SWIMMING GRIZZLY BEARS ARE ‘ COLONIZING’ B.C. ISLANDS.
BEAR POPULATION SHIFT PUTS ECOSYSTEM AT RISK
When a 450-kilogram hungry grizzly shows up unannounced on a sleepy B.C. island, it has a way of bringing things to a standstill.
“Do not seek out or attempt to interact with the bears. Pick all fruit that might be growing on trees in your yard,” read a warning posted at key locations throughout Alert Bay, a village of 1,500 on Cormorant Island, a 400-hectare islet near the northern tip of Vancouver Island.
Two bears, a brother and sister, had “island hopped” from the mainland. A direct swim would be about 50 kilometres, but the pair had broken up the trip with regular pit stops along the chain of islands that dots the Queen Charlotte Strait.
Villagers, who had been getting reports of their approach since mid-September, went into lockdown: rounding up pets, cancelling students’ recess, roping off recreational trails and sealing the garbage dump.
“I never thought I would see the day,” wrote one resident alongside a Facebook image of the two bears lumbering past a driveway.
The invasions are only set to continue. Increasingly, biologists have noticed that B.C. grizzlies are taking to the sea in search of new areas to conquer.
“They are far bigger and more dominant than black bears, and can easily bully their way into the best fishing spots and habitats once they arrive,” said Christina Service, a University of Victoria bear researcher, in an email to the National Post from Klemtu, B.C., where she is conducting fieldwork.
Service was head of a detailed survey of grizzly movements along B. C.’s central coast. Her team drew on indigenous knowledge, remote camera images, hair-sample analysis and hunting data. All the information pointed to the same conclusion: Grizzly bears were showing up on islands that, as far as anyone could remember, had never seen them before.
Ten islands now hosted grizzlies living outside their known range, the researchers found. Most surprisingly, some of the colonists were female. They weren’t just wandering lone males; they were bringing their families.
“The ecological, cultural, and economic consequences of this distribution shift in coastal grizzly populations might be considerable,” read the team’s 2014 paper.
An adult grizzly fears almost nothing, eats almost everything and can take in 40 kg of food a day. For fragile island ecosystems — and for the smaller black bears which already live on B.C.'s coastal islands — the arrival of such a creature is a miniature natural disaster.
Grizzlies will intimidate or kill the native black bears, which may prompt a black bear exodus. Service’s team even suggested grizzlies might force out the iconic spirit bear, a rare species of white- furred black bear native to B.C.’s central coast.
It’s not clear why this is happening. Salmon runs are at record lows, giving bears more incentive to travel in search of food. Coastal development may be pushing them out of traditional stomping grounds. In addition, the province has curbed trophy hunting of the bears, which could mean there are more of the animals competing for scarce mainland resources.
“Animals … undertake longer excursions for dispersal when populations are increasing and territorial pressures rise,” said Service.
Grizzly bears roam almost every square kilometre of the B.C. mainland, save for the built- up areas around Metro Vancouver and the arid southern interior. Nevertheless, Haida Gwaii, Vancouver Island and the hundreds of islands in between have remained grizzly- free for centuries.
The bears are powerful swimmers. The grizzly’s close cousin, the polar bear, spends so much time in the water that some biologists even consider it a marine mammal. The grizzly, meanwhile, can chug along for extended distances at a speed of five knots — roughly the top speed of a standard rowboat.
While the bears would still have difficulty crossing the wide strait between Vancouver and Victoria or the Gulf Islands, farther north their journey is helped by a stretch of water so packed with islands getting across it is merely a series of short swims.
“On one of the newly colonized islands in the Great Bear Rainforest, bears need only to swim a mere 250 metres to reach island habitat,” said Service.
This wouldn’t be the only unorthodox activity by central coast grizzlies. Service says they have also been seen eating sea urchins, “a feeding strategy we have not previously observed in nearby mainland populations.”
The bear expansion is likely to continue, but there are barriers. The mountains in central Vancouver Island would deter bears accustomed to flatter terrain, while in populated areas, they risk being shot.
Telegraph Cove, near Alert Bay, saw an island- hopping grizzly break into a fish hatchery in 2013, killing a guard dog. Conservation officers trapped and destroyed the animal, surmising it was too acclimatized to human food sources, and would probably return if relocated.
In populated areas, “people tend to panic and the poor bears do not last very long before they are killed," Chris Darimont, science director for the Raincoast Conservation Federation, told the Cowichan Valley Citizen.
But for Alert Bay, at least, the bear invasion is over.
Conservation offi cers tracked every move of the siblings during their six days on the island. Ultimately, they were done in by their love of Cormorant Island plums.
A concoction of plums, beaver and bacon lured the bears into traps Thursday morning, where they were tranquilized and readied for shipment back to grizzly bear country.