Hair Growth Rate Estimation in North American Ursids

This study aimed to quantify hair growth rates in three species of North American bears (polar, black, and grizzly) using visual and biochemical methods in a zoo setting. The study involved 1 polar bear, 3 black bears, and 3 grizzly bears. Researchers applied hair dye or bleach and fed isotopically labeled glycine to mark hair growth, collecting samples every 1-2 weeks over five months. Results showed that both methods effectively identified hair growth periods and detected individual and seasonal variations, with average growth rates ranging from 0.10 to 1.05 mm per day. This research lays the groundwork for understanding seasonal hair growth in wild bears.