Toward a Stress-Free Approach to Capturing and Handling Wild Polar Bears


For the past 90 minutes, X03366 had been in a stable state of anesthesia--his body limp and relaxed, and his vitals normal and steady. At 19 years of age, X03366 was one of the older and larger polar bears camped out along the western Hudson Bay coast awaiting the formation of this year's sea ice, only 4 weeks away.

For the research crew flying south along the coastline in a Bell 206 Jet Ranger helicopter, he was an unmistakable feature on the landscape and an ideal subject in which to test the anesthetic drug combination of medetomidine and ketamine, or MK for short. The pursuit and capture had been brief. The helicopter had swooped quickly into position at about 4 meters above and to the left of the bear's lumbering frame, and a dart that contained a small volume of MK was fired into the large neck muscles of X03366. Six minutes later, the bear was safely anesthetized and lying motionless. And now, after monitoring and recording his physiological function for over an hour, the only procedures that remained were to weigh the bear and then inject a small amount of the reversal drug, atipamezole, into his muscle. Within minutes, the injected atipamezole would "reverse" the effects of MK and allow X03366 to quickly recover from an anesthetized state.

Although weighing an animal in the range of 500 kilograms may seem daunting, determining the weight of X03366 would take only a few minutes with the use of a supportive sling, lightweight aluminum tripod, electronic scale, and hand winch. The tripod was positioned centrally above the bear, the scale connected to the sling, and I began gently pulling down the handle of the hand winch. One ... two ... three pulls and X03366 was almost off the ground. The fourth pull never came. My movement ceased, and my eyes were riveted on the broad head of the bear. Had it been my imagination, or had X03366 just moved? Any doubt was short-lived, however, as I realized I wasn't the only person staring intently at the bear. My co-researcher, Canadian scientist Nigel Caulkett also had his eyes fixed on X03366's head. Further, there was no question the bear's eyes were staring clearly back.

Events over the next few moments unfolded quickly and quietly. X03366 had recovered spontaneously from the anesthetic effects of MK to find himself in a rather awkward and vulnerable position--restrained on his back in a sling suspended a few inches above the ground with people staring down at him. His response was to extract himself from the weighing apparatus and charge toward us. We, in the mean time, had been slowly backing away. The distance between bear and us narrowed quickly, and it appeared inevitable that X03366 would be shot by at least one of our guns pointing at him. As suddenly as the charge began, however, it stopped--the bear simply stared a moment at us, then turned away, walked slowly back toward the collapsed weighing apparatus, and lay down.

This had been terribly close to disaster, and not the way wild polar bears are supposed to be captured and handled. What had gone wrong? In the hours that followed, Caulkett and I reviewed the circumstances surrounding this event, as well as the records of 11 other polar bears that had been anesthetized with MK in the preceding days. There was no doubt in our minds about the conclusion--MK could not be recommended as a safe anesthetic drug for use in polar bears.

Although I work with a variety of the large wild mammals found in Canada, studying polar bears has been a continuous thread and particular passion throughout my 20-year research career. My first exposure to these arctic sea-ice nomads came in 1982 when, fresh out of the University of Guelph with a bachelor's degree in wildlife biology, I ventured north to Yellowknife looking for a career as a government wildlife biologist. Although the anticipated career never came to be, unexpected opportunities to work among polar bears always seemed to arise. They were the species of focus for my M.Sc. research at the University of Alberta in the mid-1980s. Then, after stepping out of wildlife research for a few years in the early 1990s to obtain a veterinary degree and work as a veterinarian with domestic species, the opportunity to work with polar bears availed itself again. This time, they became the species of focus for my Ph.D. research at the University of Saskatchewan. For the past few years I have been fortunate to continue working with polar bears, both as a researcher and wildlife veterinarian based in Saskatoon with the Canadian Cooperative Wildlife Health Centre (CCWHC), a multidisciplinary team of wildlife health experts based at each of Canada's four veterinary colleges. My colleague, Nigel Caulkett, is a professor of veterinary anesthesiology at the University of Saskatchewan and an associate member of CCWHC, who shares a similar passion for learning from polar bears.

Over the past 7 years, Caulkett and I have been directing much of our research with the CCWHC toward determining the physiological responses of large wild mammals to the stressors associated with capture and handling, i.e., drugs, methods of capture, etc. In addition to our work with polar bears, we've also been conducting similar studies with other species, including grizzly bears, black bears, bison, and elk. The results from this research are, in turn, used to make recommendations toward less stressful methods for capturing and handling wildlife. From the perspective of managing wild populations, research is necessary for making management decisions and usually requires some capture and handling of animals. However, the intense stresses associated with capture and handling can cause serious harm, or even death, to the animals we're supposed to be conserving. Further, the effects of capture and handling stress can disturb or influence our understanding of wildlife behavior and ecology.

When wildlife has to be handled, priority should be given to looking after the well being of each animal that is handled. It is not enough to simply manage knocking an animal down and putting a radio collar on it. Considerable effort must go into planning and preparing capture operations and assuring the correct equipment and procedures are employed. You will never take the stress out of capture and handling, but sound decisions based on knowledge, not reaction, will go a long way toward reducing stress.

In the case of polar bears, the attempt to replace the Telazol with MK sounds a little like trying to repair something that wasn't broken. Wild polar bears have been routinely captured in Canada and the U.S. since the late 1960s, and Telazol has been the immobilizing drug-of-choice for at least the past 10 years. It has proven safe, reliable, and effective in polar bears. Was there really need for a different drug? What did this have to do with "reducing the stresses associated with capture and handling?"

Despite the reliability and effectiveness of Telazol in polar bears, the drug also poses some problems. The large volumes (10 ml or more) that must be administered to larger bears can result in substantial injury to the tissues surrounding the injection site. Secondly, the drug has a poor painkilling effect that is insufficient for some of the routine handling techniques applied to polar bears, e.g., tooth extraction for aging. Thirdly, the effects of the drug cannot be adequately antagonized with a reversal drug and only disappear once the drug has been sufficiently metabolized within the animal. As a result, some bears have prolonged recoveries from the drug that take many hours during which time they are potentially vulnerable to predation by other bears, or possibly temperature stresses associated with the local weather. We decided to look at MK because it has been used with good success in a wide variety of wild species and it has been shown to address the problems associated with Telazol.

Currently, major sources of funding for this type of applied research are practically nonexistent. Yet, Caulkett and I have been fortunate to acquire small amounts of money here and there, and often from the wildlife agencies that are managing the species upon which their research is based. Because we also instruct courses in the anesthesia (or chemical immobilization) and handling of wildlife to conservation officers, park wardens, and biologists working with government wildlife agencies, this frequent contact puts us in a particularly good position to develop collaborative research programs with other wildlife professionals. For example, in the case of our work with polar bears, the wildlife branches of Manitoba Conservation and the Churchill Northern Studies Centre has provided consistent support over the years. In fact, with their support, we were able to progress from testing MK in polar bears to testing other combinations of drugs that have so far proven to be more effective with respect to painkilling and reversibility of the effects. Further, the fact that polar bears do not spontaneously recover during anesthesia with the latest drugs has gone a long way toward reducing our own stress levels.

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