They remain largely unmotivated by supplemental food, as they still acquire many of their calories via maternal milk. Though nursing is rarely seen, the cubs’ behavior, coupled with Marcella’s obviously distended mammaries, indicate this is still a primary feeding method for the youngsters. Occasionally, I do see Marcella push a cub away when it tries to suckle, usually at a time when she is most interested in searching for her breakfast in the exhibit. When they are not sleeping, the cubs routinely engage in vigorous bouts of social play with each other. Palu, who is about 4 kilograms (8.8 pounds) larger than his sister, can be very physical in these play bouts. He tackles Pagi and paws at her wildly. Despite her smaller size, Pagi seems to set the tone for their play, often terminating the bouts when they get too rough. She loves to initiate bouts of “chase and flee” as she runs from her brother. It will be interesting to look at the data we have collected thus far and see what behavioral differences there are between young males and females. Our dataset currently includes two males and two females, two twins and two singletons. We know there are some differences in maternal behavior when comparing male cubs to female cubs in giant pandas, but such differences have yet to be explored in the sun bear.
Palu and Pagi are on exhibit every afternoon. Come enjoy them, along with Marcella, while they still retain their youthful exuberance!
Suzanne Hall is a senior research technician for the San Diego Zoo’s Institute for Conservation Research