Intrapopulation differences in polar bear movement and step selection patterns

Area of Science:

• Ecology
• Wildlife Biology
• Spatial Ecology

Background:

• Individual spatial ecology varies significantly within species.
• Understanding these variations is crucial for predicting population responses to environmental changes and human activities.
• Previous polar bear (Ursus maritimus) spatial ecology studies primarily used data from adult females due to tagging limitations.

Purpose of the Study:

• To evaluate class-specific movement and step selection patterns in polar bears.
• To compare movement and step selection between adult males, sub-adults, and adult females without cubs-of-the-year.
• To determine the suitability of using adult female data as a proxy for other polar bear classes.

Main Methods:

• Hierarchical Bayesian models were developed to analyze polar bear movement (step length, directional persistence) and step selection.
• Data were analyzed at a 4-day step length scale.
• Movement and step selection parameters were compared across adult males, sub-adults, and adult females without cubs-of-the-year.

Main Results:

• Adult males exhibited longer step lengths and less directed movements compared to adult females.
• Sub-adult movement parameters were similar to adult females but did not significantly differ from other classes.
• No significant differences in step selection parameters were detected among polar bear classes.

Conclusions:

• Step selection patterns of adult females can be used as a proxy for other polar bear classes during spring.
• Movement patterns of adult males differ significantly from adult females, making female data an inappropriate proxy for male movements.
• Further research is needed to assess movement and step selection differences across seasons and for other polar bear classes.