Wolf (Canis lupus) impacts on prey are a central post‐wolf‐reintroduction issue in the greater Yellowstone ecosystem (GYE) of the western United States. Further, estimates of wolf kill rates, used to understand these impacts, can be biased due to unrecovered kills. In Yellowstone National Park (YNP), visibility of wolves allowed us to combine independent aerial and ground observations and use a double‐count method to estimate the probability of recovering kills. We consequently used these data to adjust estimates of wolf kill rates. We conducted monitoring annually from 1995 to 2000 during 2 30‐day periods in early (15 Nov–14 Dec) and late winter (Mar). Estimated recovery rates of wolf kills for ground and aerial crews were 50% and 45%, respectively, although we determined that this varied by location (distance from road) and possibly age (calf or adult) of the kill. The estimated combined recovery rate was 73%. Estimated wolf kill rates were higher in late winter (2.2 kills/wolf/month) compared to early winter (1.6 kills/wolf/month), with an overall estimated rate of 1.9 kills/wolf/month. The primary prey of wolves in winter was elk (Cervus elaphus; 90%). During our study, 43% of the elk killed were calves, 28% were adult females (cows), 21% were adult males (bulls), and 9% were of unknown age/sex. Comparing prey selection to prey availability, wolf packs residing on the northern range (NR) of the GYE selected for calves, against cows, and approximately proportional to availability for bulls. Prey use was different for wolf packs occupying the NR compared to packs residing in other areas (non‐northern range [NNR]) and varied seasonally for NR packs. Variation in wolf kill rates by season, and the relative stability of the northern Yellowstone elk herd during a series of mild winters despite increases in wolf density, suggest that kill rates and ultimately elk population size are influenced by winter weather. Management of ungulates should reflect the addition of wolves combined with the unpredictability of winter weather in the mountainous terrain of the western United States.

We analyzed the leadership behavior of breeding and nonbreeding gray wolves (Canis lupus) in three packs during winter in 1997–1999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking (N = 158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts (N = 591) and 71% of observed travel time (N = 64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors (N = 104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.

Gray wolves (Canis lupus) in upper Michigan, USA, have been monitored since 1991 when breeding activity in mainland Michigan was documented for the first time since 1954. Based on winter track counts, the mean annual rate of increase in abundance was 19% from 1995 to 2002, with the population reaching an estimated 278 animals in 2002. Our objectives were to (1) increase the efficiency of wolf management in Michigan by evaluating alternative and less extensive sampling approaches for population estimation, and (2) evaluate habitat for wolves based on occupancy after a decade of recovery. For the first analysis, we created 22 discrete sampling units that cover upper Michigan, and we evaluated abundance estimates based on various sampling plans using known distribution and populations from the 2000-2002 winter track surveys. We evaluated each plan based on the precision, bias, and confidence interval coverage. A random sampling plan with regression estimator returned the most precise estimates, but a stratified sampling plan, using low, medium, and high wolf density strata had the greatest precision at lowest effort. For the habitat evaluation, we compared white-tailed (Odocoileus virginianus) deer density and road density between wolf pack locations from 1995 to 2001 to random locations outside of the current wolf range. We estimated white-tailed deer density by a spatial interpolation of pellet group counts. Our resource selection function indicated that probability of wolf occupation of an area was positively correlated with deer density, and it was relatively constant for road densities <0.4 km/km 2 but declined sharply at higher road densities. For areas habitable by wolves in upper Michigan, we predict a road density threshold of 0.7 km/km 2 and a deer density threshold of approximately 2.3-5.8 deer/km 2 . We believe that these results will aid managers who need to estimate wolf abundance and predict wolf distribution. JOURNAL OF WILDLIFE MANAGEMENT 69(4):1660-1669; 2005

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse induced bone loss in bears into novel treatments for osteoporosis.

Disuse typically uncouples bone formation from resorption, leading to bone loss which compromises bone mechanical properties and increases the risk of bone fracture. Previous studies suggest that bears can prevent bone loss during long periods of disuse (hibernation), but small sample sizes have limited the conclusions that can be drawn regarding the effects of hibernation on bone structure and strength in bears. Here we quantified the effects of hibernation on structural, mineral, and mechanical properties of black bear (Ursus americanus) cortical bone by studying femurs from large groups of male and female bears (with wide age ranges) killed during pre-hibernation (fall) and posthibernation (spring) periods. Bone properties that are affected by body mass (e.g. bone geometrical properties) tended to be larger in male compared to female bears. There were no differences (p > 0.226) in bone structure, mineral content, or mechanical properties between fall and spring bears. Bone geometrical properties differed by less than 5% and bone mechanical properties differed by less than 10% between fall and spring bears. Porosity (fall: 5.5 ± 2.2%, spring: 4.8 ± 1.6%) and ash fraction (fall: 0.694 ± 0.011, spring: 0.696 ± 0.010) also showed no change (p > 0.304) between seasons. Statistical power was high (>72%) for these analyses. Furthermore, bone geometrical properties and ash fraction (a measure of mineral content) increased with age and porosity decreased with age. These results support the idea that bears possess a biological mechanism to prevent disuse and age-related osteoporoses.