Mentasta Caribou Herd Monitoring

AITRC works with Cheesh’na Tribal Council and Wrangell-St. Elias National Park and Preserve to monitor the Mentasta Caribou Herd and better understand population dynamics, habitat use, calf survival, and recruitment. By combining GPS collar data, aerial surveys, biological samples, and long-term monitoring, this project provides information needed to understand factors affecting the herd and support informed management of this important subsistence resource.

Funded by the U.S. Fish and Wildlife Service Tribal Wildlife Grants Program and the Bureau of Indian Affairs, in partnership with Cheesh’na Tribal Council and Wrangell-St. Elias National Park and Preserve

About the Mentasta Caribou Herd.

The Mentasta Caribou Herd ranges across portions of the upper Copper River Basin, including areas within and surrounding Wrangell-St. Elias National Park and Preserve. Caribou have long provided an important subsistence resource for Ahtna communities and remain an important part of the region’s ecosystem.

The Mentasta herd has remained at a relatively low population density for more than 30 years. Understanding why the herd remains at these levels requires looking at multiple factors, including adult survival, calf production and survival, habitat use, nutrition, and interactions with predators.

AITRC’s monitoring helps build a clearer picture of how the herd is changing over time and provides locally relevant information that can contribute to long-term stewardship.

Caribou Collaring & GPS Monitoring.

GPS and radio collars allow researchers to follow individual caribou across a large and remote landscape. Adult female with GPS collars provide an important source of information for the project. AITRC supported fall 2024 capture and collaring efforts with WRST, resulting in 28 active GPS collars within the Mentasta Caribou Herd.

This will provide information on:

Seasonal movements and migration
Calving areas
Habitat use
Survival
Distribution of the herd throughout the year

Habitat Research.

AITRC has begun developing seasonal Resource Selection Function (RSF) and habitat suitability models using data from GPS-collared adult female caribou.

Initial summer habitat models showed clear habitat relationships, while analysis identified a need for additional winter-specific environmental information. Current research priorities include incorporating factors such as snow cover, snow depth and icing conditions, and winter vegetation availability into winter habitat models.

Together, summer and winter models are intended to improve understanding of how Mentasta caribou use habitat throughout the year.

Aerial Surveys.

Because the Mentasta herd occupies a large and remote area, aircraft are an essential research tool.

Researchers use aerial telemetry and GPS locations to find collared animals and conduct repeated observations during important periods of the caribou life cycle. During the spring calving season, these flights can document whether adult females have calves and whether those calves remain with them during subsequent surveys.

Repeated surveys provide information that cannot be obtained from GPS locations alone and help researchers evaluate survival and recruitment across the herd.

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Caribou Health & Biological Samples.

Caribou captures also provide opportunities to collect biological samples that can help researchers better understand animal health and nutrition.

AITRC and project partners are working with blood, serum, and hair samples collected from Mentasta and Chisana caribou. These samples can be used for nutrient analyses and provide additional information that complements movement, survival, and recruitment data.

Pairing biological information with GPS monitoring helps researchers look beyond where caribou travel to better understand the condition of individual animals and factors that may influence herd productivity.

Project Leads: Sterling Spilinek | Questions on this project?