The birth of the panda twins Fu Feng and Fu Ban in August 2016 opened up a unique opportunity for Schönbrunn Zoo to study for the first time the parental care of a mother panda with two cubs. These cubs were raised solely by the mother without any human support. Even today, all panda females that have given birth to twins in zoological facilities have either rejected one of the cubs or those cubs were intensively attended to by their animal keepers. This has led to the conventional wisdom that panda females are principally unable to raise more than one cub.
A detailed video analysis of the behavior of both the panda female and her cubs yields insights into the potential differences in mothers rearing one versus two cubs. The general opinion is that energetic constraints enable panda females to raise only a single young. This leads to the hypothesis that the maternal care differs when one or two cubs are involved. The assumption is that each cub of the twin pair will receive less motherly care that would a single cub.
Despite intensive research, many aspects of the reproductive strategy of Giant pandas remain unknown. This work provides the first evidence that Giant pandas can raise twins. Even though many panda twins survive today because the animal keepers spend a lot of time and energy exchanging the twins between the mother and the incubator, natural rearing by the mother is always preferable to hand-raising the young.
At Schönbrunn Zoo, the installation of a video-surveillance system in the nesting box enabled a 24-hour analysis of the behavior of the female and her two cubs. During the first three months of the twins’ lives, the amount of time the panda mother spent for care was precisely documented, whether this involved suckling them, cleaning them or otherwise interacting with them.
This study yielded astounding results. In contrast to expectations, Yang Yang devoted the same amount of time to each of her offspring as she would have devoted to a single cub. In order to accomplish this time-wise, she reduced her own resting periods. This study therefore disproves the opinion that energetic constraints principally prevent panda females from raising more than one offspring. The question which factors are decisive for Yang Yang’s achievement remains open.
A range of factors is no doubt involved. The experience Yang Yang gained in earlier pregancies clearly played a role. Moreover, Schönbrunn Zoo offered the panda mother the opportunity to retreat from the visitors and take care of her young in at undisturbed atmosphere. In the first weeks after the births, even the animal keepers were restricted to video observations and reduced their interventions to a minimum. A third, very important aspect is the birth-weight of the young. A cub born with a distinctly lower weight has considerably lower chances of survival.