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KODIAK: Refuge Evaluates New Deer Survey Method
Alaska Region, October 15, 2012
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Location of the Aliulik Peninsula study site on Kodiak Island, Alaska.
Location of the Aliulik Peninsula study site on Kodiak Island, Alaska. - Photo Credit: McCrea Cobb/FWS
Sitka black-tailed deer at Kodiak National Wildlife Refuge, Kodiak Island, Alaska.
Sitka black-tailed deer at Kodiak National Wildlife Refuge, Kodiak Island, Alaska. - Photo Credit: D Menke

After living through one of the toughest winters on record, many Alaskans are asking the same questions: How does winter impact game populations? Is the population higher or lower than last year? These are some questions that biologists from Kodiak Refuge are seeking to address for Kodiak Island, through a novel study aimed at quantifying Sitka black-tailed deer abundances.

 

Sitka black-tailed deer were introduced to Kodiak Island, Alaska, from Sitka, in 1924 to provide residents with additional hunting opportunities. The deer population thrived and subsequently expanded to include most of the Kodiak Archipelago. Currently, Kodiak Refuge is the only National Wildlife Refuge in Alaska with Sitka deer, and this is the western-most outpost of the species’ distribution. Although determining changes in deer abundances is fundamental to science-based harvest management, surveying Kodiak’s deer has been a substantial challenge because the population inhabits wide array of habitats, ranging from areas dominated by dense Sitka spruce forest, to areas dominated by crowberry heath.

As part of a larger project to overcome this obstacle, Kodiak Refuge biologists are exploring the utility of using distance sampling techniques applied to aerial surveys to estimate deer abundance in non-forested habitats. The technique, which has been used to count other species such as pronghorn antelope in Montana and moose in Alaska, involves counting wildlife from a plane. The observer then also records the horizontal distance to deer groups (aided by marks on the struts of the plane), the deer’s habitat, and the deer’s behavior (for example, standing or bedded). By plugging these variables, associated with each deer group, into a statistical software package, Refuge biologists are able to estimate the number of deer missed during surveys, and use this information to produce a corrected estimated of deer abundance with a measure of statistical confidence.

In May 2012, Kodiak Refuge biologist, McCrea Cobb, conducted the first aerial surveys for deer on Kodiak using the distance sampling approach. The Aliulik Peninsula in southern Kodiak Island was selected as the study site to evaluate the utility of the method to estimating deer in non-forested habitats of Kodiak. The results of the survey effort showed that the method can be successfully applied to estimating deer on tundra, grassland and shrub habitats. Based on these results, Refuge biologists plan to expand the survey area to include a wider range of representative non-forested areas on Kodiak Island.

Providing local residents with the opportunity to continue their subsistence uses is a primary goal of the Kodiak Refuge. Since deer are a central subsistence species for the local community, meeting this goal requires maintaining a viable deer harvest. Having an estimate of the number of deer available for harvest will be a critical step toward improved harvest management.


Contact Info: McCrea Cobb, 907-487-0246, mccrea_cobb@fws.gov



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