It is estimated that 100,000 mountain goats live in North America. They occupy steep mountain ranges from the Cascade and the Rocky Mountains to Southcentral Alaska. Mountain goats occur naturally in the Southeast Panhandle and north and west to Cook Inlet. In Southcentral Alaska, goats can be found in the Chugach and Wrangell Mountains. Mountain goats have been successfully introduced to Baranof Island and Kodiak Island.
From 1952 to 1953, eleven female and seven male goats were transplanted from the Kenai Peninsula to Hidden Basin near the head of Ugak Bay, approximately 30 miles from the town of Kodiak. After a few severe winters, it was uncertain whether any of the transplanted goats had survived, but a 1964 aerial survey counted 26 goats. By 1972, biologists estimated that 100 goats lived on the island. By 2004, the population was estimated at 1560 goats, and by 2013, it had increased to 2500 animals. Goats now occupy every suitable habitat on Kodiak, and biologists are concerned that there are too many goats for the habitat to sustain.
While steep mountain cliffs are barriers to most animals, they are the preferred habitat of goats. Forested valleys, on the other hand, tend to be barriers to goats, because goats live not only where they can find an adequate food supply but also where they can quickly and easily escape predators such as bears. The steep slopes where goats live are easy for them to maneuver but are inaccessible to predators.
Mountain goats are both grazers and browsers. They eat sedges, ferns, mosses, and lichens. They spend their summers in the high alpine meadows where they consume sedges, forbs, and shrubs. During the winter when there is less food available, goats eat whatever they can find, including blueberry, hemlock, and lichens. Recent research on Kodiak indicates that fern rhizomes are an important part of the goats’ diet in early summer before and during vegetative green-up, but as the summer progresses, goats switch from ferns to sedges and forbs. Goats particularly seem to favor feeding sites with abundant long-awned sedge.
Mountain goats live an average of twelve years but may live as long as eighteen years. They inhabit an extreme environment that harbors a number of threats. Some of the main causes of death for goats include malnutrition, bear and wolf predation (although on Kodiak, there are no wolves), avalanches, falling, and human hunters. The ability to survive the winter depends on the goat’s body condition in the fall and the winter food supply. Mortality spikes in October during the first snowfalls and biologists surmise this is probably due to avalanches and the risks of traveling between summer and winter ranges, possibly through bear habitat. There is an even larger spike in mortality in late winter when malnutrition becomes a greater threat. Mortality also tends to be higher after a hot summer, and this may be because the most nutritious forage occurs at the edges of snow patches. If it is cooler and the snow recedes more slowly, the period of early-growth sprouting lasts longer than it does when the temperatures are warmer, and all the snow melts at once. Warm summers also cause heat stress.
The goat population on Kodiak continues to grow, and mountain goats have dramatically expanded their range in recent years. Introduced species like mountain goats can have negative impacts on native plants and animals, and biologists are concerned that a high density of mountain goats could adversely impact alpine areas where the slopes are steep, and there is not much soil. There is very little vegetation in this habitat, and goats could easily over-graze the plants that are there. Not only could over-grazing be irreversibly detrimental to the habitat, but it could and probably would cause a crash in the goat population. Researchers are trying to determine how many goats the alpine habitat on Kodiak can support, or in scientific terms, they want to find the carrying capacity for mountain goats on Kodiak. Biologists are concerned that mountain goats may have already exceeded their carrying capacity on the island, and current ongoing research by the U.S. Fish and Wildlife Service and the Alaska Department of Fish and Game is focused on better understanding exactly what and how much a goat eats over the course of a year.