Alaska Wildlife: Brown Bears, Orcas & Moose | Alaska Guide

Alaska contains the highest concentration of large mammal biomass in North America. The state supports an estimated 30,000 grizzly bears, 100,000 black bears, and approximately 175,000 to 200,000 moose according to Alaska Department of Fish and Game population surveys conducted between 2015 and 2023. These figures represent the last remaining stronghold for species that once ranged across the entire western continent. The Kodiak brown bear, a distinct subspecies inhabiting Kodiak Island and adjacent islands, reaches recorded weights exceeding 1,500 pounds in adult males, making it the largest terrestrial carnivore in North America alongside the polar bear. Kodiak Island's approximately 3,500 bears live at the highest density of brown bears anywhere on Earth, supported by abundant salmon runs in streams draining the island's 3,588 square miles.

Grizzly bears in interior and Arctic Alaska follow seasonal migrations tied to caribou calving grounds, berry ripening cycles, and salmon spawning. The Brooks Range supports sparse populations that den at elevations between 2,000 and 4,000 feet, emerging in April when ground squirrel populations become active. Katmai National Park on the Alaska Peninsula documents the continent's most concentrated bear feeding activity at Brooks Falls, where up to 60 individual bears gather during July sockeye salmon runs. Individual bears consume between 80,000 and 90,000 calories daily during peak feeding, gaining three to six pounds per day in preparation for winter dormancy. Female grizzlies enter dens in October weighing 400 to 700 pounds and emerge in April having lost 30 to 40 percent of body mass while nursing cubs born in January.

Alaska's marine ecosystems support distinct orca populations totaling approximately 2,500 individuals in state waters. The resident orca population in Prince William Sound and the Inside Passage consumes exclusively fish, primarily Chinook salmon and halibut, while transient orca populations hunt marine mammals including harbor seals, Steller sea lions, and occasionally gray whales. Genetic analysis distinguishes these groups as reproductively isolated for at least 10,000 years. Resident pods maintain matrilineal social structures where females live 80 to 90 years and males 50 to 60 years. The AT1 transient pod in Prince William Sound numbered 22 individuals before the 1989 Exxon Valdez oil spill and declined to nine animals by 2004, with no calves born since 1984, functionally extinct as a reproducing population. Other resident pods in Southeast Alaska waters show stable numbers with annual calf survival rates near 43 percent based on Center for Whale Research monitoring data.

Humpback whales migrate 3,000 miles from Hawaiian breeding grounds to Alaska feeding waters between April and October. The population feeding in Southeast Alaska, Prince William Sound, and the northern Gulf of Alaska numbers approximately 3,000 individuals, part of a North Pacific population that has recovered from fewer than 1,500 animals in 1966 to over 21,000 by 2008 according to NOAA Fisheries stock assessments. Individual humpbacks consume up to 3,000 pounds of krill, herring, and other small fish daily using bubble-net feeding, a cooperative hunting technique where groups of five to 20 whales blow curtains of bubbles to concentrate prey before lunging upward through the center. Glacier Bay National Park, closed to commercial whaling in 1925, now hosts approximately 100 individual humpbacks each summer, identified through photographic cataloging of unique fluke patterns.

Moose distribution in Alaska extends from the temperate rainforests of Southeast Alaska to the Brooks Range treeline at 68 degrees north latitude. The state's moose population fluctuates between 175,000 and 200,000 animals, representing nearly half of North America's total moose population. Adult bulls in the Alaska Range reach shoulder heights of 6.9 feet and weights exceeding 1,600 pounds, with antler spreads documented up to 6.5 feet. Moose density peaks in the boreal forests surrounding Anchorage, Fairbanks, and along the Kenai Peninsula, where willow and birch browse supports populations of 20 to 30 moose per 100 square kilometers. Winter browse availability determines population dynamics, with deep snow years reducing calf survival to 10 to 20 percent compared to 60 to 80 percent in mild winters.

Caribou migrations across Alaska involve five major herds totaling approximately 750,000 animals. The Western Arctic herd numbers 201,000 animals according to 2019 Alaska Department of Fish and Game census data, down from a peak of 490,000 in 2003. This herd migrates up to 3,000 miles annually between winter range in boreal forests south of the Brooks Range and calving grounds on the Arctic coastal plain. The Porcupine caribou herd, shared with Canada's Yukon Territory, numbers approximately 218,000 animals and calves almost entirely within a 900-square-mile area on the coastal plain of the Arctic National Wildlife Refuge. Timing of migration and calving correlates with snow melt, with the herd arriving at calving grounds within a seven-day window in late May or early June. Calf survival depends on synchrony with peak vegetation greenness, which provides maximum protein for lactating cows.

Dall sheep occupy mountain ranges across Alaska from the Chugach Mountains north to the Brooks Range, with total population estimates between 50,000 and 70,000 animals. Rams develop full-curl horns by age seven to eight years, with some individuals living beyond 16 years in wild populations. Ewes and lambs segregate from rams outside the November to December rutting period, occupying steep terrain where mineral licks provide sodium and other nutrients absent from alpine vegetation. Denali National Park supports approximately 1,700 to 2,000 Dall sheep monitored through annual aerial surveys since 1962, providing the longest continuous population dataset for the species. Winter severity drives population fluctuations, with deep snow limiting access to wind-exposed ridges where frozen vegetation remains accessible.

Gray wolves in Alaska number between 7,000 and 11,000 individuals across the state, exceeding the combined wolf population of the lower 48 states. Pack sizes range from two to 15 animals, with most packs containing five to eight wolves. Territory sizes vary from 200 square miles in areas of high prey density to 1,000 square miles in the Arctic where caribou migrations create seasonal abundance. Wolf predation accounts for 80 percent of adult moose mortality in some interior Alaska populations, while brown bear predation on moose calves in the first weeks of life reaches 50 to 90 percent in areas where bear and moose ranges overlap. The Alaska Board of Game authorizes predator control programs in designated areas where moose populations fall below management objectives for human hunting, reducing wolf numbers through aerial shooting and same-day-airborne hunting permits.

Bald eagles nest in higher densities along Alaska's coast than anywhere else in North America. The Chilkat River drainage near Haines supports the largest documented gathering of bald eagles, with counts exceeding 3,000 individuals in November when late chum salmon runs provide accessible food after other streams freeze. Southeast Alaska contains approximately 30,000 bald eagles, roughly half the North American population. Eagles construct nests in Sitka spruce and cottonwood trees, with some nests used continuously for over 50 years reaching diameters of 10 feet and weights estimated at two tons. Nest site fidelity is high, with pairs returning to the same territory annually, though individual eagles may live 30 years and outlive multiple mates.

Sea otters in Alaska number approximately 70,000 animals, concentrated in the Aleutian Islands, Prince William Sound, and Southeast Alaska. The species was reduced to fewer than 2,000 individuals range-wide by 1911 when international treaty ended commercial hunting. Populations in Prince William Sound and Southeast Alaska recovered to carrying capacity by the 1990s, with densities reaching 30 otters per square kilometer in optimal habitat. Aleutian Islands populations declined 90 percent between 1990 and 2000, attributed to increased killer whale predation after whale populations shifted diet from depleted pinniped populations. Sea otters consume 25 to 30 percent of body weight daily, primarily sea urchins, clams, mussels, and crabs, using rocks as tools to break shells while floating on their backs.

Salmon runs define the ecological calendar across Alaska. Five species spawn in Alaska waters: Chinook, sockeye, coho, pink, and chum salmon. Bristol Bay produces the world's largest sockeye salmon runs, with returns between 30 million and 60 million fish annually supporting commercial harvests that averaged 37 million fish between 2010 and 2020. The Yukon River Chinook salmon run, historically averaging 200,000 to 300,000 fish, declined to fewer than 100,000 fish in most years after 2010, prompting closure of subsistence and commercial fisheries in multiple years. Salmon carcasses transport marine-derived nutrients into freshwater and terrestrial ecosystems, with nitrogen isotope studies showing that streamside vegetation within 200 meters of spawning streams derives 15 to 25 percent of nitrogen from salmon.

Polar bears in Alaska occupy sea ice habitats along the Arctic coast, with two populations sharing territory with Canada and Russia. The southern Beaufort Sea population declined from approximately 1,500 bears in 2001 to 900 bears in 2010, attributed to reduced sea ice extent limiting access to ringed seal prey. Adult males weigh 900 to 1,600 pounds, while adult females weigh 500 to 700 pounds. Pregnant females excavate maternity dens in snow drifts along the coast or on pack ice, giving birth to one to three cubs in December or January. Sea ice extent in the Beaufort and Chukchi seas has declined 14 percent per decade since 1979 based on National Snow and Ice Data Center measurements, reducing the platform polar bears require for hunting seals.