Morbidity-mortality factors and survival of an urban coyote population in Arizona

The health of coyotes (Canis latrans) in urban areas has not been studied. Our objectives were to assess the health of coyotes in Tucson (Arizona, USA) by determining the prevalence of antibodies to selected pathogens, estimating survival rates, and identifying sources of mortality. We drew blood from 22 coyotes to evaluate the prevalence of heartworm (Dirofilaria immitis) antigens, and antibodies to canine distemper virus (CDV), infectious canine hepatitis (ICH), canine parvovirus (CPV), and seven serovars of Leptospira interrogans. We trapped and radiocollared 19 coyotes to determine survival rates. We performed necropsies on 19 coyotes to quantify their general health, the presence of internal and external parasites, and causes of mortality. No coyotes tested positive for heartworm antigens. The prevalence of antibody to CDV, ICH, and CPV was 27, 50, and 100%, respectively. Twenty-seven percent of coyotes tested positive for one of five serovars of L. interrogans. The diseases for which coyotes in Tucson possessed antibodies appear to be enzootic in the population. The annual survival rate of coyotes was 0.72. Eleven necropsied coyotes were killed by cars, five coyotes were hit by cars, two were killed by a trapper, and the cause of death for one coyote was unknown. Coyotes in Tucson appear to be exposed to the viral, bacterial, and parasitic infections common in many coyote populations, but humans are the major source of mortality.     

Traumatic, degenerative, and developmental lesions in wolves and coyotes from Saskatchewan.

A retrospective review was done of traumatic and osseous lesions in 241 wolves (Canis lupus) and 316 coyotes (Canis latrans) necropsied at the University of Saskatchewan between 1971 and 1990. Most lesions were the result of interspecific conflict. The most frequently occurring lesion in wolves was fracture of one or more bones, primarily ribs. Lesions were healed in most cases and appeared to be compatible with injuries caused by prey animals. One wolf, found dead, died as a result of thoracic trauma. Limb and skull fractures were less common. Fractures were uncommon in coyotes. The most frequent injuries in coyotes were related to gunshot wounds. Four coyotes had been killed but not eaten by wolves. One wolf had been killed and another attacked by wolves. Porcupine (Erethizon dorsatum) quills contributed to the death of a wolf and two coyotes. Degenerative joint disease, involving the spinal column and limb joints, was found in a few individuals of both species. A coyote had severe anomalies of the spinal column and a wolf had anomalous external genitalia.     

Serologic survey for canine infectious diseases among sympatric swift foxes (Vulpes velox) and coyotes (Canis latrans) in southeastern Colorado

Swift foxes (Vulpes velox) and coyotes (Canis latrans) are sympatric canids distributed throughout many regions of the Great Plains of North America. The prevalence of canid diseases among these two species where they occur sympatrically is presently unknown. From January 1997 to January 2001, we collected blood samples from 89 swift foxes and 122 coyotes on the US Army Pi?on Canyon Maneuver Site, Las Animas County, SE Colorado (USA). Seroprevalence of antibodies against canine parvovirus (CPV) was 71% for adult (> 9 mo old) and 38% for juvenile (< or = 9 mo old) swift foxes. Adult (<1 yr old) and juvenile (<1 yr old) coyotes had a seroprevalence for CPV of 96% and 78%, respectively. Presence of antibodies against canine distemper virus (CDV) was 5% for adult foxes and 0% for juvenile foxes. Seroprevalence of CDV was 46% for adult coyotes and 18% for juvenile coyotes. No swift foxes had canine adenovirus (CAV) antibodies, whereas 81% and 63% of adult and juvenile coyotes, respectively, had antibodies for CAV. Seroprevalence of antibodies against Yersinia pestis was 68% among adult foxes and 34% among juvenile swift foxes. Seroprevalence of Y. pestis antibodies was 90% and 70% for adult and juvenile coyotes, respectively. No swift foxes had antibodies against Francisella tularensis, whereas seroprevalence was 4% among both adult and juvenile coyotes. Antibodies against CPV and plague were common in both species, whereas antibodies against CDV and CAV were more prevalent in coyotes compared to swift foxes.     

Experimental infection of adult and juvenile coyotes with domestic dog and wild coyote isolates of Hepatozoon americanum (Apicomplexa: Adeleorina)

Each of five adult and four juvenile coyotes (Canis latrans) was exposed to an oral dose of 50 Hepatozoon americanum oocysts recovered from Amblyomma maculatum ticks that previously fed on either naturally infected domestic dogs (Canis familiaris) or naturally infected wild coyotes. All coyotes exposed to H. americanum became infected, regardless of isolate source, and all exhibited mild to moderate clinical disease that simulated American canine hepatozoonosis in naturally infected dogs. At 100 days postexposure, parasitemia was greater in juvenile than adult coyotes (0.9% and 0.3%, respectively); radiographic imaging of femurs revealed moderate exostosis in all juveniles and mild to moderate new bone growth in four of five (80%) adult coyotes. Gross postmortem analysis of bone lesions demonstrated variation between age groups of coyotes but not between isolates of H. americanum. Microscopic evaluation of skeletal muscle revealed that parasite-induced lesions were significantly more numerous (t = 5.0, df = 7, P = 0.001) in juvenile than adult coyotes. Results of this study indicate that juvenile and adult coyotes are equally susceptible to experimental infection with H. americanum isolated from domestic dog and wild coyote sources. The age of coyotes at the time of exposure, and possibly the number of H. americanum oocysts ingested, might influence morbidity and mortality, but it appears that both adult and juvenile coyotes could be reservoirs of H. americanum.     

Parasitic infection of Filaroides osleri, Capillaria aerophila and Spirocera lupi in coyotes from the Southwestern United States

A total of 181 coyotes (Canis latrans) was examined for helminth parasites Filaroides osleri, Capillari aerophila, and Spirocerca lupi. Coyote carcasses were obtained from Kansas, western Oklahoma-northern Texas, Colorado, New Mexico, Arizona and southern California. Cysts of F. osleri were present in the trachea or bronchial division in 39 (22%) coyotes. C. aerophila were present in only 7 (4%) coyotes. S. lupi lesions were present in the aorta of 59 (33%) coyotes. Esophageal infections of S. lupi were found in only 4 of 142 (3%) coyotes. F. osleri, C. aerophila and S. lupi infections were more prevalent in western Oklahoma-northern Texas, low in southern Arizona-California, and absent in northern Arizona.     

Diseases, parasites and survival of coyotes in south-central Georgia.

Serologic testing, radio-telemetry and post-mortem diagnostic evaluations were used to investigate survival and causes of mortality among 17 coyotes (Canis latrans) in south-central Georgia (USA). Prevalence of canine heartworm (Dirofilaria immitis) microfilariae was lower (P = 0.057) among fall-captured (22%) than among winter-captured (75%) coyotes. Prevalence of heartworm was higher among adults than juveniles in the fall, but no significant difference was detected between animals captured in winter. Antibodies were found against canine parvovirus (65%), canine parainfluenza virus (59%), infectious canine hepatitis virus (41%), and Toxoplasma gondii (18%). Antibodies were not found to Brucella canis, canine coronavirus, five serovars of Leptospira interrogans, or canine distemper virus. Seroprevalence of canine parvovirus was lower (P = 0.009) among fall-captured animals (33%) than winter-captured animals (100%). The Kaplan-Meier estimate of annual survival was 0.500 for all animals. Juvenile survival did not differ (P = 0.79) from adult survival, but male survival (S = 0.217) was lower (P = 0.11) than female survival (S = 0.804). Two of nine (22%) mortalities were human-caused, one was due to concurrent canine parvovirus and canine distemper virus infections, one animal died of trauma, two were considered natural mortalities of unknown cause, and no cause of death could be determined for the remaining three animals. Natural mortality may be significant for coyotes in south-central Georgia, although there was no apparent link between exposure to pathogens and the animals' subsequent fate in our small sample.     

Influence of the urban matrix on space use of coyotes in the Chicago metropolitan area

Expansion of the coyote’s (Canis latrans) distribution in North America has included most urban areas. Concerns for human safety have resulted in the need to understand the spatial relationship between humans and coyotes in urban landscapes. We examined the space use of coyotes with varying degrees of urban development in the Chicago metropolitan area, IL, USA, between March 2000 and December 2002. We compared home-range size, land use, and habitat use of 41 radio-collared coyotes (5 coyotes residing in developed areas, 29 in less-developed areas, and 7 in a matrix of developed and less-developed areas). The partitioning of coyotes into groups based on their level of exposure to urban development allowed us to examine if differences in use of land types by coyotes was evident in our study area. Coyotes in developed areas had home ranges twice the size of animals in less-developed areas. Nonurban habitats were used by all coyotes in the study area, while urban land was avoided. Coyotes in developed areas had large home ranges and high amounts of urban land in their range, but preferred nonurban habitat. This required the coyotes to travel through a matrix of urban land, thus encountering human activity and possibly increasing the risk of conflict with humans. However, coyotes in developed areas avoided crepuscular times when human activity was highest, suggesting that coyotes in developed areas may reduce conflicts with humans by traveling through the matrix of urban land late at night when the risk of contact with humans is lowest. Coyotes in less-developed areas were less affected by human activity at night and likely posed less risk to humans.     

Brucella abortus in coyotes. I. A serologic and bacteriologic survey in eastern Texas.

Prevalence of Brucella abortus serum antibodies in coyotes from east central Texas was determined by the buffered Brucella antigen (card test), rivanol, standard agglutination tube, and cold complement fixation tube tests. Eighteen percent (9 of 51) of the coyotes were positive serologically. B. abortus biotype 1 was isolated from various tissues from 7 of 43 coyotes by bacteriologic culture. Congenital transmission was found.     

Y‐chromosome evidence supports asymmetric dog introgression into eastern coyotes

Hybridization has played an important role in the evolutionary history of Canis species in eastern North America. Genetic evidence of coyote–dog hybridization based on mitochondrial DNA (mtDNA) is lacking compared to that based on autosomal markers. This discordance suggests dog introgression into coyotes has potentially been male biased, but this hypothesis has not been formally tested. Therefore, we investigated biparentally, maternally, and paternally inherited genetic markers in a sample of coyotes and dogs from southeastern Ontario to assess potential asymmetric dog introgression into coyotes. Analysis of autosomal microsatellite genotypes revealed minimal historical and contemporary admixture between coyotes and dogs. We observed only mutually exclusive mtDNA haplotypes in coyotes and dogs, but we observed Y‐chromosome haplotypes (Y‐haplotypes) in both historical and contemporary coyotes that were also common in dogs. Species‐specific Zfy intron sequences of Y‐haplotypes shared between coyotes and dogs confirmed their homology and indicated a putative origin from dogs. We compared Y‐haplotypes observed in coyotes, wolves, and dogs profiled in multiple studies, and observed that the Y‐haplotypes shared between coyotes and dogs were either absent or rare in North American wolves, present in eastern coyotes, but absent in western coyotes. We suggest the eastern coyote has experienced asymmetric genetic introgression from dogs, resulting from predominantly historical hybridization with male dogs and subsequent backcrossing of hybrid offspring with coyotes. We discuss the temporal and spatial dynamics of coyote–dog hybridization and the conditions that may have facilitated the introgression of dog Y‐chromosomes into coyotes. Our findings clarify the evolutionary history of the eastern coyote.     

Resource utilization and interspecific relations of sympatric bobcats and coyotes

We used scat analysis and radiotelemetry to characterize use of foods and habitats by sympatric bobcats and coyotes, and evaluated these in the context of spatial and temporal relationships to assess the potential for, and evidence of, interspecific competition. Bobcats and coyotes exhibited broad and overlapping diets. However, diets of the two predators differed in the relative contributions of small and large prey, with bobcats consuming relatively more rodent and lagomorph biomass and coyotes consuming relatively more ungulate biomass. Consumption among rodent prey species was highly correlated between bobcats and coyotes, indicating no evidence of prey partitioning within this group. Habitat selection by the two predators differed slightly at the landscape scale but not within home ranges. Bobcats and coyotes occupied small, overlapping home ranges, such that the likelihood of interspecific encounters (direct or indirect) was high. Bobcats displayed slight avoidance of overlapping coyote core areas during coyote reproductive seasons (winter and spring), when coyotes are typically most territorial (toward conspecifics), but displayed slight attraction during times of year when coyotes were not engaged in reproductive activities. Relative to coyotes, which were strongly nocturnal, diel activity patterns of bobcats were more diurnal and variable. However, activity patterns were not inversely correlated. Overall, these predators appeared to use resources independently and we found little evidence of negative interactions. Differences in resource use by bobcats and coyotes appeared to relate to fundamental niche differences as opposed to competition-related resource partitioning.     

Geographic patterns in morphometric and genetic variation for coyote populations with emphasis on southeastern coyotes

Prior to 1900, coyotes (Canis latrans) were restricted to the western and central regions of North America, but by the early 2000s, coyotes became ubiquitous throughout the eastern United States. Information regarding morphological and genetic structure of coyote populations in the southeastern United States is limited, and where data exist, they are rarely compared to those from other regions of North America. We assessed geographic patterns in morphology and genetics of coyotes with special consideration of coyotes in the southeastern United States. Mean body mass of coyote populations increased along a west‐to‐east gradient, with southeastern coyotes being intermediate to western and northeastern coyotes. Similarly, principal component analysis of body mass and linear body measurements suggested that southeastern coyotes were intermediate to western and northeastern coyotes in body size but exhibited shorter tails and ears from other populations. Genetic analyses indicated that southeastern coyotes represented a distinct genetic cluster that differentiated strongly from western and northeastern coyotes. We postulate that southeastern coyotes experienced lower immigration from western populations than did northeastern coyotes, and over time, genetically diverged from both western and northeastern populations. Coyotes colonizing eastern North America experienced different selective pressures than did stable populations in the core range, and we offer that the larger body size of eastern coyotes reflects an adaptation that improved dispersal capabilities of individuals in the expanding range.     

Greater consumption of protein‐poor anthropogenic food by urban relative to rural coyotes increases diet breadth and potential for human–wildlife conflict

Reports of encounters between people and generalist urban‐adapted carnivores are increasing around the world. In North America, coyotes Canis latrans are among the carnivores that appear to be especially capable of incorporating novel anthropogenic food types, including those found in cities. Consuming anthropogenic food may benefit coyotes by increasing their dietary diversity, but it may also lead to increased interactions and conflicts with humans. To test these hypotheses, we compared the diets of urban and rural coyotes from two urban and three rural sites spanning 32 200 km² in Alberta, Canada. We analyzed scat samples to calculate diet diversity at the level of both individuals (species per scat) and populations (Shannon index) and to determine the frequency of anthropogenic food consumption. We complemented this comparison with stable isotope analyses of hair samples taken from individual urban and rural coyotes that were or were not reported by the public for repeatedly visiting backyards and schoolyards during the day. Relative to rural coyotes, urban coyotes had more diverse diets at the level of both individuals and populations, consumed anthropogenic food more often, and animals less often, than rural coyotes. Although urban coyotes assimilated more anthropogenic food than the rural coyotes overall, the urban coyotes reported for conflict assimilated less protein and were more likely to be diseased. Our results suggest that processed anthropogenic food may contribute to the success of urban coyotes, but does not entirely correlate with conflict. Instead, some seemingly innocuous, but low‐protein food sources such as bird feeders, compost, and cultivated fruit trees may contribute disproportionately to encounters with people for coyotes and other urban‐adapted opportunistic carnivores.     

The influence of snow on lynx and coyote movements: does morphology affect behavior?

Summary We studied sympatric lynx (Lynx canadensis) and coyotes (Canis latrans) to assess how morphological disadvantages to locomotion over snow affected movement patterns. Both species are of similar size and mass, but the feet of lynx are much larger, and coyotes were found to have 4.1–8.8 times the foot-load (ratio of body mass to foot area) of lynx. This resulted in greater mean sinking depths of coyote limbs, although the magnitude of the difference was less than that in foot-load. Coyotes exhibited stronger use of behavioral patterns that reduced negative effects of snow on movements. Coyotes were most abundant at low elevations where snow was shallow, whereas lynx were mostly at higher elevations. Coyotes also used areas at both elevations where snow was shallower than average, while lynx used areas where snow was deeper. further, both species used travel routes where snow was shallower than it was near the track. Coyotes traveled on harder snow and used trails more frequently, thereby tending to reduce sinking depths to those similar to lynx. The behavioral repertoire of coyotes reduced the morphological advantage of large feet possessed by lynx; however, overall sinking depths were still greater in coyotes. Snowshoe hares (Lepus americanus) were the main prey of both species, and their foot-load was less than that of either predator. Hare kills by coyotes occurred after fewer bounds than did those by lynx, and the large difference between foot-loads of both species of predators may have forced coyotes to ambush rather than chase hares, as did lynx.     

Agouti sequence polymorphisms in coyotes, wolves and dogs suggest hybridization

Domestic dogs have been shown to have multiple alleles of the Agouti Signal Peptide (ASIP) in exon 4 and we wished to determine the level of polymorphism in the common wild canids of Canada, wolves and coyotes, in comparison. All Canadian coyotes and most wolves have banded hairs. The ASIP coding sequence of the wolf did not vary from the domestic dog but one variant was detected in exon 4 of coyotes that did not alter the arginine at this position. Two other differences were found in the sequence flanking exon 4 of coyotes compared with the 45 dogs and 1 wolf. The coyotes also demonstrated a relatively common polymorphism in the 3' UTR sequence that could be used for population studies. One of the ASIP alleles (R96C) in domestic dogs causes a solid black coat color in homozygotes. Although some wolves are melanistic, this phenotype does not appear to be caused by this same mutation. However, one wolf, potentially a dog-wolf hybrid or descendant thereof, was heterozygous for this allele. Likewise 2 coyotes, potentially dog-coyote or wolf-coyote hybrid descendants, were heterozygous for the several polymorphisms in and flanking exon 4. We could conclude that these were coyote-dog hybrids because both were heterozygous for 2 mutations causing fawn coat color in dogs.     

Behavioural budgeting by wild coyotes: The influence of food resources and social organization

Daytime behavioural budgets of coyotes (Canis latrans) living in the Grand Teton National Park, Jackson, Wyoming, were analysed in order to determine how activity patterns were influenced by food resources and social organization. In winter, coyotes rested more and hunted less than in other seasons. Pack-living coyotes rested more and travelled less than resident pairs or solitary residents or transients during winter months when the major food resource was ungulate (predominantly elk, Cervus canadensis) carrion. A mated female living in a pack rested significantly more and travelled significantly less than a mated female living only with her mate (as a resident pair) during winter. We predict that in times of food shortage, pack-living coyotes, and particularly reproductive females, might be at an advantage when compared to resident pairs and solitary individuals.     

Microbiomes in Canidae

Because of their range expansion across North America, coyotes (Canis latrans) now occur sympatrically with numerous other predator species, including red foxes (Vulpes vulpes). This raises several interesting ecological questions, including if and how sympatry affects the diet and gut microbiomes of coyotes and red foxes. We examined the gut microbiomes of sympatric populations of coyotes and red foxes within two different National Parks in Virginia, USA, that differ in land use, vegetation, and anthropogenic disturbance: Prince William Forest Park (PRWI) and Manassas National Battlefield Park (MANA). From 2012 to 2017, scat samples from PRWI and MANA were collected and analyzed. Polymerase chain reaction (PCR) amplification of a region of the mitochondrial cytochrome‐b gene followed by restriction enzyme digestion of the PCR product was used to determine the origin of each scat sample. Next‐Generation DNA sequencing of a hypervariable 16S rRNA gene region was used to determine gut microbiome information about the scat samples. There was no evidence for a difference between the gut microbiomes of red foxes in either location, or for a difference between the gut microbiomes of red foxes at either location and coyotes at the location with lower human disturbance, PRWI. However, the gut microbiomes of coyotes at the location with higher anthropogenic disturbances, MANA, revealed a marked change from those found in red foxes at either location and from those in coyotes at the location with lower disturbances. The gut microbiomes of coyotes subjected to greater human impact may provide evidence of dysbiosis, indicative of increased physiological stress and reduced health. We discuss our observations in the context of understanding anthropogenic impacts on coyote and red fox interactions. Our results suggest that physiological stress in the form of human disturbance may play an important role in the composition of the gut microbiome of coyotes, which can affect their overall health.     

Serologic and molecular evidence of Ehrlichia spp. in coyotes in California

In order to determine the role of coyotes in the epidemiology of granulocytic and monocytic ehrlichial agents in California (USA), we tested 149 serum samples for antibodies against Ehrlichia equi, E. risticii, and E. canis, using an indirect immunofluorescent antibody test. Polymerase chain reaction (PCR) assay was used to survey for the presence of members of the E. phagocytophila genogroup, E. risticii and E. canis in blood samples of 95 coyotes. Sixty-eight (46%) samples were seropositive for E. equi, two (1%) for E. risticii and none of the samples had antibodies reactive to E. canis. Two and one coyote were positive for E. risticii and members of the E. phagocytophila genogroup by PCR assay, respectively. In contrast, the 95 samples were negative for E. canis by PCR. Ninety-five percent of the 68 E. equi seropositive coyotes and the one coyote PCR positive for members of the E. phagocytophila genogroup originated from a coastal area. However, the two E. risticii seropositive coyotes and the two coyotes PCR positive for E. risticii were from northern California. Sequence analysis of the three amplified PCR products revealed the agent to be similar in two coyotes to the sequences of E. risticii from horses originating from northern California and identical in one coyote to the agent of human granulocytic ehrlichiosis and E. equi from California. Thus, coyotes are exposed to granulocytic ehrlichiae and E. risticii and may play a role in the epidemiology of these ehrlichial agents in California.     

Does interference competition with wolves limit the distribution and abundance of coyotes?

Interference competition with wolves Canis lupus is hypothesized to limit the distribution and abundance of coyotes Canis latrans, and the extirpation of wolves is often invoked to explain the expansion in coyote range throughout much of North America. We used spatial, seasonal and temporal heterogeneity in wolf distribution and abundance to test the hypothesis that interference competition with wolves limits the distribution and abundance of coyotes. From August 2001 to August 2004, we gathered data on cause-specific mortality and survival rates of coyotes captured at wolf-free and wolf-abundant sites in Grand Teton National Park (GTNP), Wyoming, USA, to determine whether mortality due to wolves is sufficient to reduce coyote densities. We examined whether spatial segregation limits the local distribution of coyotes by evaluating home-range overlap between resident coyotes and wolves, and by contrasting dispersal rates of transient coyotes captured in wolf-free and wolf-abundant areas. Finally, we analysed data on population densities of both species at three study areas across the Greater Yellowstone Ecosystem (GYE) to determine whether an inverse relationship exists between coyote and wolf densities. Although coyotes were the numerically dominant predator, across the GYE, densities varied spatially and temporally in accordance with wolf abundance. Mean coyote densities were 33% lower at wolf-abundant sites in GTNP, and densities declined 39% in Yellowstone National Park following wolf reintroduction. A strong negative relationship between coyote and wolf densities (beta = -3.988, P < 0.005, r(2) = 0.54, n = 16), both within and across study sites, supports the hypothesis that competition with wolves limits coyote populations. Overall mortality of coyotes resulting from wolf predation was low, but wolves were responsible for 56% of transient coyote deaths (n = 5). In addition, dispersal rates of transient coyotes captured at wolf-abundant sites were 117% higher than for transients captured in wolf-free areas. Our results support the hypothesis that coyote abundance is limited by competition with wolves, and suggest that differential effects on survival and dispersal rates of transient coyotes are important mechanisms by which wolves reduce coyote densities.     

Serological responses of coyotes to two commercial rabies vaccines.

Between August 1993 and September 1994 we documented serological responses of coyotes (Canis latrans) vaccinated with two commercial rabies vaccines licensed for use in domestic dogs. Serologic responses were documented by testing for rabies virus neutralizing antibodies with the rapid fluorescent focus inhibition test (RFFIT) at 30, 90, 180, 270, and 365 days post-vaccination. All coyotes vaccinated with Imrab 3 (Rhone-Merieux, Inc.), and 75% of those vaccinated with Dura-Rab 3 (Immunovet, Inc.) seroconverted, as evidenced by the presence of antirabies antibody titers > or = 1:5 in one or more of the five post-vaccination samples. The percent of coyotes showing a titer > or = 1:5 was generally greater and titer levels appeared higher and more persistent among animals vaccinated with Imrab 3 than Dura-Rab 3. Presence of titers via RFFIT tests demonstrates the antibodies produced in coyotes by these rabies vaccines functionally bind and neutralize rabies virus in vitro, but these results do not constitute a demonstration of protection required for licensure for use in coyotes.     

Coyote movements and social structure along a cryptic population genetic subdivision

A recent region-wide study determined that the central California coyote (Canis latrans) population was genetically subdivided according to habitat bioregions, supporting the hypothesis that coyotes exhibit a dispersal bias toward their natal habitat type. Here, we further investigated this hypothesis using radio-collared coyotes captured on a 150-km(2) study site on the border of (i.e. overlapping) two bioregions (Great Valley and Cascade Mountains). As predicted, most coyotes were assigned (based on a priori genetic criteria) to genetic clusters corresponding to one of these two bioregions. All of those assigned to the Great Valley genetic cluster were caught in (and for the most part, remained in) the Great Valley bioregion. However, contrary to expectations, the coyotes assigned to the Cascades genetic cluster occurred commonly in both bioregions. Nearly all resident individuals on the study site, regardless of the particular bioregion, were assigned to the Cascades genetic cluster, whereas a sizable fraction of nonresident (transient or dispersing) coyotes caught in the Great Valley bioregion were assigned to the Great Valley cluster. Even among resident coyotes, interrelatedness of packs was greater within than between bioregions, and packs with territories overlapping both bioregions were more closely related to those with territories completely within the Cascades bioregion than territories completely within the Great Valley bioregion. Finally, direct estimates indicated that gene flow was twice as high from the Cascades bioregion to the Great Valley bioregion than in the reverse direction. Collectively, these findings reveal the anatomy of the genetic subdivision as beginning abruptly at the bioregion boundary and ending diffusely within the Great Valley bioregion.