Effects of elk group size on predation by wolves

2002 ◽  
Vol 80 (5) ◽  
pp. 800-809 ◽  
Author(s):  
Mark Hebblewhite ◽  
Daniel H Pletscher
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Cervus Elaphus ◽  
Canis Lupus ◽  
National Park ◽  
Risk Model ◽  
Wolf Predation ◽  
Banff National Park ◽  
Density Relationship ◽  
Large Groups

Wolf-prey research has focused on single-prey systems in North America dominated by moose (Alces alces) or white-tailed deer (Odocoileus virginianus). Elk (Cervus elaphus) are social ungulates and the main prey item of wolves (Canis lupus) in Banff National Park (BNP), Alberta. Grouping behaviour may affect the functional response of predators by changing how predators encounter and kill prey. We studied wolf predation on elk in BNP during the winters of 1997–1998 and 1998–1999 and tested how elk group size affected the availability of and encounter rates with elk groups and attack success of wolves. Wolves encountered larger elk groups than expected based on availability, and killed more elk from large groups than expected based on numbers of encounters. Elk group size increased with elk density in BNP. Increased rates of encounter with and success of attacking large elk groups, and the positive group size – density relationship may be a mechanism for density-dependent predation. We developed a predation-risk model to test the prediction that grouping will benefit individual elk, given this predation regime. Elk appeared to adopt two different strategies to minimize predation risk: living in small herds that were rarely encountered by wolves or living in large herds that reduced their predation risk through dilution.

Context dependence of elk (Cervus elaphus) vigilance and wolf (Canis lupus) predation risk

2014 ◽  
Vol 92 (8) ◽  
pp. 727-736 ◽  
Author(s):  
Cristina Eisenberg ◽  
David E. Hibbs ◽  
William J. Ripple ◽  
Hal Salwasser
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Cervus Elaphus ◽  
Canis Lupus ◽  
National Park ◽  
Forest Edge ◽  
The North ◽  
Edge Group ◽  
North Fork ◽  
Complex Picture

To assess the relationship between predation risk perceived by elk (Cervus elaphus L., 1758) as evidenced by vigilance, we conducted focal animal observations in elk winter range. We stratified our observations in Glacier National Park, Montana, USA, and Waterton Lakes National Park, Alberta, Canada, in valleys with three wolf (Canis lupus L., 1758) population levels (Saint Mary Valley: no wolf; Waterton Valley: moderate wolf; North Fork Valley: high wolf). Although the lowest elk vigilance occurred in Saint Mary and the highest in the North Fork, our analysis revealed a complex picture. Our model included distance to forest edge, group size, distance to road, social class, and impediments to detecting and escaping wolves. In Saint Mary, none of the variables were significant. In Waterton, vigilance decreased as elk group size increased (p < 0.00001) and increased as impediments increased (p = 0.0005). In the North Fork, vigilance increased as group size increased (p = 0.03), bulls were more vigilant (p = 0.02), and the interaction between group size and impediments was significant (p = 0.03). Where a high wolf population existed, elk did not exhibit uniform or expected response to predation risk factors. High wolf presence may necessitate adaptive elk behaviour that differs from response to moderate wolf presence.

Elk population dynamics in areas with and without predation by recolonizing wolves in Banff National Park, Alberta

2002 ◽  
Vol 80 (5) ◽  
pp. 789-799 ◽  
Author(s):  
Mark Hebblewhite ◽  
Daniel H Pletscher ◽  
Paul C Paquet
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Cervus Elaphus ◽  
Snow Depth ◽  
National Park ◽  
Linear Models ◽  
Information Criteria ◽  
Factors Affecting ◽  
Wolf Predation ◽  
Banff National Park

Gray wolves (Canis lupus) recolonized the Bow Valley of Banff National Park in the mid-1980s after a 30-year absence. Wolves recolonized one zone of the Bow Valley in 1985 and another in 1991, but human activity excluded wolves from a third zone throughout the study. Elk (Cervus elaphus) are the primary prey of wolves in Banff National Park. We studied the effects of wolf predation, snow depth, elk density, and human-caused mortality on the elk population growth rate in the three different wolf recolonization treatments from 1985 to 2000. We constructed a set of generalized linear models of factors affecting population growth, and used Akaike Information Criteria to guide model selection and inference. In the low wolf predation zone, elk population growth was density-dependent and limited by human-caused mortality. In the zone that wolves recolonized in 1991, elk population growth was limited by the combined effects of snow depth and wolf predation after wolf recolonization, in addition to preexisting mortality caused by humans and other predators. Our correlative approach failed to yield insights into population dynamics in the zone where wolves were present throughout the study. However, by comparing zones we demonstrate important differences in ungulate population dynamics in the presence and absence of wolf predation.

scholarly journals Trophic Cascades and Historic Aspen Recruitment in the Gallatin Elk Winter Range of Southwest Montana

2005 ◽  
Vol 29 ◽  
pp. 89-95
Author(s):  
Joshua Halofsky ◽  
William Ripple
Keyword(s):  
Populus Tremuloides ◽  
Cervus Elaphus ◽  
Canis Lupus ◽  
National Park ◽  
Fire Suppression ◽  
Gray Wolf ◽  
Climate Trends ◽  
Wolf Predation ◽  
Winter Range ◽  
Conifer Invasion

The extirpation of the gray wolf (Canis lupus) by 1930 in Yellowstone National Park (YNP) provided us with an opportunity to study historic aspen (Populus tremuloides ) recruitment with and without a top carnivore predator present. Herbivory, climate trends, fire records, and current conifer invasion were also examined within the context of aspen recruitment. We obtained tree cores and diameter at breast height measurements to create an aspen age-diameter relationship which we used to approximate aspen origination dates. One elk (Cervus elaphus) exclosure, erected in 1945 within the same elk winter range, was compared to the rest of the winter range. Consistent recruitment inside the exclosure began in the 1940s and has continued into the present. Outside of the exclosure, aspen recruitment began decreasing in the 1930s and ceased in the 1950s. Within the scope of the study, we found little correlative evidence between aspen decline and climate trends, conifer invasion, or fire suppression. The results are suggestive of a trophic cascade between aspen recruitment, and historical elk browsing activities as affected by the absence or presence of wolf predation.

Wolf predation risk associated with white-tailed deer movements

1991 ◽  
Vol 69 (10) ◽  
pp. 2696-2699 ◽  
Author(s):  
Michael E. Nelson ◽  
L. David Mech
Keyword(s):  
Predation Risk ◽  
Odocoileus Virginianus ◽  
Canis Lupus ◽  
Climatic Conditions ◽  
Male And Female ◽  
Wolf Predation ◽  
Adult Females ◽  
Disproportionate Number ◽  
Short Time ◽  
Antipredator Strategy

The survival of 159 yearling and adult deer (Odocoileus virginianus) was monitored by telemetry during 282 spring and 219 fall individual migrations to winter deeryards in northeastern Minnesota. A disproportionate number of deer were killed by wolves (Canis lupus) during fall migration relative to the short time they spent migrating, but not during spring migration. Predation was also significantly greater for male and female yearlings and adult females outside deeryards during winter. Survival of 79 yearlings dispersing from natal ranges was high (1.00). It appears that changing climatic conditions combined with unfamiliar terrain and undetermined factors predispose migratory deer to wolf predation during fall. These findings support an earlier hypothesis that winter yarding is an antipredator strategy.

Does habitat type modify group size in roe deer and red deer under predation risk by Iberian wolves?

2008 ◽  
Vol 86 (3) ◽  
pp. 170-176 ◽  
Author(s):  
I. Barja ◽  
S. Rosellini
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Roe Deer ◽  
Habitat Type ◽  
Capreolus Capreolus ◽  
Antipredator Response ◽  
The Mean ◽  
Grouping Behavior

We examined whether group size in red deer ( Cervus elaphus L., 1758) and roe deer ( Capreolus capreolus (L., 1758)) under predation risk by Iberian wolves ( Canis lupus L., 1758) is affected by the type of habitat in which the deer reside. We hypothesized that group size (i) would be larger in open than in closed habitats, since it is an antipredator response, and (ii) would vary more with habitat type in the species that had higher wolf predation rates. In the study area, wolves were the only predator of wild ungulates, with roe deer being the main target prey. We performed monthly transects along paths to observe the group size of red and roe deer. In roe deer, the mean group size was significantly higher in open than in closed habitats, serving as an antipredator response. However, in red deer, habitat type did not affect group size. The results indicate that under predation risk by wolves the habitat type influences the grouping behavior of roe deer but not red deer. Furthermore, compared with forests, heaths offer less protection from predators and species in this habitat would benefit from larger group sizes.

Threat of predation: do ungulates behave aggressively towards different members of a coyote pack?

1999 ◽  
Vol 77 (3) ◽  
pp. 499-503 ◽  
Author(s):  
Eric M Gese
Keyword(s):  
Body Size ◽  
Aggressive Behavior ◽  
Cervus Elaphus ◽  
Yellowstone National Park ◽  
National Park ◽  
Bison Bison ◽  
Antilocapra Americana ◽  
Wild Canids ◽  
Pronghorn Antelope ◽  
Large Groups

Wild ungulates have evolved a variety of antipredator strategies to deter or escape predation by carnivores. Among wild canids, the dominant pair of a pack often initiates attacks upon prey. Previous observations in Yellowstone National Park, Wyoming, showed that the alpha pair in a coyote (Canis latrans) pack most often leads attacks on ungulates during winter. We were interested in determining whether ungulates can distinguish (perhaps by body size or posture) which members of a coyote pack are the alpha individuals, and whether they initiate and direct aggressive behavior towards those members of the pack that pose the greatest threat of predation to themselves and (or) their offspring. During 2507 h of behavioral observations on 54 coyotes between January 1991 and June 1993, we observed 51 interactions between coyotes and adult elk (Cervus elaphus), bison (Bison bison), and pronghorn antelope (Antilocapra americana) in Yellowstone National Park. The interactions analyzed here are those in which the ungulate appeared to initiate aggressive behavior towards the coyote(s) and were not a response to an attack by the predators. We found that aggression by ungulates towards coyotes was highest during the summer months, when calves and fawns were present; female ungulates were more frequently aggressive than males. The frequency of aggression of adult ungulates towards small and large groups of coyotes was equal to the frequency of occurrence of these groups. Ungulates directed aggressive behavior more frequently towards alpha coyotes and were less aggressive towards beta coyotes and pups. Large ungulates, particularly elk and bison, appeared to perceive that alpha coyotes posed a greater threat to themselves and their offspring. The smaller ungulate, the pronghorn antelope, directed aggressive behavior equally towards all coyotes. Adult ungulates were probably responding to the larger body size of the alpha coyotes and the tendency of alpha coyotes to travel at the front of the pack.

scholarly journals Wolf, Canis lupus, Avoidance Behaviour of American Elk, Cervus elaphus, in Jasper National Park, Alberta

2009 ◽  
Vol 123 (3) ◽  
pp. 236 ◽  
Author(s):  
Dick Dekker ◽  
Greg Slatter
Keyword(s):  
Cervus Elaphus ◽  
Canis Lupus ◽  
National Park ◽  
Radio Signal ◽  
Athabasca River ◽  
Jasper National Park ◽  
Winter Range ◽  
Wooded Area ◽  
Human Habitation ◽  
Local Herd

An American Elk calf (Cervus elaphus) that was captured near human habitation in Jasper National Park, Alberta, was fitted with a radio-collar and released 40 km away in the park's main valley of the Athabasca River. The calf joined a local herd of elk, and its radio signal revealed that the elk, in two months' time, travelled eight times back and forth between the herd's traditional semi-open winter range at Devona and a largely wooded area at Rocky River >3 km away. Each time, on their trans-valley route the elk crossed a busy highway, a railway, and a partly frozen river. Sightings of elk and Wolves (Canis lupus) were inversely correlated on 97 days of observation at Devona. We conclude that the elk's migrations were prompted by their urge to avoid and flee from Wolves, which were common at both locations.

scholarly journals Unusual Behavior by Bison, Bison bison, Toward Elk, Cervus elaphus, and Wolves, Canis lupus

2004 ◽  
Vol 118 (1) ◽  
pp. 115 ◽  
Author(s):  
L. David Mech ◽  
Rick T. McIntyre ◽  
Douglas W. Smith
Keyword(s):  
Cervus Elaphus ◽  
Canis Lupus ◽  
Yellowstone National Park ◽  
National Park ◽  
Bison Bison ◽  
Unusual Behavior

Incidents are described of Bison (Bison bison) in Yellowstone National Park mauling and possibly killing a young Elk (Cervus elaphus) calf, chasing wolves (Canis lupus) off Elk they had just killed or were killing, and keeping the wolves away for extended periods. During one of the latter cases, the Bison knocked a wolf-wounded Elk down. Bison were also seen approaching wolves that were resting and sleeping, rousting them, following them to new resting places and repeating this behavior. These behaviors might represent some type of generalized hyper-defensiveness that functions as an anti-predator strategy.

Sign in / Sign up

Export Citation Format

Share Document