'Junk' Food Making Urban Bears Overweight

by Sherry Morse

A study of black bears along the California-Nevada border has found that bears in populated areas have experienced behavioral changes which have made them heavier than bears that do not live near humans.

As part of the study, the movements of fifty-nine bears in the Lake Tahoe basin on the California-Nevada border were tracked using radio collars. Bears who live around humans were found to be less active, spent less time foraging for food and spent fewer days in their winter dens than bears that live in the wild. Some of these 'urban' or 'city' bears did not hibernate at all.

According to study authors John P. Beckmann and Joel Berger of the Wildlife Conservation Society, this is because urban bears live on garbage found at fast food restaurants and in residential neighborhoods.

Beckmann said that for city bears living in residential areas, garbage is the ultimate food resource since it is easily available in the same place week after week and the supply is constantly being replenished.

City bears forage at night, are most likely to avoid people, and sleep during the day - the opposite of normal bear behavior.

The city bears spent just eight hours a day foraging for food and often traveled no more than a mile from their dens. In contrast, the other bears in the study - dubbed 'country bears' by the researchers - spent nearly all their time in the wild and spent more than 13 hours a day foraging for their meals over ranges that extended up to 150 square miles.

A quarter of the city bears were found to weigh over 400 pounds, with some tipping the scales between 500 and 600 pounds. The average country bear weighed between 220 and 300 pounds.

The higher weights found among the city bears parallel the record levels of obesity found among people and domestic pets in the United States who eat the same sort of high-calorie, high-fat diet that the bears have adopted by eating garbage.

The researchers said it is not clear if the city bears' excess weight is causing them to experience health problems.

The study also found that as bears moved into more populated areas, conflicts and bear deaths increased, mostly from encounters with humans which often result from the bears' search for easy sources of food.

This highlights a growing concern in the United States, as human housing development encroaches on farm land and previously unsettled areas of wilderness.

The problem of bear-human conflicts over food "happens over and over and over again," said Ann Bryant, of the Bear League in Lake Tahoe.

"The problem is not the bears; the problem is the people," Bryant said.

Bryant has worked with local communities to pass ordinances preventing the feeding of bears, as well educating people to change their habits in order to better protect the bears.

Beckmann and Berger suggest that one remedy for the problem is for city planners and county commissioners to require businesses and individuals to purchase and use bear-proof dumpsters.

"We know they work," Beckmann said, "Once they go into a homeowners' association, the bears no longer visit."

Mike Mitchell, a bear researcher with the US Geographical Survey, added, "As focused as bears are on food, the less that (they) associate people with food, the better for both bears and people."

© 2003 Animal News Center, Inc.