Behavioral Development of Polar Bear Cubs
Polar bear (Ursus maritimus) cubs are born blind, deaf, hairless, and weighing less than one pound. For the first three to four months, cubs remain exclusively in the maternal den. Even after their initial den emergence, maternal groups may continue to spend extended periods of time in the den. In the wild, there is no way to observe mother-cub behavior or cub development in the den. Due to these challenges, most wild cub research has focused on survival, while captive cub research has focused on hand-rearing and weight-charting. Some accredited zoos have equipped their denning spaces with audio and infrared cameras to learn more about this crucial developmental period. On November 17, 2020, adult female Suka gave birth to two cubs at the Detroit Zoo. One cub (Laerke) was hand-reared out of medical necessity, while the other cub (Astra) remained with Suka to be mother-reared. Cameras mounted in Suka’s maternal den and the extraordinary dedication of animal care staff allowed for continuous 24-hour monitoring of Suka and Astra throughout Astra’s first 12 weeks of life. This comprehensive and unprecedented monitoring allowed us to track Astra’s patterns of nursing, rest and increasing independence during the critical neonate phase. Although our sample size is small, these data make a significant contribution to establishing species-general patterns of development. We were able to continue this developmental monitoring with both Astra and Laerke after Laerke had been medically stabilized. Between the ages of 14 and 24 weeks, we conducted 12, 5-minute observations per observation day. We were able to use the resulting data to examine shifts in rest, locomotory and independent play behaviors. Despite their differences in rearing environments, Astra and Laerke demonstrated remarkably comparable daily and hourly patterns of behavior. These data were promising for Laerke’s growth trajectory as a healthy, independent, young polar bear. We continue to process a wealth of data we collected on the polar bear cubs throughout their residence at the Detroit Zoo, and we look forward to sharing it with the community in pursuit of excellent welfare.