Black bears with a taste for fast food grow fat and lazy on easy pickings

Obesity caused by fast-food diets, a growing scourge of American society, is now even affecting wild bears, researchers in the United States have found.

Black bears living near American towns and cities are changing their feeding habits, devoting more and more time to raiding rubbish bins and tips, and in conseqeuence growing overweight from the left-overs of fast-food meals, said the Wildlife Conservation Society (WCS) in New York.

High-calorie, high-fat diets have led to record levels of obesity among people and even domestic pets in the US. Now a study organised in Nevada has found that black bears living near urban areas are picking up the worst eating habits of their human neighbours.

Bears that wander into populated areas to scavenge for food were also found to be less active than those in the wilderness, said Dr Jon Beckmann and Dr Joel Berger of the WCS.

They said many black bears no longer bothered hunting for food in their wild habitats. Instead, the constant supply of high-calorie fast food found in rubbish bins was an easier way for the animals to get year-round sustenance.

The researchers used radio collars to track the movement of 59 bears in the Lake Tahoe basin on the California-Nevada border. They found that the animals fell into two distinct groups.

One group, the "country bears", spent nearly all their time in the wild. The second group, the "city bears", virtually lived in urban areas and feasted on the rubbish and left-over food of local people.

A bear fattening up for winter needs a massive 20,000 calories a day.

And while country bears spent more than 13 hours a day looking for food, their lazier cousins in the city spent slightly more than eight hours feasting on human left-overs.

In winter, country bears spent more time in their dens, avoiding the cold and lack of food outside. But city bears took advantage of the year-round supply of left-overs and kept on eating, the study found.

The end result was that the city-dwelling animals were fatter than the average bear.

A quarter weighed more than 400lb, compared with an average of 220lb to 300lb. Some weighed between 500lb and 600lb.

Whether the bears' health suffered because of their greater weight was not clear. But as more bears wander into, or live in, urban areas, the more likely they are to come into contact with humans.

Many are hit by cars and killed, and the dangers of a city mean more bears are dying than being born in some areas, the study says.