Scent communication behavior by giant pandas

Behavioral strategies used in scent communication can reflect the adaptive capacity of animals. Signal detection theory and the principle of least effort posit that scent marking must be efficient and energy maximizing. The giant panda (Ailuropoda melanoleuca) is a solitary species that relies heavily on scent communication. There have been few studies on scent communication of wild pandas due to their elusive nature. To deepen the understanding of scent communication in this vulnerable species, we analyze a novel dataset obtained from integrating transect surveys on scent marked trees with infrared camera trapping of wild giant pandas performing scent marking and scent investigation behaviors. We found that pandas selected large coniferous trees for scent marking relative to what was available. Of the scent marked trees, trees that were more frequently marked than others were those of preferred species, high elevation, at topographical aspects conducive for odor transmission, with larger surrounding trees, and at gentle slopes. There were three peaks in the frequency of scent communication throughout the year in October, December, and March, the third period overlapping with the mating season. Scent communication occurred mainly during daytime hours, peaking at dusk (18:00–20:00). Frequency of anogenital gland secretion (AGS) markings were significantly greater than urine markings during the mating season but not during other times of year, which may reflect their stronger capacity to convey estrus state of females during mating season. The findings enrich the understanding of giant panda scent communication, and more broadly emphasize the importance of considering scent communication for conservation efforts such as corridor design for this vulnerable species.