Review and Evaluation of Breakaway Devices for Bear Radiocollars
Researchers often handle radiocollared bears on an annual basis, so collars can be readjusted. However, if a collar cannot be refitted (as when a bear becomes lost to the investigator because of radio transmitter failure), the animal may be subjected to lifelong neck irritation or more serious injury. To prevent this, devices have been developed […]
A Method for Dating Tetracycline Biomarkers in Black Bear Cementum
Dating of the tetracycline biomarker in a tooth section of a black bear (Ursus americanus) can be accomplished by noting its position relative to that of the cementum annuli which indicate age. However, annuli and biomarkers are best demonstrated by different laboratory techniques. The technique used for the biomarker, calcified sections examined using epi-fluorescence microscopy, […]
Evaluation of Age Determination of Polar Bears by Counts of Cementum Growth Layer Groups
The ages of polar bears (Ursus maritimus) of known age from 2 to 18 years were estimated through counts of cementum growth layer groups in 105 vestigial, first premolar teeth. Each tooth was read independently by both investigators. The reader with more experience achieved an accuracy of 75% and estimated 93% of the teeth to […]
Calculating Average Age of First Reproduction Free of the Biases Prevalent in Bear Studies
The average age of first reproduction appears to be a useful index of habitat quality for bear populations. However, the conventional method for calculating this age, using only bears whose first litters were observed, gives a low-biased estimate. This bias is a consequence of losing bears approaching their cub-producing years due to death, lost radio […]
Aerial Sightability and Classification of Grizzly Bears at Moth Aggregation Sites in the Absaroka Mountains, Wyoming
In 1991-92, we simultaneously observed grizzly bears (Ursus arctos horribilis) from the ground and air at moth aggregation sites east of Yellowstone National Park, Wyoming, to determine the ability of aerial observers to sight and classify bears. The Interagency Grizzly Bear Study Team (IGBST) uses aerial surveys to count and monitor the reproductive success of […]
Methodology for Maintaining Observer Independence in Aerial Strip Transect Surveys
We describe the internal communication systems and data recording protocol used for aerial strip transect surveys of polar bears (Ursus maritimus) conducted in the Beaufort Sea in June 1994. The communication system permitted 4 observers and a pilot to independently communicate bear sightings to a data recorder. This method allowed us to estimate the proportion […]
Identifying and Mitigating Errors in Satellite Telemetry of Polar Bears
Satellite radiotelemetry is a useful method of tracking movements of animals that travel long distances or inhabit remote areas. However, the logistical constraints that encourage the use of satellite telemetry also inhibit efforts to assess accuracy of the resulting data. To investigate effectiveness of methods that might be used to improve the reliability of these […]
Testing Assumptions in Bear Research: Using Statistical Power Analysis to Estimate Effects of Den Type on Black Bear Cub Survival
Statistical tests on data from black bear (Ursus americanus) research often have low power because of limited sample sizes and sometimes subtle effects. We used the assumption that den type (open nest, hollow tree, excavation, etc.) has some effect on first year cub survival to illustrate the use of statistical power in black bear research. […]
Bear-Human Conflict Management in Denali National Park and Preserve, 1982-94
In response to a dramatic increase in visitation and in problems with grizzly and black bears (Ursus arctos, U. americanus) during the 1970s, Denali National Park and Preserve implemented a comprehensive bear-human conflict management plan in 1982. The components of Denali’s bear-human conflict management plan include visitor education, food-storage regulations, backcountry closures, and experimental aversive […]
Fishing Bridge: 25 Years of Controversy regarding Grizzly Bear Management in Yellowstone National Park
Scientists and managers want to use the best available information to make decisions that affect natural resources. However, we believe the case history of research and management of the grizzly bear (Ursus arctos) in the Fishing Bridge area of Yellowstone National Park typifies the frequent failure of effective information transfer between scientists, managers, and the […]