A non-native mountain goat on the Hepburn Peninsula of Kodiak Island, June 2012. - Photo Credit: A. Sensirirak/USFWS

Ian Petkash conducts a vegetation survey at a mountain goat feeding site, Kodiak Island, Alaska, June 2012. - Photo Credit: I. Petkash/USFWS

Researchers from Kodiak National Wildlife Refuge completed their second summer of study of mountain goat diet, feeding site preference, and habitat capacity. Mountain goats on Kodiak Island were introduced in 1952, and the population has since grown exponentially in size and range. Currently, mountain goat plays an important role in the sport and subsistence hunting community on Kodiak. However, such introduced species can have negative impacts on native plants and animals. High densities of mountain goats could adversely impact alpine summer range where soils are shallow, slopes are steep, and vegetation growth is limited. However, it is unknown whether mountain goats have impacted Kodiak’s native plants and animals.

This summer, our field research team revisited study sites and repeated data collection protocols established in 2011. To assess mountain goat preference of feeding sites, the team quantified the variety and amount of plant species at goat feeding and non-feeding sites. In addition, the team collected mountain goat pellet samples. These samples were later sent to a lab at Washington State University (WSU) to determine the variety and amount of plants in the diet. Results from feeding site preference and diet analyses will facilitate evaluation of potential differences related to population density and habitat.

Kodiak Refuge researchers added a new study component this year: determining the capacity of mountain goat habitats. The field work to achieve this goal involved two main tasks. First, the team collected samples of known plant foods that composed greater than 5% of mountain goat diets, as determined from the previous year’s diet study. Forage plants were then sent to WSU’s lab to determine their nutritional content. Secondly, the team clipped and collected plants within small plots at feeding and non-feeding sites. Each sample of plants from individual plots was later sorted to species, dried, and weighed to provide an estimate of relative forage weight by species. The Refuge plans to use the results from analyses of forage nutritional content and plant weights to assess the potential nutritional capacity of mountain goat habitats. This result, in combination with information about mountain goat daily nutritional requirements, will be used to predict the number of goats that can be supported by a given habitat.

Field work was conducted in remote locations, which provided substantial logistical difficulties and hardships. Kodiak Island is known for steep terrain, thick vegetation, and severe weather. Despite these obstacles the field crew comprised of a biological technician and three volunteers spent 53 days in the field, maintained high spirits throughout the summer, and successfully built upon our understanding of the one of North America’s least studied mammal species.

Eric Torvinen and McCrea Cobb