintroductions of swift foxes Vulpes velox began after 45 years of extirpation from Canada; these have resulted in national down‐listing to ‘threatened’ status, and the re‐establishment of a small contiguous population in Montana, US. Demographic growth has been associated with stable levels of genetic diversity and growing effective population size, but evidence of two genetic clusters, and a recent decline in abundance could be cause for conservation concern depending on underlying mechanisms. We analysed individuals from two time points at 18 microsatellite loci to investigate whether the genetic structure is a consequence of having used two separate release sites and non‐equilibrium population dynamics, but our results suggest that the population is likely at mutation‐ and migration‐drift equilibrium. We examined habitat effects on relative gene flow and found limited evidence for cropland to be a dispersal barrier, but effects of terrain roughness suggest that more rugged landscapes may reduce dispersal capacity. Using parentage analysis we determined maximum dispersal distances of up to 50 km for females and 100 km for males including movements in either direction across the international border, but no mixing of genetic clusters was seen in either country. Greater genetic connectivity among than within respective countries necessitates careful co‐management between Canada, where the species has the highest levels of legislative protection, and contiguous areas of the United States where limited trapping for fur is now permitted. We encourage similar analyses of conservation populations across international borders to determine how optimal genetic management can best mesh with different policies and conservation approaches among countries.

Use of least-cost path analysis to identify potential movement corridors of swift foxes in Montana

The swift fox ( Vulpes velox ) is a small grassland canid native to the North American Great Plains. A reintroduced swift fox population in Canada and northern Montana appears to be isolated from those existing in the central and southern Great Plains. We developed a swift fox habitat suitability model for southeastern Montana, the region between the 2 populations. The resulting model indicated that 67.9% of the study area consisted of highly suitable habitat. We conducted a least-cost path analysis to evaluate the connectivity of swift fox habitat in the study area to existing swift fox populations in the region. We identified a potential dispersal corridor through southeastern Montana that could facilitate movement between swift fox populations in northern Montana and northern Wyoming and identified 4 prairie dog complexes in Rosebud, Custer, and Powder River Counties, Montana, that could serve as potential swift fox reintroduction sites. Each site comprised several prairie dog colonies in close proximity and encompassed ≥ 95 km2. We evaluated the effect that swift fox populations established in each potential reintroduction site could have on population connectivity. Our results as well as future surveys could inform swift fox management and reintroduction programs in Montana.

Age-specific survival of reintroduced swift fox in Badlands National Park and surrounding lands

In 2003, a reintroduction program was initiated at Badlands National Park (BNP), South Dakota, USA, with swift foxes (Vulpes velox) translocated from Colorado and Wyoming, USA, as part of a restoration effort to recover declining swift fox populations throughout its historical range. Estimates of age-specific survival are necessary to evaluate the potential for population growth of reintroduced populations. We used 7 years (2003–2009) of capture–recapture data of 243 pups, 29 yearlings, and 69 adult swift foxes at BNP and the surrounding area to construct Cormack–Jolly–Seber model estimates of apparent survival within a capture–mark–recapture framework using Program MARK. The best model for estimating recapture probabilities included no differences among age classes, greater recapture probabilities during early years of the monitoring effort than later years, and variation among spring, winter, and summer. Our top ranked survival model indicated pup survival differed from that of yearlings and adults and varied by month and year. The apparent annual survival probability of pups (0.47, SE = 0.10) in our study area was greater than the apparent annual survival probability of yearlings and adults (0.27, SE = 0.08). Our results indicate low survival probabilities for a reintroduced population of swift foxes in the BNP and surrounding areas. Management of reintroduced populations and future reintroductions of swift foxes should consider the effects of relative low annual survival on population demography. © 2016 The Wildlife Society.

Little fox on the prairie: genetic structure and diversity throughout the distribution of a grassland carnivore in the United States

The Great Plains region is fragmented by natural and anthropogenic sources, yet the interaction between habitat fragmentation and genetic structure in this region has received limited study. Swift fox (Vulpes velox) are closely associated with short and mixed grass ecosystems, providing an opportunity to study patterns of gene flow, diversity and genetic structure in this area. We collected 589 samples throughout the species’ distribution in the United States and analyzed these samples using 15 microsatellite loci and a 250 base pair sequence of the mitochondrial DNA control region. We detected three levels of spatial genetic structure using microsatellite markers and identified six mitochondrial haplotypes, five of which showed spatial clustering. Differentiation between groups was significant while genetic diversity within groups was generally high. Anthropogenic influences, particularly agriculture, appear to reducing gene flow, especially in the central portion of the species’ range. Conservation measures should be taken to remediate these impacts and to maintain future gene flow in light of expected agricultural expansion in the Great Plains. Potential evolutionary significant units are identified, although further investigation using ecological indicators and adaptive loci is recommended to characterize the adaptive distinctiveness of swift fox populations.

Does habitat heterogeneity in a multi-use landscape influence survival rates and density of a native mesocarnivore?

The relationships between predators, prey, and habitat have long been of interest to applied and basic ecologists. As a native Great Plains mesocarnivore of North America, swift foxes (Vulpes velox) depended on the historic disturbance regime to maintain open grassland habitat. With a decline in native grasslands and subsequent impacts to prairie specialists, notably the swift fox, understanding the influence of habitat on native predators is paramount to future management efforts. From 2001 to 2004, we investigated the influence of vegetation structure on swift fox population ecology (survival and density) on and around the Piñon Canyon Maneuver Site, southeastern Colorado, USA. We monitored 109 foxes on 6 study sites exposed to 3 different disturbance regimes (military training, grazing, unused). On each site we evaluated vegetation structure based on shrub density, basal coverage, vegetation height, and litter. Across all sites, annual fox survival rates ranged from 0.50 to 0.92 for adults and 0.27 to 0.78 for juveniles. Among sites, population estimates ranged from 1 to 7 foxes per 10 km transect. Fox density or survival was not related to the relative abundance of prey. A robust model estimating fox population size and incorporating both shrub density and percent basal cover as explanatory variables far outperformed all other models. Our results supported the idea that, in our region, swift foxes were shortgrass prairie specialists and also indicated a relationship between habitat quality and landscape heterogeneity. We suggest the regulation of swift fox populations may be based on habitat quality through landscape-mediated survival, and managers may effectively use disturbance regimes to create or maintain habitat for this native mesocarnivore.

Genetic diversity in a reintroduced swift fox population

Swift fox (Vulpes velox) were historically dis- tributed in southwestern South Dakota including the region surrounding Badlands National Park (BNP). The species declined during the mid-1800s, largely due to habitat loss and poisoning targeted at wolves (Canis lupus) and coyotes (Canis latrans). Only a small population of swift foxes near Ardmore, which is located in Fall River County, South Dakota, persisted. In 2003, a reintroduction program was initiated at BNP with swift foxes translocated from Colo- rado and Wyoming. Foxes released in the years 2003, 2004 and 2005 were translocated from Colorado (BNP-Colo- rado) whereas in 2006, released foxes were translocated from Wyoming (BNP-Wyoming). Our objective was to evaluate genetic diversity and structure of the restored swift fox population in the area surrounding BNP com- pared to source fox populations in an area of Colorado and Wyoming, as well as the local swift fox population neighboring BNP near Ardmore in Fall River County, South Dakota. A total of 400 swift foxes (28 released in 2003, 28 released in 2004, 26 released in 2005, 26 released in 2006, 252 wild-born foxes, 40 individual foxes from the Ardmore area of South Dakota) was genotyped using twelve microsatellite loci. We report mean gene diversity values of 0.778 (SD = 0.156) for the BNP-Colorado pop- ulation, 0.753 (SD = 0.165) for the BNP-Wyoming pop- ulation, 0.751 (SD = 0.171) for the BNP population, and 0.730 (SD = 0.166) for the Fall River population. We also obtained Fst values ranging from 0.014 to 0.029 for pair- wise comparisons of fox populations (BNP, Fall River, BNP-Wyoming, BNP-Colorado). We conclude that the reintroduced fox population around BNP has high genetic diversity comparable to its source populations in Colorado and Wyoming. Although genetic diversity indicates that the reintroduction was successful, additional time is necessary to fully evaluate long-term genetic maintenance and in- terconnectivity among these populations.

Historical Range, Current Distribution, and Conservation Status of the Swift Fox, <em>Vulpes velox</em>, in North America

The Swift Fox (Vulpes velox) was once common in the shortgrass and mixed-grass prairies of the Great Plains of North America. The species' abundance declined and its distribution retracted following European settlement of the plains. By the late 1800s, the species had been largely extirpated from the northern portion of its historical range, and its populations were acutely depleted elsewhere. Swift Fox populations have naturally recovered somewhat since the 1950s, but overall abundance and distribution remain below historical levels. In a 1995 assessment of the species' status under the US Endangered Species Act, the US Fish and Wildlife Service concluded that a designation of threatened or endangered was warranted, but the species was "precluded from listing by higher listing priorities." A major revelation of the 1995 assessment was the recognition that information useful for determining population status was limited. Fundamental information was missing, including an accurate estimate of the species' distribution before European settlement and an estimate of the species' current distribution and trends. The objectives of this paper are to fill those gaps in knowledge. Historical records were compiled and, in combination with knowledge of the habitat requirements of the species, the historical range of the Swift Fox is estimated to be approximately 1.5 million km2. Using data collected between 2001 and 2006, the species' current distribution is estimated to be about 44% of its historical range in the United States and 3% in Canada. Under current land use, approximately 39% of the species' historical range contains grassland habitats with very good potential for Swift Fox occupation and another 10% supports grasslands with characteristics that are less preferred (e.g., a sparse shrub component or taller stature) but still suitable. Additionally, land use on at least 25% of the historical range supports dryland farming, which can be suitable for Swift Fox occupation. In the United States, approximately 52% of highest quality habitats currently available are occupied by Swift Foxes.

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.

Swift fox reintroductions on the Blackfeet Indian Reservation, Montana, USA

Swift foxes ( Vulpes velox) were once common prairie inhabitants throughout western North America and were integral components within ecosystems and some Native American tribal cultures. In response to extirpation from tribal lands, the Blackfeet Tribe and Defenders of Wildlife reintroduced 123 captive-raised swift foxes from 1998 to 2002 to the Blackfeet Indian Reservation, Montana, USA. We used two success criteria, a population growth rate ⩾1.0 and an index count ⩾100 foxes, to determine if the reintroduction was a short-term success. We radiocollared and monitored swift foxes from 2003 to 2005 to estimate survival and fecundity. The swift fox population grew at a rate of 16% during 2003/2004 and 14% in 2004/2005. In addition, field crews observed 93 foxes in the summer of 2005. The swift fox population reached one, and very nearly both, of our short-term success criteria. In light of swift fox sign in areas where we were unable to observe foxes despite being aware of their presence, we believe there were ⩾100 foxes present in 2005. Based on our success criteria and the discovery of swift foxes 110 km from the release site, we consider this reintroduction a short-term success with promise for long-term success. The Blackfeet Tribe and Defenders of Wildlife have attained their goal of restoring a culturally important species to Tribal lands and have initiated a comeback of swift foxes beyond the Reservation border to the Rocky Mountain Front in Montana. Collaborative projects between tribes and non-governmental groups can play a vital role in our effort to conserve biologically and culturally significant species.

Isolation and characterization of swift fox tetranucleotide microsatellite loci

AbstractPrimers have been developed for nine polymorphic tetranucleotide microsatellite loci isolated from the swift fox (Vulpes velox). These can be amplified in three multiplex reactions and all loci can be scored easily and without ambiguity. The number of alleles per locus ranged from three to 14 and the overall heterozygosities ranged from 0.54 to 1.00. All loci were in Hardy‐Weinberg equilibrium, but two loci were in linkage disequilibrium. These loci will be used to monitor endangered swift fox populations on the Canadian prairies.

Effects of Artificial Escape Dens on Swift Fox Populations in Northwest Texas

Throughout the range of swift fox (Vulpes velox), coyotes (Canis latrans) are the primary source of swift fox mortality. Coyotes may suppress swift fox populations where densities are high. Because coyote numbers have increased since wolves (Canis lupus) have been exterminated, we hypothesized that escape habitats may limit swift foxes. To test our hypothesis, we installed artificial escape dens in 3 spatially separated (treated) areas on the Rita Blanca National Grasslands in Dallam County, Texas, USA. From January 2002 to August 2004, we captured, radiocollared, and monitored 55 swift foxes. Annual swift fox survival in artificial escape-den—treated areas (Ŝ = 0.81) was higher than in untreated areas (Ŝ = 0.52, P = 0.07). Relative swift fox abundance was higher in treated than untreated areas in 2002 (Yates' χ2 = 4.61, P = 0.03) and in 2003 (Yates' χ2 = 4.70, P = 0.03) but not in 2004 (Yates' χ2 = 2.67, P = 0.10). However, recruitment rates were no different between treated and untreated areas in 2002 (Yates' χ2 = 0.21, P = 0.65) or 2003 (Yates' χ2 = 0.41, P = 0.52). Ninety-five percent fixed-kernel estimates of home-range sizes revealed no difference (P = 0.91) between treated and untreated areas, but swift foxes increased their distribution by moving into an area that had been unoccupied for at least 3 years before this study. Our results suggest that artificial escape dens contributed to increasing swift fox distributions in our study area.

CHARACTERISTICS OF SWIFT FOX DENS IN NORTHWEST TEXAS

Abstract The swift fox (Vulpes velox) was classified in 1995 as a candidate for listing under the Endangered Species Act. Since then, several studies have addressed survey methods for monitoring swift fox populations. The purpose of this paper is to assist field researchers in documenting the presence of swift foxes by identification of recently active den sites. We propose that swift foxes have unique external den characteristics that can be distinguished during aerial surveys. We collected data from 30 swift fox den complexes on both continuous rangeland and landscapes fragmented by cropland in northwest Texas. There were no differences in den characteristics between landscape types (P > 0.10). The number of openings per den ranged from 1 to 8 and had an average opening height of 20 cm. As number of openings increased, the maximum distance between openings also increased (r = 0.88, P < 0.001). One of the most distinguishing characteristics of swift fox dens was their dirt tailing. Of 74 den openings exa...

Multiple Scale Den Site Selection by Swift Foxes, &lt;em&gt;Vulpes velox&lt;/em&gt;, in Southeastern Colorado

Predation by Coyotes (Canis latrans) is a major source of mortality in Swift Fox (Vulpes velox) populations. Year-round den use by Swift Foxes is likely to be a predator avoidance strategy. Due to the importance of denning to Swift Fox ecology, we recorded den site selection of Swift Foxes in southeastern Colorado. Den site selection was recorded at two scales: microhabitat characteristics at the den and den placement within the home range. The number of den entrances, height and width of each entrance, aspect, hill position, slope, percent rock in soil, vegetative cover, and horizontal foliar density of 42 Swift Fox dens were examined during December 1999 – April 2000. This was compared to the same microhabitat characteristics at 42 random sites within Swift Fox home ranges to determine if Swift Foxes were using site characteristics according to their availability. Our results indicated that Swift Foxes were not highly selective of den sites based on the microhabitat characteristics evaluated in this study, although Swift Foxes selected areas of intermediate rock percentages. In addition, Swift Foxes were radio-tracked throughout the sample period and the location and frequency of use of known dens were recorded. Within the core area of home ranges, Swift Foxes used more dens (mean = 3.51 ± 1.70 (SD)), and had a higher frequency of use of dens (mean = 8.20 ± 6.01) than in the mid-range area (number of dens, mean = 0.90 ± 0.94; frequency, mean = 1.27 ± 2.12) and the boundary area (number of dens, mean = 0.34 ± 0.53; frequency, mean = 0.45 ± 0.93) of the home range. We discuss our results in terms of the importance of dens in facilitating escape from Coyotes. These results illustrate the need for examining den site selection at multiple scales to determine all selection factors, and to provide information useful for recovery and management efforts for this species.

Genetic and spatial structure within a swift fox population

Summary We incorporated spatial data on swift foxes (Vulpes velox) with genetic analysis to assess the influence of relatedness between individuals on their social and spatial ecology. We recorded the space use patterns of 188 radio‐collared swift foxes in south‐eastern Colorado from January 1997 to December 2000. One hundred and sixty‐seven foxes were also genotyped at 11 microsatellite DNA loci and the degree of relatedness between individuals was estimated. We described the genetic structure of the population by examining the relatedness of neighbours and the relationship between the spatial and genetic distance of all individuals. We found that close kin appeared to cluster within the population. Neighbours were significantly more related (mean R = 0·089 ± 0·01) than non‐neighbours (mean R = 0·003 ± 0·01; randomization test, P &lt; 0·0002). Female clusters were more extensive than male clusters. The degree of genetic relatedness among foxes was useful in explaining why foxes tolerated encroachment of their home ranges by neighbours; the more closely related neighbours were, the more home‐range overlap they tolerated (Mantel test, P = 0·0004). Foxes did not appear to orientate their home ranges to avoid neighbours and home ranges overlapped by as much as 54·77% (x = 14·13% ± 0·41). Neighbours also occasionally engaged in concurrent den sharing. Relatedness influenced the likelihood that an individual would inherit a newly vacated home range, with a mean relatedness of range inheritors to previous owners of 0·333 ± 0·074. Thus, the genetic structure of the population and interactions between kin were interrelated to space‐use patterns and social ecology of the swift fox.

A comparison of survey techniques for swift fox pups

Swift foxes (Vulpes velox) are one of the smallest and most den-dependent and nocturnal canids in North America (Egoscue 1979, Tannerfeldt et al. 2003)Though research concerning swift fox fecundity has been conducted, it is a difficult and arduous task because pups do not emerge from natal dens until they are weaned at 5-7 weeks of age (Egoscue 1979). Previous techniques for determining fecundity of swift foxes have included excavating the den and counting pre-emergent pups (Cutter 1958, Kilgore 1969) and visual counts of post-emergent pups (Covell 1992, Olson and Lindzey 2002, Schauster et al. 2002, Harrison 2003, Sovada et al. 2003). Visual counts are the most commonly reported technique for counting post-emergent swift fox pups (Covell 1992, Olson and Lindzey 2002, Schauster et al. 2002, Harrison 2003, Sovada et al. 2003). In this technique >1 concealed observers with binoculars or spotting scopes watch a female's den from a distance (usually >40 m) in the evening and morning hours during early summer, in an attempt to count the number of pups. Visual counts also have been effectively used with similar species such as the kit fox (Vulpes macrotis; Cypher et al. 2000, Koopman et al. 2000) and arctic fox (V.lagopus; Strand et al. 2000). Prior research concerning determination of preemergent pups has been highly invasive, as dens were excavated or disturbed via observer presence. As more advanced technology becomes available to researchers, less insidious means of obtaining data can be implemented. Recently, video probe systems have been used to document various cavity-nesting and burrowing animals such as red-cockaded woodpeckers (Picoides borealis; Richardson et al. 1999) and western burrowing owls (Athene cunicularia hypugea; Gervais et al. 2000). Night-vision devices have been used to enumerate migrating owls (Tyto alba,Aegolius acadicus,Asio otus, Asio flammeus, and Otus asio; Russell et al. 1991) and to observe the emergence of big brown bats (Eptesicus fuscus) from maternal colonies (Kirkwood and Cartwright 1993). Automated videography has been used to observe nests and index population abundance (York 1991, Kristan et al. 1996, Booms and Fuller 2003). Yet, none of this technology has been evaluated for use in swift fox research. Measuring fecundity is an essential component in examining demographics of any wildlife species. Information on litter sizes is necessary to understand the dynamics of swift fox populations. Yet, no pups were observed from preliminary efforts at visual counts of swift fox pups during our study. Thus, the objective of this study was to compare visual counts, night vision, a den-probe system, and an automated video monitoring system for counting swift fox pups.

ESTIMATION OF SWIFT FOX POPULATION SIZE AND OCCUPANCY RATES IN EASTERN COLORADO

Abstract The status of the swift fox (Vulpes velox) became a subject of controversy when a petition was submitted in 1992 to have it listed under the provisions of the Endangered Species Act. Colorado is believed to have one of the largest remaining populations of the species due to significant amounts of short-grass prairie habitat suitable for occupancy. In 1995, we initiated a survey in eastern Colorado to determine swift fox population size and presence or absence on 724.8×6.4 km2 grids trapped with 20 live traps. We drew trapping grids from a stratified random sample of grids plotted on 1:100,000 scale Gap vegetation maps of eastern Colorado. Of the grids sampled, 54% were from areas with 75% short-grass habitat. We captured 241 swift foxes (117 male, 121 female, and 3 undetermined) on 51 (71%) of the grids. We estimated a mean capture probability per night of an individual fox, weighted by number of grids and number of trapping occasions for each grid, as 0.234 (SE = 0.022). Highest capture and dete...

Ectoparasites of the swift fox in northwestern Texas.

Ectoparasites were collected from chemically immobilized swift foxes (Vulpes velox) in the Texas Panhandle (USA). Three species of fleas (Pulex irritans, Dactylopsylla percernis, and Euhoplopsyllus affinis) and one species of tick (Ixodes sculptus) were found. Pulex irritans was the only abundant ectoparasite; it occurred on all 23 foxes brushed in 1999-2000 and all but one of 34 hosts examined in 2000-01. Otherwise, this swift fox population had a depauperate ectoparasite fauna; the remainder of the ectoparasites only occurred on a few (< or =5%) of the hosts. Because of previous taxonomic confusion between P. irritans and the closely related P. simulans, the zoogeographic distribution of these two species in many areas of western North America needs to be verified. Apparently, only the human flea P. irritans occurs on wild canids in the Texas Panhandle. However, there are previous records of P. simulans on other carnivores in western and central Texas. Some of these specimens were reexamined, and their identifications were reconfirmed. Also, the recent literature on the controversial taxonomic status of these two flea species is reviewed. The male terminal aedeagal sexual apparatus is the only means currently available to separate P. irritans and P. simulans.