Study finds capture-based research is safe for polar bears

Two U.S. Geological Survey biologists take samples and measurements of a sedated young male polar bear in Alaska in March 2014. (USGS PHOTO)

A new study suggests that tranquilizing, handling and collaring polar bears does not inflict any negative long-term harm on the animals.

The United States Geological Survey released those findings Dec. 15, which were based on 40 years of research on the southern Beaufort Sea polar bear population.

And the study determined that, following capture, polar bears that had been tagged returned to normal rates of movement and activity within five days and that the presence of collars had no effect on the bear’s physical condition.

“We dug deeply into one of the most comprehensive capture-based data sets for polar bears in the world looking for any signs that our research activities might be negatively affecting polar bears,” said Karyn Rode, lead author of the study and a scientist with the USGS’s polar bear research program.

“Importantly, we found no indication that neck collars, the primary means for obtaining critical information on polar bear movement patterns and habitat use, adversely affected polar bear health or reproduction.”

The study also found that repeated capture, considered three or more times, was not related to effects on health and reproduction.

In their research, biologists evaluated the extent to which current methods of capture may influence activity, body mass, reproduction and survival over a six month period.

Of 2,517 captures between 1987 and 2013, the study found that three polar bears died related to those capture methods.

The study also noted that capture-related polar bear deaths dropped substantially in the late 1980s, when tranquilizing drugs were changed.

While newer, less invasive techniques have been developed to collect hair and biopsy samples, these techniques do not provide complete information on bear health, movements or habitat use, the study found.

So, the USGS says, capture is likely to continue as an important technique for monitoring polar bears.

And the study provides reassurance, says its authors, that this method can be used for research and monitoring with no long-term effects on polar bear populations.

But the study contradicts previous research that contends that capture methods can affect bears for many weeks, and even permanently.

A researcher from Saskatchewan’s Western College of Veterinary Medicine found in 2008 that the capture and handling of bears may affect how they grow and reproduce, particularly in the cases of bears that are captured repeatedly.

Although the study focused on grizzly and black bears, the author said his findings are broadly applicable to other bears.

“We have to look at it as the cumulative effect of a number of stressors, which include drugs, method of capture and handling procedures,” said researcher Marc Cattet. “You add all that stuff together and it equals a significant amount of stress which some animals can cope with and others can’t.”

The USGS findings also counter the position of many Nunavut Inuit, who find the handling of bears to be disruptive to the bears’ movement.

In recent years, those concerns have pushed the Government of Nunavut to introduce less invasive methods of research on the territory’s polar bear population, said Steve Pinksen, the assistant deputy minister of its environment department.

Over the last six years, Pinksen said the GN has invested in aerial surveys in the fall, while polar bears are still travelling along shorelines, to help develop a population estimate.

GN biologists are also using more biopsy darts, he said, which are fired at polar bears from a helicopter. Rather than injecting a tranquillizer into the bear, these darts pull a tiny sample of skin and fat from the bear and then fall of the animal, providing a DNA genetic profile of the animal.

“Those are two things we’ve done as a means of reducing our handling of bears and to still be able to collect data,” Pinksen said.

But, he notes, the GN has no plans to completely eliminate the use of tranquillizer darting.

‘We’re moving away from handling bears, but I would note that we still use the drugs when we need to put on satellite collars,” he said. “It has a lot of advantages… and it’s the only way to delineate population boundaries.”