부산대학교 도서관

Chimpanzees were once thought to sleep primarily in the trees, but recent studies indicate that some populations also construct terrestrial night nests. This behavior has relevance not only to understanding the behavioral diversity of Pan troglodytes, but also to the conservation of the species, given that nest encounter rates are often used to estimate great ape population densities. A proper estimate of decay rates for ground nests is necessary for converting the encounter rate of nests to the density of weaned chimpanzees. Here we present the results of the first systematic comparative study between the decay rates of arboreal and terrestrial chimpanzee nests, from the Bugoma Central Forest Reserve in western Uganda. We followed the decay of 56 ground and 51 tree nests in eight nest groups between April 2020 and October 2021. For 15 of the ground and 19 of the tree nests, we collected detailed information on the condition of the nests every two weeks; we checked the remaining 73 nests only twice. On average, ground nests lasted 238 days versus 276 days for tree nests (p = 0.05). Of the 107 total nests surveyed, 51% of tree and 64% of ground nests had disappeared after six months. Based on our results, we propose a modification of the formula used to convert nest density into chimpanzee density. Our results highlight the importance of taking into account potential differences in decay rates between ground versus tree nests, which will likely influence our understanding of the distribution of ground nesting behavior in chimpanzee across tropical Africa, as well as our estimations of the densities of ground nesting populations. Research Highlights: Our logistic regression model based on 55 ground and 49 tree nests showed that, on average, ground nests decayed 38 days before tree nests, a significant difference. If this pattern is similar in other areas, it has implications for the documentation of ground nesting in chimpanzee populations as well as chimpanzee density estimations.Nests we followed over the course of the study which had been constructed using the tree species Omusetera (Maeruasp.) had not disappeared after one year.In a subset of 15 ground and 19 tree nests, terrestrial nests reached a more decayed age category more rapidly than arboreal nests. This difference may be related to the plant species used in nest construction.In areas in which chimpanzees nest frequently on the ground, we propose an update to the formula commonly used to estimate chimpanzee densities: the nest decay rate term should be weighted by the percentages of ground and tree nests counted. [ABSTRACT FROM AUTHOR]