Behavioural flexibility in migratory behaviour in a long-lived large herbivore

Area of Science:

• Ecology
• Animal Behavior
• Wildlife Management

Background:

• Migratory behavior in animals is often assumed to be a fixed trait, particularly in large mammals.
• Limited research has explored individual-level behavioral plasticity in migratory ungulates using long-term data.
• Understanding migratory flexibility is crucial for predicting population dynamics and fitness.

Purpose of the Study:

• To investigate individual variability in migratory behavior within a partially migratory elk (Cervus elaphus) population.
• To identify intrinsic, environmental, and density-dependent factors influencing migratory decisions and strategy switching.
• To assess the implications of behavioral plasticity for the maintenance of partial migration.

Main Methods:

• Utilized a 10-year telemetry dataset of 223 adult female elk.
• Classified migratory strategy (migrant vs. resident) using net squared displacement (NSD) for each individual elk-year.
• Analyzed the influence of climate, predator-prey abundance, age, and population density on migration probability and strategy switching.

Main Results:

• Elk individuals switched between migratory and resident strategies at a mean rate of 15% annually.
• Migration probability increased with severe winters, higher wolf abundance, and older age.
• Strategy switching was density-dependent: migrants became residents at low elk density, while residents became migrants at high elk density.

Conclusions:

• Migratory behavior in ungulates is a plastic, individually variable trait.
• Behavioral plasticity in elk responds dynamically to environmental, intrinsic, and density-dependent factors.
• Opposing responses to drivers stabilize partial migration and support demographic fitness in the studied population.