Modeling Caribou Movements: Seasonal Ranges and Migration Routes of the Central Arctic Herd

Area of Science:

• Ecology
• Wildlife Biology
• Conservation Science

Background:

• Large-scale terrestrial animal migrations face increasing challenges due to habitat fragmentation and human-induced obstacles.
• The migratory patterns and seasonal distributions of the Central Arctic herd (CAH) of barren-ground caribou (Rangifer tarandus granti) in northern Alaska were not well-documented.

Purpose of the Study:

• To document the seasonal distributions and migratory movements of the Central Arctic herd (CAH) of caribou in northern Alaska.
• To identify critical habitats and migration corridors essential for the long-term persistence of this migratory species.

Main Methods:

• Utilized GPS radio-collars on 54 female caribou from the CAH between 2003 and 2007.
• Employed Brownian bridges to model annual fall and spring migrations, averaging results over four years to identify consistently used areas.
• Calculated seasonal range sizes using 90% fixed kernel utilization distributions.

Main Results:

• Annual summer and winter seasonal ranges were similar in size (approx. 27,929 km² and 26,585 km², respectively).
• Overlap between consecutive summer ranges (62.4%) was significantly higher than between consecutive winter ranges (42.8%).
• Identified multiple migration routes, with several areas showing consistent use by caribou across all study years.

Conclusions:

• Conservation efforts should prioritize the protection of repeatedly used migration routes and seasonal ranges to support caribou persistence.
• Understanding caribou movements and potential threats is crucial for maintaining migratory pathways and habitats in the face of environmental change.
• Proactive management of identified critical areas can facilitate the long-term survival of migratory species like the Central Arctic caribou herd.