Camera-traps capture wild chimps' nighttime raiding activities

Wild chimpanzees living in disturbed habitat may use innovative strategies, like foraging crops at night, to coexist with nearby human activities, according to a study published October 22, 2014 in the open-access journal PLOS ONE by Sabrina Krief from Muséum national d'histoire naturelle and colleagues.

People expanding land use for agriculture and other activities are increasingly encroaching on wild chimpanzee habitat. To understand how chimpanzees are adjusting, researchers used camera-traps to observe chimpanzee behavior during incursions out of the forest into maize fields in Kibale National Park, Uganda. During the 20 days of the study, a total of 14 crop-raiding events were recorded by the activation of the video-trap.

The researchers observed large parties of ~8 chimpanzees more than double the median of the party size of 3 chimps of the same community during feeding activities in the forest. These groups also included vulnerable individuals such as females with clinging infants. The video-traps also captured the chimpanzees crop-raiding during the night, a previously undocumented and normally a risky behavior. They also stayed longer in the maize field and presented few signs of vigilance and anxiety during these nighttime crop-raids. While nocturnal activities of chimpanzees have been rarely reported during full moon periods, this is the first record of frequent and repeated activities at night, in the darkness. Habitat destruction may have prompted the chimpanzees to adjust their normal behavior to include innovative behaviors exploiting open croplands at night.