title: Population status of chimpanzees in the Masito-Ugalla Ecosystem, Tanzania.
abstract: More than 75 percent of Tanzania's chimpanzees live at low densities on land outside national parks. Chimpanzees are one of the key conservation targets in the region and long-term monitoring of these populations is essential for assessing the overall status of ecosystem health and the success of implemented conservation strategies. We aimed to assess change in chimpanzee density within the Masito-Ugalla Ecosystem (MUE) by comparing results of re-walking the same line transects in 2007 and 2014. We further used published remote sensing data derived from Landsat satellites to assess forest cover change within a 5 km buffer of these transects over that same period. We detected no statistically significant decline in chimpanzee density across the surveyed areas of MUE between 2007 and 2014, although the overall mean density of chimpanzees declined from 0.09 individuals/km(2) in 2007 to 0.05 individuals/km(2) in 2014. Whether this change is biologically meaningful cannot be determined due to small sample sizes and large, entirely overlapping error margins. It is therefore possible that the MUE chimpanzee population has been stable over this period and indeed in some areas (Issa Valley, Mkanga, Kamkulu) even showed an increase in chimpanzee density. Variation in chimpanzee habitat preference for ranging or nesting could explain variation in density at some of the survey sites between 2007 and 2014. We also found a relationship between increasing habitat loss and lower mean chimpanzee density. Future surveys will need to ensure a larger sample size, broader geographic effort, and random survey design, to more precisely determine trends in MUE chimpanzee density and population size over time.
authors.affiliation: Department of Archaeology and Anthropology, University of Cambridge, Cambridge CB2 3QG, United Kingdom.|Ugalla Primate Project, Kigoma, Tanzania.
authors.forename: Alex K
authors.initials: AK
authors.lastname: Piel
authors.affiliation: Ugalla Primate Project, Kigoma, Tanzania.
authors.forename: Naomi
authors.initials: N
authors.lastname: Cohen
authors.affiliation: The Jane Goodall Institute, Kigoma, Tanzania.
authors.forename: Shadrack
authors.initials: S
authors.lastname: Kamenya
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Blindern, Oslo, Norway.
authors.forename: Sood A
authors.initials: SA
authors.lastname: Ndimuligo
authors.affiliation: The Jane Goodall Institute, 1595 Spring Hill Road, Suite 550 Vienna, Virginia.
authors.forename: Lilian
authors.initials: L
authors.lastname: Pintea
authors.affiliation: Department of Archaeology and Anthropology, University of Cambridge, Cambridge CB2 3QG, United Kingdom.|Ugalla Primate Project, Kigoma, Tanzania.
authors.forename: Fiona A
authors.initials: FA
authors.lastname: Stewart
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D065928:Forests; D009425:Nesting Behavior; D002679:Pan troglodytes; D011156:Population Density; D058998:Remote Sensing Technology; D013636:Tanzania
keywords: chimpanzee; density; masito-ugalla; remote sensing; survey; tanzania