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The American black bear (Ursus americanus) is highly adaptable and can move long distances in short periods of time. The advent of Global Positioning System (GPS) –equipped telemetry equipment allows researchers to gather data on highly mobile animals with improved temporal and spatial resolution over standard telemetry equipment. We used a GPS-equipped radiocollar to document one of the longest non-dispersing movements of a black bear in New Mexico and Colorado (USA) during July 2011–May 2012, which is atypical because previously documented movements were generally associated with dispersal events. This adult male bear traveled a straight-line distance of 282.2 km (cumulative distance of 1,482.8 km) from the capture site. The bear made this long-distance movement in 304 days. It is unclear how common this type of movement is, but movements of this magnitude can potentially influence genetic diversity, recolonization potential, and have implications for managers in setting harvest regulations.
Intraspecific predation (cannibalism) in brown bears (Ursus arctos) is a behavior rarely documented, and it remains poorly understood. In April 2010 we documented the probable killing and partial consumption of a subadult female bear by a subadult male bear; both bears had been captured during a telemetry study in northern Greece. Intraspecific killing was supported by a match between the inter-canine distance of the male, fatal wounds on the female, and the absence of other bear tracks at the trap site; consumption of the subadult female by the subadult male was witnessed directly by the trapping team. This is the first reported case of probable intraspecific killing and predation of a subadult female by a subadult male brown bear. Though intraspecific predation appears to be a rare phenomenon, trapping teams should always strive to reduce the time an animal is captured in a trap, such as by using trap alarms.
American black bears (Ursus americanus) triggered complaints from property owners across much of Wisconsin, USA, from 2008 to 2010. Wildlife managers provided technical assistance and live-trapped bears to mitigate nuisances. We examined the longevity of these management actions as measured by the risk (or hazard) that a conflict site would generate a subsequent complaint after live-trapping or technical assistance had been implemented. We observed that as one expanded outward in distance from the original complaint site, the number of days separating a management action and a subsequent complaint decreased. Additionally, the number of bears that were translocated from a conflict location was not associated with decreased hazard. The percentages of locations that did not have a subsequent complaint were nearly identical for both technical assistance and live-trapping interventions. Our technique is a practical one, which could be used to analyze existing agency records. Also, our results could improve the benefit–cost calculations of agencies contemplating new or modified nuisance-response protocols for this bear species and perhaps others.
I analyzed 28 fecal samples from Andean bears (Tremarctos ornatus) collected between 2003 and 2007 from the Laquipampa Wildlife Refuge and Yanachaga Chemillén National Park, Peru. I used the direct faeces test and spontaneous sedimentation tube technique to detect cysts, ova, and larvae. To detect intestinal coccidia, I applied acid stain using the Ziehl–Neelsen modified method. I detected parasites in 16 scats (57.1%), identifying 3 protozoa for the first time in the Andean bear: Blastocystis sp., Cryptosporidium sp., and Giardia sp.; as well as 3 nematodes: Strongyloides sp., an undetermined species of Ascarididae, and Ancylostomatidae. The greatest prevalence of parasites were of the family Strongyloididae (25.0%), followed by Ascarididae (21.4%), and Cryptosporidiidae (14.3%). Parasites were found in a greater percentage of scats collected during the dry season (87.5%) compared with the rainy season (16.7%). Overall, 8 species of endoparasites and 1 species of ectoparasite have been identified in Andean bears.
Both black (Ursus americanus) and grizzly bears (U. arctos) are known to rub on trees and other objects, producing a network of repeatedly used and identifiable rub sites. In 2012, we used a resource selection function to evaluate hypothesized relationships between locations of 887 bear rubs in northwestern Montana, USA, and elevation, slope angle, density of open roads and distance from areas of heightened plant-productivity likely containing forage for bears. Slope and density of open roads were negatively correlated with rub presence. No other covariates were supported as explanatory variables. We also hypothesized that bear rubs would be more strongly associated with closed roads and developed trails than with game trails. The frequencies of bear rubs on 30 paired segments of developed tracks and game trails were not different. Our results suggest bear rubs may be associated with bear travel routes, and support their use as “random” sampling devices for non-invasive spatial capture–recapture population monitoring.
American black bear (Ursus americanus) populations have been expanding geographically, in part because bears are learning to exploit agricultural landscapes where crops provide an easy and calorically rich foraging opportunity. Consequently, crop depredation has become a growing problem for farmers and wildlife managers. Bears may raid crops because of insufficient natural foods, a drive to increase body mass, or because they discovered the crop fields while looking for other foods. We tested whether simple food preferences, in the absence of other competing factors present in the wild, influence autumn foraging choices. We conducted food-choice trials with 9 captive black bears in 2010 and 2011 to assess preference among primary autumn food options found in northwestern Minnesota, USA, which is a site of present bear-range expansion. Food choices offered in the trials were acorns (preferred natural food), field corn (Zea mays), and 2 kinds of sunflowers (confection and oil; Helianthus annuus). We measured preferences among the 4 food types, through time, and between sexes. Males immediately preferred oil sunflowers, which provided the highest caloric input. Females exhibited a notable shift from the early trials, where acorns were highly preferred, to later trials where sunflowers were preferred, which was suggestive of learning. We postulate that in the wild, male bears, being more determined to enhance caloric intake, seek out whatever foods best meet this need, thus ranging farther and being less wary of threats or novel tastes. Females initially may be less willing to expand their diet with unfamiliar foods, but our experiments indicate that after some experience, they find anthropogenic foods increasingly appealing.
American black bears (Ursus americanus) occur on numerous islands within the Apostle Islands National Lakeshore in Lake Superior, Wisconsin, USA, and provide an opportunity to better understand patterns in abundance and genetic structure among island populations. In 2002 and 2010, we derived genotypes from DNA obtained from hair samples collected at hair traps to estimate population abundance on Stockton (40.7 km2), Sand (11.9 km2), and Oak (20.6 km2; 2010 only) islands. We used Huggins closed-population mark–recapture models to estimate island-specific abundance and density. We used Program STRUCTURE and parentage analysis to examine inter-island population structure, migration patterns, and relatedness. In 2010, we estimated abundance on Stockton, Sand, and Oak islands to be 13.1 (95% CI = 12.4–13.8), 10.1 (95% CI = 9.3–11.0), and 18.1 (95% CI = 17.3–19.0) bears, with a density of 0.32, 0.85, and 0.88 bears/km2, respectively. Whereas abundance on Sand Island increased 60% since 2002 (N = 6.3, 95% CI = 4.0–8.6), abundance on Stockton declined 50% (N = 26.3, 95% CI = 24.7–27.9), including an 83% decline in detected females. Density on Oak Island was the highest reported in Wisconsin, although we identified 13 individuals as likely mates or offspring of a single male. We identified 4 genetic groups, corresponding to Stockton, Sand, Oak, and Mainland ancestry. No individuals on Stockton or Sand islands were assigned ancestry from another island, whereas one male on Oak Island was assigned Stockton ancestry. We detected individuals of predominately Mainland ancestry on all but Hermit Island, suggesting a high rate of immigration from the mainland. We suggest these islands can support high bear densities, but may undergo rapid shifts in sex-specific abundance. Genetic connectivity appears maintained by male-mediated gene flow, but a small number of wide-ranging females may sustain inter-island population viability.