Big bears, little bears, mama grizzlies, baby blackies -- it's summer in Alaska, and the bears seem to be colliding with civilization everywhere.

The U.S. Forest Service issued a warning Friday to hikers on the Iditarod Trail near aptly named Bear Lake, near Seward, to be on the alert for a grizzly sow with cubs that has taken to charging people. A small mob of bears previously led to the closure of the lands adjacent to a popular parking lot and Kenai River ferry crossing near Cooper Landing. Both Cooper Landing and Seward are on the Kenai Peninsula, about 100 miles south of Anchorage, where a local wildlife biologist is taking a public lashing for shooting a couple bears.

Jessy Coltrane, the area wildlife biologist for the Alaska Department of Fish and Game, shot and killed a pair of black bear cubs in a subdivision above the city after their mother was shot and killed by an Anchorage Hillside homeowner.

Coltrane had no real choice. No zoos are interested in taking black bears, and if the small cubs had been left on their own they would have either starved to death, or been killed and eaten by another bear.

Bears in the Hillside area above Anchorage have already killed many bear-cub-size moose calves this year, not to mention at least two and probably more full-grown moose. The latter animals weigh up to 1,000 pounds and are not easy to take down, but the local grizzly bears have done it.

Black bears are one things, grizzlies are another

Alaskans tend to be particularly wary of grizzly bears because of their size and power. It is generally accepted in the 49th state that a healthy adult should be capable of fighting off a black bear, but a grizzly is a different matter. It can injure, or kill, a human with ease. A hunter from Nome on the Seward Peninsula, about 550 miles northwest of Anchorage, stopped to photograph a grizzly earlier this year and within seconds became a victim of its attack. Though friends who were with Wes Perkins when he was mauled shot and killed the bear -- then saved Perkins' life -- he is still recovering.

With one bite, the bear basically tore off the side of Perkins' face. He has spent most of his time since the attack in a Seattle hospital.

The danger posed to people by grizzly bears is why residents in Salcha, a community just south of Fairbanks along the Alaska Highway, are now on edge. Two grizzly sows with five cubs between them are roaming the community looking for food. State wildlife biologists have told local residents to move their barbecues indoors at night and keep their freezers, and even their groceries, out of sight.

In one case, the Fairbanks Daily News-Miner reported, "a sow destroyed a car that had groceries inside, totaling the Mazda by somehow opening a door and demolishing the interior."

This problem is not unique. One Anchorage Hillside homeowner who made the mistake last month of leaving his smoker out, next to his garage door after smoking fish, found himself out on the deck in the wee hours of the morning yelling at a grizzly that really wanted to have a look inside the empty cooking device.

A Hillside veterinarian who keeps horses has for the past several nights been visited by a young grizzly curious as to whether it might just be able to make a meal of one of those animals. The grizzly bears, fortunately, tend to keep to the suburban areas of Anchorage, only sneaking through urban greenbelts with caution -- but not so the black bears.