Forest, Wildlife, and Climate News

Inbreeding takes toll on Mich wolves

By JOHN FLESHER, Chicago Tribune, April 2, 2009 [here]

The gray wolves of Isle Royale National Park are suffering from backbone malformations caused by genetic inbreeding, posing yet another challenge to their prospects for long-term survival, wildlife biologists said Thursday.

Although confirmed only recently, the problem apparently has been festering for decades in the small, isolated packs that wander the island chain in northwestern Lake Superior. The abnormalities, also found in some domestic dogs, can cause pain and partial paralysis while limiting the range of motion so crucial for predators in the wild.

The discovery raises the ethically thorny question of whether scientists should try to dilute the gene pool by introducing wolves from elsewhere, said researchers with Michigan Tech University in Houghton, which hosts a 51-year-old study of the island park’s wolves and moose. …

Although part of Michigan, Isle Royale is closer to Minnesota and Ontario. Moose found their way to the island — probably by swimming the 15 miles from Canada — around 1900. Two or three wolves arrived in the late 1940s, crossing a rare ice bridge from the mainland.

Weather, food availability, disease and other factors have caused the two species’ populations to fluctuate over the years. The most dangerous period for the wolves came in the 1980s, when their total dropped to 12 because of a parvovirus outbreak.

Their population stood at 24 this winter, roughly the long-term average. They were divided into four packs. …

Spinal malformation from inbreeding poses no immediate threat of extinction, Peterson said. The biggest short-term problem is a drop-off in moose, the wolves’ primary food supply, which scientists attribute to climate change. This winter’s moose census turned up 530 — only about half their long-term average and a drop-off from last year’s estimated 650.

The study team is considering whether to propose a “genetic rescue” — trapping unrelated mainland wolves and bringing them to Isle Royale, hoping they would breed and mix their genes with the existing population.

The question involves competing scientific and ethical values, Vucetich said.

Opponents of intervention believe humans should not tinker with wilderness systems. Even if Isle Royale’s wolves die out, their loss would provide information that could save endangered species elsewhere.

Other would counter that attempting to save the wolves also could yield valuable data, while sparing individual animals from painful bone deformities. … [more]