Mortality rate high for Nevada’s urban bears
November 30, 2006
Mortality rates increase substantially for the bears living in urban areas where garbage provides a steady and rich diet, just one of the many differences between urban bears and those living in the wild, according Carl Lackey, wildlife biologist with the Nevada Department of Agriculture.
“From spring emergence to date, there have been 32 bear mortalities at Lake Tahoe and along the Carson front this year, all caused by humans,” he said.
Twenty-two were hit by cars, and the balance were killed for either eating domestic livestock or entering buildings.
Between 200 and 300 bears inhabit the area and as the bears die, others are drawn into the urban interface, where they are exposed to hazards they wouldn’t face in the wild.
Wild bears tend to have two cubs, urban bears three. But that statistic is balanced by the fact that two out of three urban cubs are killed by cars in their first year, Lackey said.
Due to the rich and abundant food source, urban bears tend to be 30 percent heavier and their population is more concentrated. The population of black bears has not increased, but population densities near urban areas have.
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Urban bears inhabit smaller territories, between three and four square miles, compared to their wild counterparts, with territories of 25 to 75 square miles. Hibernation for urban bears can be several weeks shorter, if they hibernate at all.
The future is bleak for the animals, due primarily to development and the garbage that’s left unprotected, Lackey said.
“There’s nothing wrong with living out there, but people shouldn’t leave trash exposed, plant fruit trees, or have a koi pond,” he said.
Along with Dr. Jon Beckmann, of the Wildlife Conservation Society, Lackey has studied bears and their migration into urban areas since 1999.
Known as black bears, their historic range extended throughout Nevada, but has been reduced to the Pine Nut Mountains, remote areas of the Carson Range and in the Wassuks Range near Hawthorne.
Their numbers shrank dramatically about 100 years ago, and viable populations have been reduced to rare sightings, Lackey said.
In the wild, black bears eat mostly grasses, berries, pine nuts and other vegetation. They are primarily loners, but tolerate other bears if a rich source of food is available.
It’s been a good year for fruit production, and several bears in the Genoa area are enjoying that, Lackey said.
“The bears aren’t stupid,” he said. “If they’re eating the fruit, they’re also tipping the trash, and there isn’t much I can or will do. People need to take exclusionary measures.”
If the garbage and other factors were properly secured or removed from the Tahoe Basin and east side of Carson Valley, the bears would return to the wild. There would still be a few sightings, but nuisance problems would be all but eliminated, Lackey said.
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