Ursus arctos sitkensis

Sitka brown bear (US National Park Service)

Accepted scientific name: Ursus arctos sitkensis (Clinton Hart Merriam, 1896); however many authorities recognise only two subspecies of brown bear in North America: the grizzly bear (U.a. horribilis) and the Kodiak bear (U.a. middendorffi).  This places the Sitka brown bear in the subspecies U.a. Horribilis.

In 1918 Clinton Hart Merriam divided the North American brown bears into 86 subspecies based upon small physical differences, mainly relating to skull measurements.  Over time this list has been reduced but some experts believe that there is still sufficient evidence to warrant classifying five North American subspecies in addition to the widely accepted grizzly and Kodiak bear subspecies.  In this website we include those five subspecies; the Sitka brown bear (U.a. sitkensis) being one of them.  However, much of the following information, other than range, is similar or identical to that given on the pages for the Alaskan (U.a.alascensis), Dall (U.a. dalli), Peninsular (U.a. gyas), and Stickeen (U.a. stikeenensis) brown bears.

Description:  A large bear, most commonly dark brown in colour but can range from blonde through to black.  The often grizzled appearance is caused by the light coloured tips of the long guard hairs over the shoulders and back.  The bears have a distinctive hump on the shoulders and a slightly dished profile to the face.  The front claws are noticeably long.  There is considerable variation in size depending upon the food available.  Adult males typically weigh 135 to 390 kg, females 95 to 205 kg.  Adults are usually between 90 and 110 cm at the shoulder.  These bears are usually larger than those of the interior.  Recent reaearch (see “More Information” below) suggests that these bears are the result of inter-breeding between polar and brown bears probably at the end of the last glacial period.

Range:  Found only on Admiralty, Baranof and Chichagof Islands in the Alexander Archipelago, Alaska.

“ABC” Islands of Alaska with the Sitka brown bear’s range outlined in red (US National Park Service / Bear Conservation)

Habitat:  Coastal temperate rainforest typical of southeastern Alaska with  Sitka spruce and western hemlock predominating.  On Baranof Island the  bears occupy the Indian River drainage and occasionally enter the Sitka National Park, often at the beginning of the salmon runs.

Status: Numbers appear to be stable notwithstanding the licensed hunting which takes place.

Life span:  Around 20 to 30 years in the wild.

Food:  Grasses and other plants, bulbs, various berries including salmonberry and blueberry, mushrooms.  Small mammals including voles, mice and squirrels.  Salmon during the runs from mid-July to September.

Behaviour:  The bears reach sexual maturity between the ages of four and seven years.  Mating occurs between May and July.  The bears go into winter dens usually in October or November and emerge in April, May or June.  Cubs are born in the den in January and February, litters usually being of two or three cubs but can be of one or four.  They will remain with the mother for two to three years during which time she will not become pregnant again.  Except for mating and for mothers with cubs, grizzly bears are solitary although they will congregate in groups where there are plentiful sources of food, such as spawning salmon.

Threats:  Hunting and there have been a number of reports of conflicts with humans on Baranof Island.  Poaching including for body parts to be used in medicine seems to be an increasing threat for all bears.  It seems likely that these bears are or will soon be affected by climate change either directly or indirectly as habitat and food sources change or disappear.

MORE INFORMATION

DNA study clarifies relationship between polar bears and brown bears (news article).

For the complete paper on the above please click here.

See below for video clip of a Sitka brown bear fishing.

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Page created 15 August 2017

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