Foraging ecology of coyotes (Canis latrans): the influence of extrinsic factors and a dominance hierarchy

1996 ◽  
Vol 74 (5) ◽  
pp. 769-783 ◽  
Author(s):  
Eric M. Gese ◽  
Robert L. Ruff ◽  
Robert L. Crabtree

We examined the influence of intrinsic (age, sex, and social status) and extrinsic (snow depth, snowpack hardness, temperature, available ungulate carcass biomass) factors in relation to time–activity budgets of coyotes (Canis latrans) in Yellowstone National Park, Wyoming. We observed 54 coyotes (49 residents from 5 packs, plus 5 transients) for 2507 h from January 1991 to June 1993. Snow depth, ungulate carcass biomass, and habitat type influenced the amount of time coyotes rested, travelled, hunted small mammals, and fed on carcasses. Coyotes decreased travelling and hunting and increased resting and feeding on carcasses as snow depth and available carcass biomass increased. Age and social status of the coyote influenced activity budgets. During times of deep snow and high carcass biomass, pups fed less on carcasses and hunted small mammals more than alpha and beta coyotes. Pups apparently were restricted by older pack members from feeding on a carcass. Thus, pups adopted a different foraging strategy by spending more time hunting small mammals. Coyotes spent most of their time hunting small mammals in mesic meadows and shrub–meadows, where prey densities were highest. Prey-detection rates and prey-capture rates explained 78 and 84%, respectively, of the variation in the amount of time coyotes spent hunting small mammals in each habitat in each winter. Our findings strongly suggested that resource partitioning, as mediated by defense by older coyotes, occurred among coyote pack members in Yellowstone National Park.

1996 ◽  
Vol 74 (5) ◽  
pp. 784-797 ◽  
Author(s):  
Eric M. Gese ◽  
Robert L. Ruff ◽  
Robert L. Crabtree

We examined the intrinsic (age, sex, and social status) and extrinsic factors (snow depth and hardness, temperature, cloud cover, wind speed, and habitat) influencing coyote (Canis latrans) predation of small mammals in Yellowstone National Park, Wyoming. We observed 54 coyotes (49 residents from 5 packs, plus 5 transients) for 2507 h from January 1991 to June 1993. We observed 6433 prey detections by coyotes during which coyotes made 4439 attempts to capture prey, resulting in 1545 successful prey captures. The age of the coyote influenced prey-detection rates, predation attempts, and capture rates, plus the proportions of prey attacked after being detected and capture success. Pups had higher prey-detection rates and higher attempt rates than alphas and betas, but capture rates were similar. Snow depth and hardness and habitat type were factors influencing detection rates, predation attempt rates and capture rates. Coyotes hunted mainly in mesic meadows and shrub–meadows, where prey-detection rates, predation attempt rates, and capture rates were highest. Snow depth influenced coyote predation on small mammals, prey-detection rates, predation attempt rates, and capture rates being highest in low snow cover and lower in deeper snow. Our findings indicated that young, inexperienced coyotes detected and attacked small mammals at a higher rate than older coyotes. Yearlings and adults were more selective, and thus detected and attempted to capture prey at a lower rate than pups. Overall, however, pups and older coyotes captured similar numbers of prey per hour.


2009 ◽  
Vol 123 (3) ◽  
pp. 260 ◽  
Author(s):  
J. W. Sheldon ◽  
Gregory Reed ◽  
A. Cheyenne Burnett ◽  
Kevin Li ◽  
Robert L. Crabtree

We observed a single adult male Coyote (Canis latrans) kill a Bison (Bison bison) calf in Yellowstone National Park. The predation is, to our knowledge, the only direct and complete observation of a lone Coyote capturing and killing a Bison calf. The bison calf had unsuccessfully attempted to ford a river with a group and subsequently become stranded alone in the territory of a six-year-old alpha male Coyote.


2003 ◽  
Vol 81 (6) ◽  
pp. 985-993 ◽  
Author(s):  
T Adam Switalski

Coyotes (Canis latrans) in Yellowstone National Park (YNP) have lived in the absence of wolves (Canis lupus) for over 60 years. I examined whether wolf reintroduction in 1995 and 1996 in YNP influenced coyote vigilance and foraging ecology. From December 1997 to July 2000, my co-workers and I collected 1708 h of coyote activity budgets. Once wolves became established in the Park, they once again provided a continuous source of carrion in the Lamar Valley and we found that coyotes began feeding on carcasses throughout the year. Although we documented that wolves killed coyotes, it also became clear that surviving coyotes quickly adjusted their behaviors when wolves were present. When coyotes were near wolves or in areas of high wolf use, they fed on carcasses much more; however, they increased the amount of time spent in vigilance activities and decreased rest. There appears to be a trade-off in which wolf kills provide a quick source of food that is energetically advantageous to coyotes; however, attendant costs included increased vigilance, decreased rest, and a higher risk of being killed. Changes in the behavior of coyotes in response to the reintroduction of this large carnivore may ultimately have wide-ranging cascading effects throughout the ecosystem.


Author(s):  
Robert Crabtree

Sixty healthy adult coyote Canis latrans and 53, 8-12 week old pups captured at dens were radio­ tagged in the Lamar Valley and Blacktail Plateau areas of the northern range of Yellowstone National Park. Adults range in age from 1 to 12 years and average nearly 3.3 years old. Territorial packs in both study areas are adjacent, non-overlapping, contiguous, and average 15 km2. Based on information from the last four winters and data collected from 1946 to 1949, territorial areas are traditional and have changed little in the last 45 years. We estimate that 85 to 90% of coyotes on the northern range belong to packs. A territorial group or pack during the winter consists of 2 alpha individuals, 2 or 3 beta adults, and 2 or 3 adult-sized pups (average pack size = 7). Fifteen marked coyotes have died since November of 1992. Initial density estimates are 1.4 coyotes per square mile. Preliminary scat analysis suggests that small mammals, especially voles, dominate the diet with ungulate remains becoming important in May through July (presumably elk calves) and late winter (mostly scavenging). Two graduate students have finished their data collection and another student is currently working on his last field season. More than 2500 hours of foraging observations were conducted from January 1991 through June 1993 resulting in data collection on more than 4400 predation attempts on small mammals. Eight hundred and fifty hours of den observations were completed during 1992 and 1993. Beta pack members were observed to bring food to pups and protect den sites from intruders. Coyote behavior and ungulate mortality data were collected on sixty-one carcasses found during the 1992-1993 winter. Five successful and 4 unsuccessful predations by coyotes on ungulates have been seen. Coyotes appear to impact ungulate numbers in 3 ways: predation on calves and fawns shortly after birth (up to 8 weeks), predation on short-yearlings and adults during winter, and indirect impact from harassment of other predators at ungulate-kills. Coyotes may be the major ungulate predator on the northern range due to their cooperative social and foraging behavior, ability to take advantage of vulnerable ungulates, and high population levels. Wolf extirpation has probably resulted in high coyote population densities and coyotes have, at least partially, slid into this vacant niche.


1997 ◽  
Vol 33 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Eric M. Gese ◽  
Ronald D. Schultz ◽  
Mark R. Johnson ◽  
Elizabeth S. Williams ◽  
Robert L. Crabtree ◽  
...  

Author(s):  
R. Moore ◽  
M. Wood

As part of the National Park Service's goal of maintaining an area in as natural condition as possible, Yellowstone National Park in 1972 developed a fire policy whereby natural fires were allowed to burn in wilderness areas of the park. Several investigators have studied the relationship between small mammals and fire due to timber management practices (Gashwiler, 1970 and Tevis, 1956) but few studies have investigated the changes in abundance and composition of species of small mammals after recent natural fires (Bendell 1974). The purpose of this ongoing study is to quantify the effects that recent natural fires have had upon small mammal communities. Two burn sites were studies, the Divide fire which burned in 1976 on the south arm of Yellowstone Lake, and the Trail Creek Fire which burned in 1974 on the southeast arm of the lake.


Author(s):  
Robert Crabtree

Fifty-four healthy coyotes (Canis latrans) and 32, 8-12 week old pups captured at dens were radio­tagged in the Lamar Valley and Blacktail Plateau areas of the northern range of Yellowstone National Park. Seven of the 40 captured in the fall were 6 month-old pups which suggest slow population productivity. Adults range in age from 1 to 12 years and averaged nearly 4 years old. Territorial packs in both study areas are adjacent, non-overlapping, contiguous, and averaged 15 km2/ We estimate that 85 to 90% of coyotes on the northern range belong to packs. A territorial group or pack during the winter consists of 2 alpha individuals, 2 or 3 beta adults, and 2 or 3 adult-sized pups (average pack size = 7). Nine adults were killed (2 mountain lion [Felis concolar], 2 road-kill, 2 shot, and 3 unknown) which equates to a 15% annual mortality rate. Eleven of 36 pups have died between the ages of 3 and 9 months old. Population productivity ranges from 2.0 to 2. 7 pups recruited per territory. The reproductive failure rate among breeding groups averaged 15% during 1990 and 1991. Initial coyote density estimates are 0.09 per km2. Intensive foraging observations were conducted from January through June 1991. In 353 hours of focal observations 427 capture attempts were made on small mammal prey with 162 (38%) successful. Habitat type played a key role in the success rate. Mesic meadows had the highest capture rates followed by willow/meadow habitats and sage habitat. Small mammals, especially voles (Microtus spp.), dominate the diet with ungulate remains becoming important in May through July, presumably elk (Cervus elaphus) calves and late winter, mostly scavenging. We have observed numerous successful and unsuccessful predation attempts on ungulates in our study areas. Coyotes appear to impact ungulate numbers in 3 ways: predation on calves and fawns shortly after birth (up to 8 weeks), predation on short-yearlings and adults during winter, and indirect impact from harassment of other predators at ungulate-kills. Coyotes may be the major ungulate predator on the northern range due to cooperative social and foraging behavior, their ability to take advantage of vulnerable ungulates, and their high population levels. Wolf (Canis lupus) extirpation has probably resulted in high coyote population densities.


2018 ◽  
Vol 96 (9) ◽  
pp. 1032-1042 ◽  
Author(s):  
H.W. Martin ◽  
L.D. Mech ◽  
J. Fieberg ◽  
M.C. Metz ◽  
D.R. MacNulty ◽  
...  

Despite encounter rates being a key component of kill rate, few studies of large carnivore predation have quantified encounter rates with prey, the factors that influence them, and the relationship between encounter rate and kill rate. The study’s primary motivation was to determine the relationship between prey density and encounter rate in understanding the mechanism behind the functional response. Elk (Cervus elaphus Linnaeus, 1758) population decline and variable weather in northern Yellowstone National Park provided an opportunity to examine how these factors influenced wolf (Canis lupus Linnaeus, 1758) encounter rates with elk. We explored how factors associated with wolf kill rate and encounter rate in other systems (season, elk density, elk group density, average elk group size, snow depth, wolf pack size, and territory size) influenced wolf–elk encounter rate in Yellowstone National Park. Elk density was the only factor significantly correlated with wolf–elk encounter rate, and we found a nonlinear density-dependent relationship that may be a mechanism for a functional response in this system. Encounter rate was correlated with number of elk killed during early winter but not late winter. Weak effects of snow depth and elk group size on encounter rate suggest that these factors influence kill rate via hunting success because kill rate is the product of hunting success and encounter rate.


Author(s):  
Robert Crabtree

Sixty-five healthy coyote (Canis latrans) adults and 53, 8-12 week old pups captured at dens were radio-tagged in the Lamar Valley and Blacktail Plateau areas of the northern range of Yellowstone National Park. Adults range in age from 1 to 11 years and averaged nearly 3 years old. Territorial packs in both study areas are adjacent, non­overlapping, contiguous, and averaged 15 km2. Based on information the last three winters and data collected from 1946 to 1949, territorial areas are traditional and have changed little in the last 45 years. We estimate that 85 to 90% of coyotes on the northern range belong to packs. A territorial group or pack during the winter consists of 2 alpha individuals, 2 or 3 beta adults, and 2 or 3 adult-sized pups (average pack size = 7). Only one radioed adult coyote has died since May of 1992. Twenty­ four of 53 pups have died between the ages of 3 and 9 months old. Population productivity ranges from 1.8 to 2.5 pups recruited per territory. The reproductive failure rate among breeding groups averaged 15% during 1990 and 1991. Initial density estimates are 1.4 coyotes per square mile. Intensive foraging observations were conducted from January through June 1991 (353 hours) and from November 1991 through April 1992 (1100+hours). Focal observations collected from January-June 1991 resulted in 427 capture attempts on small mammal prey with 162 (38%) successful. Habitat type played a key role in the success rate. Preliminary analysis of the November 1991 to April1992 data indicated a substantial reduction in prey attempts and prey success. This reduction was mostly a function of harsh snow conditions in early winter and abundlint elk carrion in late winter. Over eighty ungulate carcass were located this winter in the 2 study areas. However, small mammals, especially voles, dominate the diet with ungulate remains becoming important in May through July (presumably elk calves) and late winter (mostly scavenging). We have documented numerous successful and unsuccessful predation attempts on ungulates in our study areas. Coyotes appear to impact ungulate numbers in 3 ways: predation on calves and fawns shortly after birth (up to 8 weeks), predation on short-yearlings and adults during winter, and indirect impact from harassment of other predators at ungulate-kills. Coyotes may be the major ungulate predator on the northern range due to cooperative social and foraging behavior, their ability to take advantage of vulnerable ungulates, and their high population levels. Wolf extirpation has probably resulted in high coyote population densities and coyotes have, at least, partially slid into this vacant niche.


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