Capture and Handling May Have Long-term Effects on Bears

“We hope this study will increase awareness among researchers and help raise the bar on how we use wild animals in research,” said Marc Cattet, a research associate and adjunct professor with the Western College of Veterinary Medicine.

The retrospective study led by Cattet compiled data from two independent research projects to assess the long-term effects of capture and handling of bears in two geographically distinct areas—grizzly bears in Western Alberta and American black bears in the Pisgah Bear Sanctuary of North Carolina.

“While wildlife researchers have made some great strides in addressing animal welfare concerns by using minimally obtrusive capture and handling techniques, we found that some commonly used procedures still have potential to cause injury, change normal behavior, or more generally affect health in a negative manner,” said Cattet.

The study of a total of 340 black and grizzly bears found that blood analysis results from six of every 10 captured bears showed abnormally high values for muscle enzymes, indicating muscle injury which could be caused by the stress and extreme exertion of bears struggling to escape capture.

Injury was particularly evident in bears captured by leghold snare, a technique widely regarded as an acceptable method of capture for bears and other large carnivores. Enyzmes were also high in one in five grizzly bears darted from helicopter and in one in five grizzly or black bears captured by culvert trap.

The team also found that regardless of the capture method used, bears moved less through their territory after capture, with effects lasting three to six weeks on average after capture.

“This finding warrants more detailed investigation of specific and cumulative effects of other stressors that bears may be exposed to during and after capture, for example, sample collection, marking, and carrying radiotransmitters,” Cattet said.

The team also found that bears captured multiple times tended to lose body fat or gain fat at less than normal rates. “This finding is particularly important because as body condition fades, so too does an animal’s potential for growth, reproduction, and survival,” he said.

Cattet says these findings likely also apply to other wild animals commonly studied through capture and release.

“Not only do researchers have a role to play, but so do government wildlife agencies and funding agencies in supporting research to improve capture procedures and validate alternative techniques to capture,” he said.

Also, government wildlife agencies and groups such as the Canadian Council on Animal Care will need to consider revising guidelines and standard operating procedures followed by animal care committees in granting approvals for field research procedures, he said.

Other members of the research team included B.C. statistician John Boulanger, Foothills Research Institute project manager Gordon Stenhouse, North Carolina State University zoologist Roger Powell, and Powell’s former graduate student Melissa Reynolds-Hogland.

For more information, contact:
Marc Cattet
U of S Professional Research Associate and Adjunct Professor
Western College of Veterinary Medicine
(306) 966-2162