Hair growth rate estimation in North American ursids

Area of Science:

• Zoology
• Wildlife Ecology
• Animal Physiology

Background:

• Bear feeding ecology significantly impacts population dynamics, cub survival, and distribution.
• Current understanding relies on tissue analysis, harvested animals, or non-invasive methods.
• Inferring bear diet from hair is limited by a lack of data on moult timing and hair growth rates.

Purpose of the Study:

• To develop and test two novel methods for quantifying hair growth rates in ursids.
• To assess individual and seasonal variations in bear hair growth.
• To establish a foundation for analyzing seasonality in wild-collected bear hair samples.

Main Methods:

• Two safe, non-invasive methods were tested on polar, black, and grizzly bears in a zoo setting.
• Methods included applying hair dye/bleach and feeding isotopically labeled amino acid capsules.
• Hair samples were collected bi-weekly for five months from consistent body locations.

Main Results:

• Both visual (dye/bleach) and biochemical (amino acid) methods effectively quantified hair growth rates.
• Individual and seasonal variations in hair growth were detected across species.
• Average guard hair growth rates ranged from 0.10 to 1.05 mm/day.

Conclusions:

• The developed methods provide a reliable way to measure bear hair growth rates.
• This research enables the incorporation of seasonal hair growth data into ecological studies.
• Findings contribute to a better understanding of ursid population dynamics and health.