| Studies
by George Schaller, Hu Jinchu, and others suggested that the giant panda
is essentially solitary in nature. They found that males and females
rarely interact except during the breeding season. At this time, males
may also meet in the neighborhood of a female in heat, when they show a
dominance hierarchy.
But,
based on a study of radio-collared giant pandas in the Qinling
Mountains, Pan Wenshi and Lu Zhi, of the Beijing University, recently
suggested a somewhat different picture of panda social life. They found
that seven to 15 individuals may form a social community of pandas
within the local population. These individuals occupy a
"group" territory, within which male home ranges overlap
almost completely while female home ranges overlap far less. Members of
different "groups" generally avoid socializing with each
other.
These
exciting new results suggest that giant pandas are far more social than
we previously believed, and also raises important questions about
whether mating occurs exclusively between members of these small groups.
If so, and if pandas in other mountain ranges have similar social
groups, we will need to reevaluate our interpretation of the giant
panda’s genetic example, a mating system that is restricted to
"group" members would likely result in giant pandas being
genetically inbred in local populations. Yet, genetic analysis of blood
from a small number of giant pandas, performed by Steven O’Brien of
the National Cancer Institute, showed that the species retains
considerable genetic diversity. Clearly, this is a question that
requires further study, because the answers could have a significant
impact on conservation strategies.
The Pan
and Lu findings are similar to some behavioral observations made on
giant pandas in zoos and reserves. First, males can be maintained in
small groups without aggression if the males have been very carefully
introduced to one another. Usually the males develop a clear dominance
hierarchy. Second, female giant pandas seem to prefer mating with
specific males, usually males that they have known well for a long time.
They seek out the preferred male or males during estrus, using a series
of very elaborate vocalizations and behaviors that to a human seem
almost coy.
The
behavior patterns that giant pandas use to communicate with each other
reflect the dense habitat in which interactions occur, and the generally
low level of sociality. Visual signals - body language, facial
expressions, ear and mouth movements - are exceedingly rare because the
dense bamboo understory restricts vision and visibility. In addition,
massive cheek teeth and masseter muscles make subtle mouth, ear, and eye
movements virtually impossible.
In
contrast, giant pandas use vocalizations and sounds extensively in
social interactions. Indeed, the subtleties of expression that can be
seen in the faces of many primates can be heard in the gradations of
sounds and the combinations and recombinations of vocalizations of giant
pandas. Listening to the complexity of communication between Ling-Ling
and Hsing-Hsing during social and sexual encounters always awes me.
Giant pandas also use scent to communicate. They rub the large gland
that covers their anogenital region on objects, often at the edge of
their territory, where a thick, waxy, strong-smelling deposit soon
builds up. Both males and females may also urinate at marking sites,
adding additional odor information. Most scent marks are placed at nose
level or higher. Giant pandas use complex scent-marking postures to
deposit urine and secretions at different heights; they even perform
hand stands to raise their posteriors to make elevated scent marks.
At
minimum, based on odor alone, a giant panda can probably identify the
sex, age and individual identity of the scent marker, as well as
interpret the marker’s mood and reproductive status at the time it
left the scent mark. Because the scent is not ephemeral, as sounds are,
giant pandas may be able to tell not only who has visited a particular
site and how he or she was feeling, but when the visit occurred! Thus,
giant pandas accomplish with scents and sounds what we accomplish with
visual and auditory signals.
|