Alaska Science Center
Effects of capturing and collaring on polar bears: Findings from long-term research on the southern Beaufort population
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Full Publication: http://dx.doi.org/10.1071/WR13225
Product Type: Journal Article
The potential for research methods to affect wildlife is an increasing concern among both scientists and the public. This topic has a particular urgency for polar bears because additional research is needed to monitor and understand population responses to rapid loss of sea ice habitat. Aims. This study used data collected from polar bears sampled in the Alaska portion of the southern Beaufort Sea to investigate the potential for capture to adversely affect behavior and vital rates. We evaluated the extent to which capture, collaring, and handling may influence activity and movement days to weeks post-capture, and body mass, body condition, reproduction, and survival over 6 months or more. Methods. We compared post-capture activity and movement rates, and relationships between prior capture history and body mass, body condition and reproductive success. We also summarized data on capture-related mortality. Key results. Individual-based estimates of activity and movement rates reached near-normal levels within 2-3 days and fully normal levels within 5 days post-capture. Models of activity and movement rates among all bears had poor fit, but suggested potential for prolonged, lower-level rate reductions. Repeated captures was not related to negative effects on body condition, reproduction, or cub growth or survival. Capture related mortality was substantially reduced after 1986, when immobilization drugs were changed, with only 3 mortalities in 2,517 captures from 1987-2013.
Polar bears in the southern Beaufort Sea exhibited the greatest reductions in activity and movement rates 3.5 post-capture. These shorter-term, post-capture effects do not appear to have translated into any long-term effects on body condition, reproduction, or cub survival. Additionally, collaring had no effect on polar bear recovery rates, body condition, reproduction, or cub survival. Implications. This study provides empirical evidence that current capture-based research methods do not have long term implications, and are not contributing to observed changes in body condition, reproduction, or survival in the southern Beaufort Sea. Continued refinement of capture protocols, such as the use of low-impact dart rifles and reversible drug combinations, might improve polar bear response to capture and abate short-term reductions in activity and movement post-capture.