In its current distribution and abundance, the swift fox (Vulpes velox) has been significantly reduced from its historic range. A possible cause is competition with, and predation by, coyotes (Canis latrans). We investigated the level of spatial, temporal, and dietary resource use overlap between swift foxes and coyotes at the Pinon Canyon Maneuver Site in southeastern Colorado. We captured and radio-tracked 73 foxes and 24 coyotes from April 1997 to August 1998. We collected 10 832 and 5350 locations of foxes and coyotes, respectively. Overall, home-range sizes of foxes and coyotes were 7.6 ± 0.5 (mean ± SE) and 19.8 ± 1.9 km 2 , respectively. A high degree of interspecies spatial overlap was apparent, with fox home ranges being overlapped by coyote home ranges by as much as 100% and coyote sign (tracks and scats) being evident in all swift fox home ranges. There was no evidence of temporal avoidance of coyotes in fox movement patterns. Coyotes traveled significantly farther than foxes during diurnal hours; foxes spent the majority of diurnal hours in or on top of dens. Coyotes and foxes showed a high index of overlap for dietary resources, although some dietary partitioning was apparent. Swift foxes specialized in small prey, such as insects and rodents, while coyotes used greater proportions of large prey, such as lagomorphs and ungulates. Interference competition was evident, with 48% (12/25) of fox mortalities identified as confirmed or probable coyote-caused deaths. In each case, death occurred outside either the fox's home range or the 85% isopleth of that range, indicating that coyotes are more likely to attack a fox successfully when it is a substantial distance from a den. We propose that swift foxes are able to coexist with coyotes, owing to year-round den use and a degree of dietary partitioning.Résumé : La répartition et l'abondance du Renard véloce (Vulpes velox) ont subi une diminution importante au cours des années. Parmi les causes possibles, il faut mentionner la compétition et la prédation exercées par le Coyote (Canis latrans). Nous avons tenté de déterminer l'importance du chevauchement des ressources spatiales, temporelles et alimentaires des deux espèces à Pinon Canyon Maneuver Site, dans le sud-est du Colorado. Nous avons capturé et suivi par radiotélémétrie 73 renards et 24 coyotes d'avril 1997 à août 1999. Par la suite, nous avons repéré les renards 10 832 fois et les coyotes, 5350 fois. Dans l'ensemble, les domaines des renards ont été évalués à 7,6 ± 0,5 (moyenne ± erreur type) km 2 et ceux des coyotes à 19,8 ± 1.9 km². Nous avons mesuré un chevauchement interspécifique important de l'espace utilisé et les domaines des renards étaient couverts par ceux des coyotes parfois à 100%; nous avons trouvé des marques de la présence de coyotes (pistes, fèces) dans tous les domaines des renards. Les déplacements des renards ne permettent pas d'affirmer qu'il y a ségrégation temporelle des deux espèces. Les coyotes couvrent des distances significativement plus grandes que les renards durant les h...

In its current distribution and abundance, the swift fox (Vulpes velox) has been significantly reduced from its historic range. A possible cause is competition with, and predation by, coyotes (Canis latrans). We investigated the level of spatial, temporal, and dietary resource use overlap between swift foxes and coyotes at the Pinon Canyon Maneuver Site in southeastern Colorado. We captured and radio-tracked 73 foxes and 24 coyotes from April 1997 to August 1998. We collected 10 832 and 5350 locations of foxes and coyotes, respectively. Overall, home-range sizes of foxes and coyotes were 7.6 * 0.5 (mean i SE) and 19.8 * 1.9 km2, respectively. A high degree of interspecies spatial overlap was apparent, with fox home ranges being overlapped by coyote home ranges by as much as 100% and coyote sign (tracks and scats) being evident in all swift fox home ranges. There was no evidence of temporal avoidance of coyotes in fox movement patterns. Coyotes traveled significantly farther than foxes during diurnal hours; foxes spent the majority of diurnal hours in or on top of dens. Coyotes and foxes showed a high index of overlap for dietary resources, although some dietary partitioning was apparent. Swift foxes specialized in small prey, such as insects and rodents, while coyotes used greater proportions of large prey, such as lagomorphs and ungulates. Interference competition was evident, with 48% (12125) of fox mortalities identified as confirmed or probable coyote-caused deaths. In each case, death occurred outside either the fox's home range or the 85% isopleth of that range, indicating that coyotes are more likely to attack a fox successfully when it is a substantial distance from a den. We propose that swift foxes are able to coexist with coyotes, owing to year-round den use and a degree of dietary partitioning. RCsumC : La rkpartition et l'abondance du Renard vCloce (Vulpes velox) ont subi une diminution importante au cours des annCes. Parmi les causes possibles, il faut mentionner la compCtition et la prCdation exercCes par le Coyote (Canis latrans). Nous avons tent6 de dCterminer l'importance du chevauchement des ressources spatiales, temporelles et alimentaires des deux esp6ces i Pinon Canyon Maneuver Site, dans le sud-est du Colorado. Nous avons capturk et suivi par radiotClCmCtrie 73 renards et 24 coyotes d'avril 1997 i aoQt 1999. Par la suite, nous avons repCrC les renards 10 832 fois et les coyotes, 5350 fois. Dans l'ensemble, les domaines des renards ont kt6 CvaluCs i 7,6 * 0,5 (moyenne * erreur type) km2 et ceux des coyotes i 19,8 * 1.9 km2. Nous avons mesurd un chevauchement interspdcifique important de l'espace utilisC et les domaines des renards Ctaient couverts par ceux des coyotes parfois i 100%; nous avons trouvC des marques de la prCsence de coyotes (pistes, fkces) dans tous les domaines des renards. Les dCplacements des renards ne permettent pas d'affirmer qu'il y a sCgrCgation temporelle des deux espkces. Les coyotes couvrent des distances significativement plus grandes que les renards durant les heu...

Activity patterns in animals are influenced by a number of factors, including the animal's physiological adaptations, prey availability and distribution, and disturbances caused by predators and humans. We compared coyote (Canis latrans) activity patterns estimated using radio-tracking locations between 1983 and 1988 with those documented between 1996 and 1997 on the Pinon Canyon Maneuver Site, in southeastern Colorado. We tested the hypothesis that changes in the type of disturbance experienced by coyotes would result in changes in their activity patterns. Disturbance experienced by the coyote population studied during 1983-1988, included >50 years of intense exploitation (shooting and trapping by ranchers) and intensive removal efforts using aerial gunning. In contrast, coyotes tracked during 1996-1997 experienced some periodic disturbance from army maneuvers occurring in the area, but were not exposed to any direct form of persecution (e.g., shooting). From August 1983 to July 1988, 49 coyotes (26 males and 23 females) were tracked for >2400 h using radiotelemetry. From April 1996 to August 1997, 22 coyotes (12 males and 10 females) were tracked for >950 h. The average rate of diurnal movement of the coyotes in the 1996-1997 field study (T = 0.97 km/h) was significantly higher than that of the coyotes in the 1983-1988 field study (T = 0.68 km/h). This occurred despite no significant increase in the overall (24 h) rate of movement between the two field studies. Estimates of prey use by the coyotes in both field studies were obtained, to test an alternate hypothesis that prey switching might explain the changes in coyote movement patterns. However, there was no significant difference between the frequency of occurrence of diurnally versus nocturnally active mammalian prey species in the diets of coyotes in any season or overall between the 1983-1988 and 1996-1997 field studies. This study demonstrated that coyote activity patterns can be influenced by the type of disturbance experienced by the animal. A coyote population that had historically been exposed to human persecution shifted to higher levels of diurnal activity when exploitation ceased. RCsumC : L'activitC des animaux est influencCe par plusieurs facteurs, notamment les adaptations physiologiques de l'animal, la disponibilitk et la rkpartition des proies et les perturbations crCCes par les prCdateurs et les humains. Nous

Swift foxes (Vulpes velox) were once distributed across most of the shortgrass prairie of North America. The arrival of settlers and the concurrent loss of habitat, trapping, incidental poisoning, and shooting brought about a decline in its numbers until the swift fox remained only in the southern part of its historic range. A current understanding of swift fox population ecology is important to management and conservation efforts. We examined the population ecology of swift foxes on a native shortgrass prairie ecosystem in southeastern Colorado. From January 1997 to December 1998 we investigated home-range size and space use, spatial overlap, dispersal patterns, survival rates, and reproduction using a sample of 90 (42 males, 48 females) radio-collared foxes. Home ranges were largest (9.4 ± 4.9 km 2 ) and spatial overlap was greatest using nighttime locations when foxes were active, while daytime locations indicated that the use of dens was exclusive among social units, and space use (2.8 ± 2.2 km 2 ) was reduced during the day. Among resident foxes, survival rates were higher for adults than for juveniles. For dispersing foxes, adults that dispersed had higher survival rates than juvenile dispersers. Social units ranged in size from 2 to 4 foxes. About 58% of the social units produced pups; litter size averaged 2.4 pups at den emergence. Among the surviving pup cohort, some pups were philopatric, some dispersed long distances, while others dispersed to neighboring territories. Swift fox density was negatively associated with both coyote (Canis latrans) and lagomorph abundance but positively correlated with rodent abundance.Résumé : L'aire de répartition du renard véloce (Vulpes velox) s'étendait jadis à toute la prairie à herbes courtes de l'Amérique du Nord. L'arrivée des colons et, en conséquence, la perte d'habitats, le trappage, les empoisonnements accidentels et la chasse, ont réduit les densités du renard au point où il ne survit plus que dans la partie sud de son aire traditionnelle. Pour des fins de gestion et de conservation, il importe de connaître l'écologie actuelle de l'espèce. Nous avons donc étudié l'écologie d'une population d'un écosystème naturel de prairie à herbes courtes du sud-est du Colorado. Un échantillon de 90 (42 males : 48 femelles) renards munis de colliers radio-émetteurs nous a permis, de janvier 1997 à décembre 1998, de déterminer la taille du domaine vital, l'utilisation de l'espace, les chevauchements spatiaux, les patterns de dispersion, les taux de survie et la reproduction. La taille des domaines (9,4 ± 4,9 km 2 ) et les recouvrements de domaines étaient aximaux lorsque calculés à partir des repérages de nuit au moment où les renards étaient actifs; les repérages de jour indiquaient que l'utilisation des terriers était réservée exclusivement à chacun des groupes sociaux et que l'utilisation de l'espace (2,8 ± 2,2 km 2 ) était réduite durant le jour. Chez les renards résidants, les taux de survie étaient plus élevés chez les adultes que chez les jeunes. Les adultes...

Kitchen, Ann M.; Gese, Eric M.; Waits, Lisette P.; Karki, Seija M.; and Schauster, Edward R., "Genetic and spatial structure within a swift fox population" (2005 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 southeastern 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. 2. 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 < 0·0002). Female clusters were more extensive than male clusters. 3. 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. 4. 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.