Eric M. Gese

Coyotes and recolonizing wolves: social rank mediates risk-conditional behaviour at ungulate carcasses

Wolf, Canis lupus, recolonization of the Greater Yellowstone Ecosystem provides a rare opportunity to identify behaviours facilitating coexistence between sympatric canids. We investigated interactions between coyotes, Canis latrans, and recolonizing wolves at ungulate carcasses in Montana’s Madison Range. We used a field-experimental study design consisting of a two-level carcass treatment (wolf presence, wolf absence) to assess factors influencing coyote risk assessment, carrion consumption and aggressive encounters with wolves. Socially dominant coyotes (alphas and betas) responded to wolf presence by increasing the proportion of time spent vigilant while scavenging. Vigilance behaviour was more pronounced when scavenging closer to structurally complex vegetation where lateral occlusion inhibited the ability of coyotes to scan for, and possibly escape from, returning wolves. Despite greater time spent vigilant, alpha coyotes consumed the greatest amount of carrion biomass by feeding on carcasses in earlier stages of consumption when organs and large muscle tissues were still present. This finding suggests that alpha coyotes might trade off greater risk for higher-quality food items. Coyotes would aggressively confront wolves: numerical advantage by coyotes and the stage of carcass consumption were influential in determining whether coyotes were able to displace wolves from carcasses. Coyotes relied on a gradient of risk-sensitive behaviours, ranging from elevated vigilance to aggressive confrontation, to manage risk associated with wolf presence. Identification of these behaviours, and their sensitivity to numeric and social factors, is an important step in elucidating mechanisms of resource partitioning in social canids.

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.

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

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

Territory fidelity, space use, and survival rates of wild coyotes following surgical sterilization

Sterilization of wild canids is being used experimentally in many management applications. Few studies have clearly demonstrated vasectomized and tubal-ligated canids will retain pair-bonding and territorial behaviors. We tested whether territory fidelity, space use, and survival rates of surgically sterilized coyote (Canis latrans) packs were different from sham-operated coyote packs. We captured and radio-collared 30 coyotes in December 2006. Sixteen of these animals were sterilized via vasectomy or tubal ligation, and 14 were given sham-surgeries (i.e., remained intact). We monitored these animals using telemetry and visual observations through 2 breeding seasons and 1 pup-rearing season from December 2006 to March 2008. Mean pack size was not significantly different between sterile and intact coyote packs. We found no difference in home range size between sterile and intact coyotes. We found differences in home range and core area overlap between sterile and intact coyote packs in some seasons; however, this difference may have existed prior to sterilization. Home range fidelity was not significantly different between sterile and intact coyotes. All coyotes had higher residency rates during the breeding season, with no differences between sterile and intact coyotes. Survival rates were correlated with biological season, but there were no differences in survival rates between sterile and intact coyotes. We concluded that surgical sterilization of coyotes did not affect territory fidelity, survival rates, or home range maintenance.

Winter space use of coyotes in high-elevation environments: behavioral adaptations to deep-snow landscapes

In the last century, coyotes (Canis latrans) have expanded their range geographically, but have also expanded their use of habitats within currently occupied regions. Because coyotes are not morphologically adapted for travel in deep snow, we studied coyote space use patterns in a deep-snow landscape to examine behavioral adaptations enabling them to use high elevations during winter. We examined the influence of snow depth, snow penetrability, canopy cover, and habitat type, as well as the rates of prey and predator track encounters, on coyote travel distance in high-elevation terrain in northwestern Wyoming, USA. We backtracked 13 radio-collared coyotes for 265.41xa0km during the winters of 2006–2007 and 2007–2008, and compared habitat use and movement patterns of the actual coyotes with 259.11xa0km of random travel paths. Coyotes used specific habitats differently than were available on the landscape. Open woodlands were used for the majority of coyote travel distance, followed by mixed conifer, and closed-stand spruce–fir. Prey track encounters peaked in closed-stand, mature Douglas fir, followed by 50- to 150-year-old lodgepole pine stands, and 0- to 40-year-old regeneration lodgepole pine stands. Snowmobile trails had the most variation between use and availability on the landscape (12.0xa0% use vs. 0.6xa0% available). Coyotes increased use of habitats with dense canopy cover as snow penetration increased and rates of rodent and red squirrel track encounters increased. Additionally, coyotes spent more time in habitats containing more tracks of ungulates. Conversely, use of habitats with less canopy cover decreased as snow depth increased, and coyotes traveled more directly in habitats with less canopy cover and lower snow penetration, suggesting coyotes used these habitats to travel. Coyotes persisted throughout the winter and effectively used resources despite deep snow conditions in a high-elevation environment.

Influence of vegetation structure on the small mammal community in a shortgrass prairie ecosystem

The structure of vegetation, and how this structure varies across a landscape, is crucial to understanding the distribution of wildlife species. Between 2002 and 2004, we sampled small mammal communities and measured vegetation structure at 185 locations across a range of disturbance regimes in a shortgrass prairie ecosystem in southeastern Colorado, USA. At each sampling location, the local disturbance regime was some combination of varying intensity of livestock grazing, military training activity, and fire. Vegetation structural characteristics measured included percent bare ground, basal cover, litter, shrub density, and mean grass and shrub height. Rodent communities were described by richness, diversity, total and per capita biomass, and species abundances. Northern grasshopper mice (Onychomys leucogaster), Ords kangaroo rats (Dipodomys ordii), silky pocket mice (Perognathus flavus), western harvest mice (Reithrodontomys megalotis), white-footed mice (Peromyscus leucopus), southern plains wood rats (Neotoma micropus), thirteen-lined ground squirrels (Spermophilus tridecemlineatus), deer mice (Peromyscus maniculatus), and spotted ground squirrels (Spermophilus spilosoma) accounted for >99xa0% of all captures. Canonical correlation analysis was used to assess the relationship between small mammals and vegetation structure. The first two canonical variates explained over 50xa0% of the variation in vegetation structure and were related to the ratio of bare ground to basal coverage and litter accumulation. Rodent community indices were most strongly related to litter accumulation and shrub density, though the models had low explanatory power. Our results agreed with published findings regarding microhabitat associations and indicated small mammal communities benefited from a system of interacting disturbances and the resulting landscape mosaic.

The influence of road characteristics and species on detection probabilities of carnivore faeces

Abstract Context. Determining reliable estimates of carnivore population size and distributions are paramount for developing informed conservation and management plans. Traditionally, invasive sampling has been employed to monitor carnivores, but non-invasive sampling has the advantage of not needing to capture the animal and is generally less expensive. Faeces sampling is a common non-invasive sampling technique and future use is forecasted to increase due to the low costs and logistical ease of sampling, and more advanced techniques in landscape and conservation genetics. For many species, faeces sampling often occurs on or alongside roads. Despite the commonality of road-based faeces sampling, detectability issues are often not addressed. Aim. We sought to test whether faeces detection probabilities varied by species – coyote (Canis latrans) versus kit fox (Vulpes macrotis) – and to test whether road characteristics influenced faeces detection probabilities. Methods. We placed coyote and kit fox faeces along roads, quantified road characteristics, and then subsequently conducted ‘blind’ road-based faeces detection surveys in Utah during 2012 and 2013. Technicians that surveyed the faeces deposition transects had no knowledge of the locations of the placed faeces. Key results. Faeces detection probabilities for kit foxes and coyotes were 45% and 74%, respectively; larger faeces originated from coyotes and were more readily detected. Misidentification of placed faeces was rare and did not differ by species. The width of survey roads and the composition of a road’s surface influenced detection probabilities. Conclusion. We identified factors that can influence faeces detection probabilities. Not accounting for variable detection probabilities of different species or not accounting for or reducing road-based variables influencing faeces detection probabilities could hamper reliable counts of mammalian faeces, and could potentially reduce precision of population estimates derived from road-based faeces deposition surveys. Implications. We recommend that wildlife researchers acknowledge and account for imperfect faeces detection probabilities during faecal sampling. Steps can be taken during study design to improve detection probabilities, and during the analysis phase to account for variable detection probabilities.

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 2xa0years 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 2xa0years. We observed only one fox outside of the breeding pair attending a den in each of the 2xa0years, 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.

Levels of plasma and fecal glucocorticoid metabolites following an ACTH challenge in male and female coyotes (Canis latrans)

Knowledge of endocrine stress responses can be advantageous for understanding how animals respond to their environment. One tool in wildlife endocrinology is to measure the adrenocortical activity as a parameter of disturbance of animals. Fecal glucocorticoid metabolites (GCMs) provide a noninvasive assessment of adrenocortical activity. Using an adrenocorticotropic hormone (ACTH) challenge administered to 28 captive coyotes (Canis latrans), we measured the levels of plasma cortisol, and fecal cortisol and corticosterone metabolites (i.e., GCMs). Our goal was to determine the dose-response in the plasma and fecal samples following the injection and determine if there were effects of sex, age, and time of day. Specifically, animals were anesthetized for ~u200990xa0min with treatment animals intravenously injected with exogenous ACTH and control animals receiving saline. We collected blood samples prior to injection and at 4 different time points post-injection. We also collected fecal samples 2xa0days pre- and 2xa0days post-injection to measure fecal GCMs and determine if an endocrine stress response could be detected in fecal samples. We found a definite response in cortisol levels in the plasma for coyotes to the ACTH challenge. There was a response in fecal corticosterone 1xa0day post-injection, but the control males showed a similar response indicating a handling effect. Fecal cortisol levels did not indicate a response to the ACTH challenge, and were significantly lower than corticosterone concentrations. We also found significant sex, but not age or diurnal, differences in fecal GCMs. Radioimmunoassays for fecal corticosterone levels appeared to be a reliable indicator of physiological stress in coyotes.

Space use and social ecology of coyotes ( Canis latrans ) in a high-elevation ecosystem: relative stability in a changing environment

Coyote (Canis latrans) spatial and social ecology are variable, but have been little studied in high-elevation environments. In these temperate ecosystems, large ungulates are prevalent and coyote pack size may be large in order for them to scavenge and defend ungulate carcasses from conspecifics in neighboring packs. We initiated a study to understand the spatial and social ecology of coyotes on the Valles Caldera National Preserve, a high-elevation (2450–3400xa0m) protected area in northern New Mexico. Our objectives were to (1) describe the home range size and habitat use of coyotes in the preserve, (2) describe coyote movements within and outside of packs, and (3) to evaluate the relationship between coyote social cohesion and the amount of elk (Cervus elaphus) in the coyote diet. We acquired global positioning system and telemetry locations from 33 coyotes from August 2005 to July 2009. We classified 23 coyotes (70xa0% of individuals) as residents (i.e., territorial) during at least part of the study and ten coyotes (30xa0%) as transients. Overall mean home range size of resident packs was 10.6xa0±xa02.2 (SD) km2. Home range size varied between packs, but did not vary by season or year. Coyotes used dry and wet meadow habitats as expected based on availability; coyotes used riparian habitat more than expected, and forests less than expected. Social cohesion did not vary among biological seasons. Alpha coyotes were more socially cohesive with each other than with other pack members, and a transient exhibited temporal–spatial avoidance of pack members while inside the pack’s territory followed by integration into the pack. Contrary to expectations, we found no relationship between coyote social cohesion and the proportion of elk in coyote diets. We concluded that coyote space use and sociality on the preserve were relatively stable year-round despite changes in biological needs, snow depth, and utilization of variously sized prey.