Variation in movement patterns of mule deer: have we oversimplified migration?

Area of Science:

• Wildlife Ecology
• Animal Behavior
• Conservation Biology

Background:

• Migratory animal research often overlooks atypical behaviors, focusing on simple distance and timing metrics.
• Understanding the full spectrum of migratory strategies is crucial due to threats from development and climate change.

Purpose of the Study:

• To characterize the variation in migration strategies, including atypical behaviors, in Utah mule deer (Odocoileus hemionus).

Main Methods:

• Developed novel methods beyond traditional metrics to categorize migratory behaviors based on range use and shifts.
• Analyzed movement trajectories to classify strategies like dual-range, multi-range, commuter, poly-migrant, gradual mover, resident, and disperser.
• Examined annual shifts in migratory categories for individual deer.

Main Results:

• Classified 1218 trajectories from 722 female mule deer, revealing significant behavioral diversity.
• Identified 54.4% as dual-range migrants, 23.6% as multi-range migrants, and 12.6% as residents.
• Found that 51.2% of deer monitored over multiple years switched migratory categories.

Conclusions:

• Atypical migratory strategies are common in mule deer, highlighting the need to study less-stereotyped behaviors.
• The diversity in migration strategies and category switching suggests complex drivers and has implications for conservation planning.