Brown bears have come to symbolize the Alaskan wilderness more than any other animal. Ninety-five percent of the United State's population live in Alaska, and Lake Clark supports a healthy and stable population.
Brown and grizzly are common names for the same species; the difference between the two is geographic location, which influences diet, size, and behavior. Those that live in coastal areas are called brown bears, while typically inland bears that have limited or no access to marine-derived food resources are called grizzlies. Both have the distinctive large shoulder hump, long curved claws, and a wide head with a concave profile, often described as "dish-faced." In Lake Clark, both coastal brown bears and inland bears are of the subspecies Ursus arctos horribilis. In Lake Clark we refer to them all as brown bears.
Lark Clark's Coastal Brown Bears
Viewing a gathering of several of America's largest land predators is an awe-inspiring experience indeed, yet one that is a daily occurrence along Lake Clark's Cook Inlet coast during the summer months. This area includes unique habitat that provides an abundance of food sources for brown bears. Protein-rich sedges and other edible plants grow in sprawling salt marshes that lie in close proximity to salmon-filled streams and tidal flats rich in clams. Whales and other marine carcasses occasionally wash ashore. Berries can be found on the nearby hillsides.
Brown bears intent on foraging on these rich food sources will congregate in close proximity with one-another. Park biologists conducting aerial surveys have counted as many as 219 brown bears within a 54 square mile area on the coast in recent years. This is among the highest densities in the world.
This high concentration of bears in a small area is possible because with more than enough food, they are more tolerant of the presence of each-other than they are where food is scarce. In order to avoid most conflict, these naturally solitary animals establish a fluid hierarchy when gathered together. Through the use of vocalizations, scent, and body posturing weaker, less dominant bears yield space, breeding rights, and optimum feeding locations to stronger, more dominant individuals. Learning how they communicate is one way you can avoid conflict with bears and remain safe in bear country, too.
The energy-rich diet of Lake Clark's coastal brown bears allows the largest males to reach weights exceeding 1,000 pounds by the time they enter the den to hibernate. Most adult males typically weigh 600-900 pounds by mid-summer, while females average 1/3 less in weight. This is carried on a frame 3-5 feet tall at the shoulder and 7-10 feet in length.
Lake Clark's Inland Brown Bears
Referring to the eating habits of a grizzly, John Muir once commented, "to him almost everything is food except granite." While not far off the mark for any member of the Ursus arctos family, it is especially true of the bears who do not have the benefit of the coast's abundant food sources.
The habitats in the inland portions of Lake Clark west of the Aleutian Mountain Range differ considerably from those on the coast. Gone are the salt marshes filled with protein-rich sedges that nourish the coastal browns through mid summer. Gone are the tidal flats that abound in a reliable source of clams year-round. In their place are boreal forests and open tundra crisscrossed with salmon-bearing rivers and lakes.
Because their food source is scarcer and more scattered, brown bears living in the interior of Lake Clark are typically not as large as their coastal brethren. They rely more heavily on berries, roots, insects, and ground squirrels. While an inland grizzly will never encounter a beached whale to feast upon, it is more likely to scavenge a caribou carcass or bring down a moose calf; though this is not a steady source of food, but rather an occasional treat.
However, due to the seasonal abundance of salmon that spawn in many of the park and preserve's inland waterways, most of the bears here do get larger than those in areas that lack the high protein salmon provide. Depending on the lake or river, salmon can be a reliable food source June - October.
Because competition for resources is higher inland, brown bears here revert to their solitary nature and do not gather in high numbers. They will interact with fewer individuals in their lifetime than a coastal bear, and are less tolerant of the presence of those they do encounter. They are also more likely to react to people from a greater distance.
Did You Know?
Salmon migrate to the Lake Clark area from as far away as the western end of the Aleutian chain. During their homeward journey, they average 35 miles per day.