Kodiak & Its Bears
©Mara Weisenberger
The Kodiak Archipelago sits in the North Pacific Ocean along the western portion of the Gulf of Alaska. It is punctuated by deep fjords and characterized by richly diverse habitats extend from the shoreline to alpine within a few kilometers. The archipelago is home to millions of salmon, a plethora of bird species, and the great Kodiak bear.
Cubs are born in the den during January or February.
Weighing less than a pound at birth with little hair and closed eyes, they suckle for several months, emerging from the den in May or June, weighing 15-20 pounds.
Typical litter sizes are 2-3 cubs. Sows are sometimes seen with 5 or 6 cubs in tow, probably due to adopting cubs from other litters.
Most cubs stay with their mothers for 3 years. Over 25% of the cubs die before they leave, with cannibalism by adult males being one of the major causes of death.
Bears that have recently left their mothers, at ages 3-5, have a high mortality rate as they face the world on their own. These “juvenile delinquents” of bear society are also the ones most likely to cause problems with people.
Kodiak bears become sexually mature at age 5 and can continue to produce cubs throughout their lives. The average interval between litters is about 4 years.
Mating season is during May and June. They are serially monogamous (having one partner at a time), staying together for a couple days or a couple weeks. As soon as the egg is fertilized and divides a few times, it enters a state of suspended animation until autumn when it finally implants on the uterine wall and begins to grow again.
Kodiak bears begin entering their dens in late October. Pregnant sows are the first to go to dens, males are the last. Males begin emerging from their dens in early April, while sows with new cubs may stay in dens until late June. Some males may forego denning, staying awake all winter.
Click on a card to check the answer on the back.
c) 34
The oldest known wild Kodiak bear was a 34-year-old sow. The oldest boar was 27.
b) winter
Cubs are born in the den during January or February.
b) False.
While they are the world's largest bears, Kodiak Bears are actually omnivores!
b) 2-3
Typical litters have 2-3 cubs. Sows are sometimes seen with 5 or 6 cubs in tow, probably due to adopting cubs from other litters.
The Kodiak Archipelago is in the western portion of the Gulf of Alaska, stretching from the Barren Islands in the north to the Semidi Islands and Chirikof Island in the south. Kodiak, the largest and most complex island in the Kodiak Archipelago, is located in the western Gulf of Alaska (56o 45’–58o 00’ N by 152o 09’–154o 47’ W), 408 km south of Anchorage, Alaska. It is up to 160 km long, varies from 15 to 130 km in width and has a landmass of 8,975 km2 (3,465 mi²). Afognak (1,813 km²; 700 mi²), Sitkalidak (300 km2; 120 mi²), Sitkinak (236 km2; 91 mi²), and Shuyak (168 km²; 65 mi²) are the next largest islands in the archipelago, with numerous other mid-sized and small islands, reefs, and rocks making up the remainder of the island group. No point of the archipelago is farther than 21 km (13 mi) from the sea as deep fjords slice into the islands. Shelikof Strait separates the archipelago from the mainland on the west, with a 40–65 km (25 – 40 mi) swath of extreme ocean currents and windswept waves.
The Archipelago is geologically an extension of the Kenai Mountains and is part of an uplift zone between 2 major tectonic plates. There are numerous faults and seismic activity is common. Complementing the seismic movements is the relentless erosion of shorelines by the sea and the mountaintops by wind, rain, and glaciers.
Its most prominent feature is the central spine that runs the length of the island from northeast to southwest. The spine is made up of intrusive rock formations sculpted by prehistoric and active glaciers. The tallest peak along the spine rises to 1,362 m. Most of the valleys on the island contain the remnants of scouring by glaciers that covered most of the islands about 12 thousand years ago. The only portion of the archipelago that escaped that glaciation is in the southwest part of Kodiak. This “refugium” is unlike any other part of the island, with wet tundra expanses bordered by modest mountain ridges. On the border of the refugium is a series of large lakes that fill glacially carved valleys. The largest of these, Karluk Lake, is 21 km (13 mi) long, 4 km (2.5 mi) wide, and up to 126 m (413 ft) deep. The Karluk drainage is also the longest river system on the island at 68 km (42 mi).
© Matt Van Daele
© Masumi Palhof
© Masumi Palhof
The Kodiak Archipelago has a sub-arctic maritime climate. Low-pressure systems, spawned along the Aleutian Chain, spin counterclockwise into the Archipelago with easterly winds that bring cool moist weather throughout the year. These systems are periodically disrupted by high-pressure systems that develop over mainland Alaska. The resultant winds from those systems are from the northwest and they typically bring drier weather with more extreme temperatures. Whenever especially strong systems collide, the resultant storms can bring hurricane force winds with heavy rains. Fog is common on the rare days when winds are calm.
Historical weather data from the archipelago is only available from Kodiak city, located near sea level on the northeastern tip of Kodiak Island. From 1991–2020, averageFebruary temperatures (the coldest month) ranged from –3.3 to 1.7oC (26– 35oF) and average August temperatures (the warmest month) ranged from 10.0 to 16.7oC (50 – 62oF). The highest temperature ever recorded from1913 – 2023, was 30.0 oC (86oF) and the lowest was –26.7oC (-16oF). Average annual precipitation was 198 cm (78 in). Winds were common throughout the year with an average annual wind speed of 4.9 mps (11 mph); velocities over 22.4 mps (50 mph) have been recorded in every month. Most of the eastern side ofKodiak Island had weather patterns similar to those recorded at Kodiak city. The south and west sides of KodiakIsland had a drier climate with similar temperatures and higher maximum wind speeds. Because of the diverse nature of the landscape on Kodiak Island, the weather varies greatly from one area to the next.
The sea surrounding Kodiak Island remains ice-free throughout the year. Narrow bays with substantial freshwater influence and protection from most storms can become frozen for several months during winter. Nearshore ocean temperatures typically vary from 0.5oC (33oF) in January to 13oC (55oF) in August. The daily tides on the east side of the archipelago average 2.4 m (7.9 ft) while those on the west side average 4.9 m (16.1 ft), with 2 sets of tides being the daily norm. The maximum daily variation on the east side is 4.2 m (13.8 ft) and on the west side the maximum is 7.2 m (23.6 ft). This dramatic tidal difference between each side of the archipelago results in substantial tide rips between the larger islands.
Kodiak Island is located 970 km (603 mi) south of the Arctic Circle. The sun is relatively low on the horizon throughout most of the year, and produces long twilight hours. During winter months there is a minimum of 6 hours and 29 minutes of daylight, while during the summer solstice, the sun is above the horizon for 18 hours and 9 minutes.
© Matt Van Daele
© Mara Weisenberger
© Masumi Palhof
© Larry Van Daele
Sitka spruce (Picea sitchensis) are common on the northeastern end of Kodiak Island, the eastern half of Afognak and all of Shuyak Islands. Spruce is a relatively new inhabitant to the archipelago, expanding southward from the Kenai Peninsula within the last 800 years. Devil’s club (Echinopanax horridum), high-bush blueberry (Vaccinium ovalifolium), and bracken fern (Dryopteris dilatata) were the principle understory vegetation in forested areas. Since the late 1970s, aggressive timber harvest activities on Afognak Island have altered much of the eastern half of the island from original spruce forest habitat to second-growth spruce and mixed-grass shrub habitat.
A diversity of habitats occurs throughout the remainder of the archipelago, with shrub-grass-forb complexes predominant throughout lowland (<150 m; < 493 ft) and mid-slope (150-500 m; 493 – 1640 ft) areas. Representative species are Sitka alder (Alnus crispa sinuata), Kenai birch (Betula kenaica), salmonberry (Rubus spectabilis), red-topped grass (Calamagrostis canadensis), European red elder (Sambucus racemosa), willows (Salix spp.), fireweed (Epilobium angustifolium), and cow parsnip (Heracleum lanatum). Cottonwood (Populus balsamifera), and willow communities are common along stream bottoms. On southeastern Kodiak Island and all of the islands south of Kodiak, extensive areas of regularly-spaced hummocks (0.3 –1.0 m; 1.0 – 3.3 ft tall) and moist tundra are common.
Alpine vegetation (>500 m; 1,640 ft elevation) includes various mixtures of low willow, ericaceous shrubs (heath), sedge (Carex macrocheata), crowberry (Empetrum nigrum), low-bush cranberry (Oxycoccus microcarpus), alpine blueberry (Vaccinium uliginosum), red bearberry (Arctostaphylos rubra), and a wide variety of forbs.
Nearshore waters supported locally abundant crops of marine vegetation, including bull kelp (Nereocystis luetkeana), eelgrass (Zostera marina), and bladderwrack (Fucus gardneri). Tidal action and storms often deposit parts of these plants on the beach to supplement shoreline vegetation such as goose tongue (Plantago maritima), beach pea (Lathyrus maritimus), beach greens (Honckenya peploides), and beach rye (Elymus arenarius).
Sitka Spruce Forest © Masumi Palhof
Salmonberry © Masumi Palhof
Lingonberries © Masumi Palhof
Beach Greens © Masumi Palhof
Only 6 land mammals were considered indigenous to the Kodiak archipelago. These original inhabitants were brown bear, red fox (Vulpes vulpes), river otter (Lontra canadensis), short-tailed weasel (Mustela erminea), little brown bat (Myotis lucifugus), and tundra vole (Microtus oeconomus). Confirmation of original inhabitants was, however, impossible due to the geologic history of the islands. The constant uplifting and erosion of the terrain is not conducive for development of a useable fossil record.
Sitka black-tailed deer (Odocoileus hemionus sitkensis) were introduced from southeastern Alaska in the late 1800s. By the 1960s deer had dispersed throughout the Archipelago. Winter mortality was the most significant limiting factor for the deer population, with estimated population sizes ranging from <50,000 to >100,000 from 1982-2023. Roosevelt elk (Cervuselaphus roosevelti) were translocated from the Olympic Peninsula in Washington state to Afognak Island in 1929 and currently occupy all of Afognak and Raspberry Islands. Both deer and elk are an important hunting resource for the residents of and visitors to the Kodiak islands and an opportunistic food source for bears.
Mountain goats (Oreamnos americanus) were translocated to northern Kodiak Island from the Kenai Peninsula in 1952 and 1953. The first hunting season was authorized in 1968, as the population expanded in number and range. In 2002, the estimated goat population was 1,400 and they occupied all suitable habitats on Kodiak Island.
Other successful translocations to Kodiak included Arctic ground squirrels (Citellus undulatus) (prehistoric), reindeer (Rangifer tarandus) (1924); muskrat (Ondata zibethica) (1925); beaver (Castor canadensis) (1925); and snowshoe hares (Lepus americanus) (1934).
Read more about game transplants in Alaska from Alaska Department of Fish & Game.
Red Fox ©Matt Van Daele
Sitka Black-tailed Deer ©Masumi Palhof
Beaver
Kodiak’s diverse habitats provide wintering, resting, and breeding areas for 237 different bird species. There are an estimated 1.5 million seabirds that winter near Kodiak, and 350,000 that nest within the 140 seabird colonies that have been identified along the islands.
About 150,000 to 200,000 waterfowl—including geese, sea ducks, and puddle ducks—winter in the area with some staying to breed.
There are also at least 40 species of shorebirds that come to Kodiak either as a migration stop or as a breeding area.
Terrestrial birds include about 70 species of passerines and upland game birds.
There are 18 species of raptors reported on Kodiak, the most common being the bald eagle (Haliaeetus leucocephalus). Up to 3,000 bald eagles spend the winter on the islands, with a breeding population of up to 1,000 eagles.
Savannah Sparrow © Masumi Palhof
Bald Eagle © Masumi Palhof
Kodiak’s lakes and streams provid critical spawning and rearing habitat for 5 species of Pacific salmon (Oncorhynchus spp.), steelhead (O. mykiss), arctic char (Salvelinus alpinus) and Dolly Varden (S. malma). The first salmon to return to most streams on the archipelago each year are the sockeye (red) salmon (O. nerka). Each year about 6 million sockeye return. Another species that returns to Kodiak in late May is the chinook (king) salmon (O. tschawytscha). These are the largest of the salmonids, but they also have the most restricted distribution on the archipelago, occurring in large numbers in only the Ayakulik and Karluk drainages. Average annual returns are about 40 thousand chinook salmon.
In mid-summer chum (dog) salmon (O. keta) return to spawn in Kodiak streams. Each year about 800 thousand chums come back to Kodiak. Another mid-summer returnee and the most abundant salmonid in both distribution and number is the pink (humpback) salmon (O. gorbuscha). The strength of the return of pinks varies between 5 million in odd years and 11 million in even years. The last salmon to come back to Kodiak each year are the coho (silver) salmon (O. kisutch), arriving in late summer and averaging an annual return of approximately 400 thousand fish.
In 2021, the estimated resident human population of Kodiak Island was 12,787, and has been slowly decreasing over the previous 20 years. Well over 90% of the populace lives on northeastern Kodiak Island, with the other residents dispersed in 6 outlying villages. Roads are restricted to the northeast coast of the island, and the immediate vicinity of villages. Kodiak’s inland habitat is contiguous and intact. The only large-scale human disruption of inland habitat on Kodiak Island, the Terror Lake hydroelectric project, was completed with minimal direct or indirect adverse impact to bears or their habitat due to a conscious effort to work with and around the bears. Coastal areas have much greater human activity that influences bear activities, but it is generally restricted to isolated areas and small numbers of people. Eastern Afognak Island has a complex web of logging roads that are not open to motorized public access.
Commercial fishing is vital to the economy of the region. Fishing and fish processing occur year-round, but during summer months residents and transients expand their activities to remote coastal areas in pursuit of salmon. Salmon management for sustained yield is a high priority on the archipelago, and bear predation was factored into escapement rates. Residents of Kodiak generally have a higher tolerance and a greater understanding of bears than most other people. There is an on-going effort by various agencies to educate residents and visitors about bears, minimize attracting bears to human habitat, and maintain a lower bear density on northeastern Kodiak Island where most human activities occurs.
