New paper urges wildlife authorities to prepare for worst-case scenarios
Although the world's largest land carnivore is capable of devouring nearly anything it encounters — from whales to lemmings — it cannot survive indefinitely without seals. To hunt seals, polar bears depend on sea-ice. But as climate change keeps the Arctic ice-free for increasingly longer periods, the predators are struggling to find enough prey, and data shows that a single year of prolonged warmth could spell disaster for entire sub-populations of the species. Now, an international team of experts is urging wildlife managers to devise game plans for dealing with the inevitable: a mass polar bear starvation event.
"There is very strong science to suggest that we will soon have a year when the ice-free period extends beyond polar bears' fasting limits," said Oregon Zoo curator Amy Cutting, one of 12 authors of a paper in the journal Conservation Letters that describes a series of polar bear emergency response strategies. "Our goal with this paper is to encourage each government with jurisdiction over polar bears to plan now, because a crisis is a bad time to make critical decisions with long-term repercussions."
The paper outlines a list of measures that may alleviate the worst effects of a crisis, including food airdrops, rehabilitation and translocation further north. Each option is described alongside its limitations and potential long-term consequences.
"Tranquilizing, housing, feeding or airlifting 1,000-pound carnivores in one of the most extreme environments on earth will take tremendous resources and political will," Cutting said. "It is critical that people understand we are not suggesting any of these options will save the species long-term as it currently exists in nature. What we are talking about here is really the Hail Mary pass of polar bear management."
Five nations — the U.S., Canada, Russia, Norway and Greenland — currently manage polar bears, which can be further divided into 19 sub-populations. Many are co-managed between multiple agencies and First Nations groups.
Biologists predict the southernmost populations will be the first ones dramatically affected by climate change. Canada's western Hudson Bay polar bear population is already exposed to longer-than-usual sea-ice thaws, resulting in poorer health, lower survival rates, and escalated conflict with people as the bears seek food.
"No single strategy will be effective for all polar bear populations, and we do not recommend any particular approach," Cutting said. "Wildlife authorities throughout the Arctic will need to adopt individual response plans that are appropriate and acceptable for their communities."
The paper also underscores the critical role zoos may play in determining how to feed, house and treat malnourished bears during a crisis.
At the Oregon Zoo, polar bears Conrad and Tasul are offering researchers unprecedented access to a species that is notoriously difficult to study in the wild. As part of a collaboration with the U.S. Geological Survey, keepers are training Tasul — the zoo's female polar bear — to wear a collar that records and transmits data about her movement. Researchers will videotape her and match the electronic signals with her behavior. Once the signals are calibrated, collars can be placed on free-roaming wild bears, allowing researchers to study how much energy polar bears use.
In another study, Tasul and Conrad will help researchers devise methods for identifying what wild polar bears eat during lean times.
While zoo studies may reveal how polar bears response to climate change, Cutting hopes the Oregon Zoo continues to inspire its visitors to play their parts in creating a better future for the much-beloved white bears.
"The only way we can truly save the species as it exists today is through dramatic and immediate global reduction of greenhouse gas emissions," Cutting said. "This paper should serve as a wake-up call that climate change is already having dramatic impacts on polar bears. If we don't get a handle on climate change, many species, including humans, stand to suffer as well."