Harvest-based demographic estimation of a brown bear population on the Oshima Peninsula, Hokkaido
We constructed a population dynamic model using demographic parameters with uncertainties by using long-term harvest data and estimated population dynamics of brown bears (Ursus arctos) on the Oshima Peninsula, Hokkaido, Japan, from 1968 to 2021 with population trend indicators obtained by forest sign survey and an upper population limit calculated by extrapolating an estimated density […]
Documentation of an Asiatic black bear preying on a living sika deer caught in a leg-hold snare trap
Asiatic black bears (Ursus thibetanus) rarely prey on living adult deer. We report video documentation, obtained May 2024, of a bear subduing and killing a sika deer (Cervus nippon) that was captured in a leg-hold snare trap, then staying in the area for repeated feeding visits. Leg-hold snare traps for deer capture are widely used […]
Grizzly bear behavior in south-central Alaska: Use of a hidden Markov model to assess behavior
Attempts to understand wildlife population dynamics and implement management practices benefit from understanding animal behavior traits. In Alaska, USA, grizzly bear (Ursus arctos) behavior is important to understand because the species is an apex predator, exerts top-down population effects, and is a cornerstone species across complex landscapes. Our objectives were to examine how environmental and […]
Factors affecting body weight fluctuation in free-ranging Asian black bears
The Asian black bear (Ursus thibetanus) shows seasonal changes in body weight, activity level, and range use. However, there is little information available on these factors in individuals in the wild. We documented the body weights of free-ranging Asian black bears from spring to autumn, 2017 to 2019, in the Nikko-Ashio Mountains, Tochigi Prefecture, Japan, […]
Possible sexually selected infanticide by polar bears in western Hudson Bay
Infanticide occurs in a diversity of taxa and may provide benefits to the perpetrator through nutritional gain, reduced competition, or increased fitness from mating opportunities through sexually selected infanticide (SSI). Infanticide, however, is rarely observed. We documented a probable infanticide event by a 23-year-old adult male polar bear (Ursus maritimus) on a 3-month-old cub in […]
Denning ecology of an at-risk American black bear population in a unique habitat on the Bruce Peninsula, Ontario, Canada
The American black bear (Ursus americanus) population on the Bruce Peninsula in southern Ontario, Canada, is small (∼300 bears), genetically isolated from the closest bears in other parts of Ontario because of geography and urban development, and it is at risk because of habitat loss. The Bruce Peninsula is underlain by dolostone, and soils over […]
Andean bears below the Andes
We lack many quantitative data on the current distributions of several bear species, and hypotheses about the mechanisms underlying those distributions. We raise this point by discussing visual detections of Andean bears (Tremarctos ornatus) in sampling from 14 September 2016 to 24 August 2017 in the Haramba Queros Wachiperi Ecological Reserve Conservation Concession in southeastern […]
Sea ice dynamics influence movement patterns of adult female polar bears in southern Hudson Bay
To access seals (Pinnipedia), polar bears (Ursus maritimus) move large distances over the sea ice in winter. Already documented declines in ice duration for Hudson Bay, Canada, are predicted to continue, likely affecting polar bear movement patterns. Using data from global positioning system (GPS) collars, 2007-2011, we describe movement patterns of adult female polar bears […]
Grizzly bear and American black bear interactions with people in Yellowstone National Park
In North America, polar bears (Ursus maritimus), grizzly bears (U. arctos), and American black bears (U. americanus) occasionally injure or kill humans. Although bear-inflicted human injuries are uncommon, they generate media attention that can lead to fear and unreasonable perceptions of the risk of bear attacks. Information on the behavioral responses of grizzly and black […]
A case of hyperdontia in grizzly bear in British Columbia
Hyperdontia refers to an excess number of teeth past the expected number of teeth for an individual located in the mandible or maxilla. These extra teeth are often referred to as ‘supernumerary.’ This condition is a relatively uncommon, infrequent phenomenon scarcely documented in Ursidae globally, with only a handful of examples documented in literature. In […]