Publications (3)6.94 Total impact
Article: Sleeping Parties and Nest Distribution of Chimpanzees in the Savanna Woodland, Ugalla, Tanzania[show abstract] [hide abstract]
ABSTRACT: We conducted ecological studies of chimpanzees (Pan troglodytes) in the Ugalla area, western Tanzania. Ugalla is one of the driest habitats of chimpanzees and the Ugalla River is the eastern boundary of chimpanzee distribution. Most of Ugalla is occupied by savanna woodlands dominated by deciduous trees of Brachystegia and Julbernardia. Chimpanzees tended not to make nests in riverine forests in plains, but in small patchy forests dominated by Monopetalanthus richardsiae and valley forests dominated by Julbernardia unijugata on slopes in mountainous areas. We estimated population density of chimpanzees to be 7–9 × 10−2 individuals/km2 based on nest censuses, suggesting that 2–3 × 102 individuals inhabited the 3352km2 area of Ugalla. The size of the largest nest cluster (n=23) suggests that 1 unit group (community) comprised 30–35 individuals. In the daytime, chimpanzees formed small feeding parties (mean 2.0 individuals), but larger ones in the evening (mean 4.8 individuals and 5.2 individuals based on fresh nest clusters). The pattern might reduce the predation risk from large nocturnal carnivores such as lions and leopards. The sleeping sites may function as both a safe sleeping site and a meeting point for chimpanzees with a huge home range that may have difficulty in finding other members of their unit group.International Journal of Primatology 04/2012; 28(6):1397-1412. · 1.54 Impact Factor
Article: High prevalence of simian immunodeficiency virus infection in a community of savanna chimpanzees.[show abstract] [hide abstract]
ABSTRACT: Simian immunodeficiency virus of chimpanzees (SIVcpz) has a significant negative impact on the health, reproduction, and life span of chimpanzees, yet the prevalence and distribution of this virus in wild-living populations are still only poorly understood. Here, we show that savanna chimpanzees, who live in ecologically marginal habitats at 10- to 50-fold lower population densities than forest chimpanzees, can be infected with SIVcpz at high prevalence rates. Fecal samples were collected from nonhabituated eastern chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley (n = 375) and Shangwa River (n = 6) areas of the Masito-Ugalla region in western Tanzania, genotyped to determine the number of sampled individuals, and tested for SIVcpz-specific antibodies and nucleic acids. None of 5 Shangwa River apes tested positive for SIVcpz; however, 21 of 67 Issa Valley chimpanzees were SIVcpz infected, indicating a prevalence rate of 31% (95% confidence interval, 21% to 44%). Two individuals became infected during the 14-month observation period, documenting continuing virus spread in this community. To characterize the newly identified SIVcpz strains, partial and full-length viral sequences were amplified from fecal RNA of 10 infected chimpanzees. Phylogenetic analyses showed that the Ugalla viruses formed a monophyletic lineage most closely related to viruses endemic in Gombe National Park, also located in Tanzania, indicating a connection between these now separated communities at some time in the past. These findings document that SIVcpz is more widespread in Tanzania than previously thought and that even very low-density chimpanzee populations can be infected with SIVcpz at high prevalence rates. Determining whether savanna chimpanzees, who face much more extreme environmental conditions than forest chimpanzees, are more susceptible to SIVcpz-associated morbidity and mortality will have important scientific and conservation implications.Journal of Virology 07/2011; 85(19):9918-28. · 5.40 Impact Factor
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ABSTRACT: Surveys were carried out for chimpanzees, Pan troglodytes schweinfurthii, in the areas of Ntakata (300 km² between the Mkamba River and the Lubalisi River, 05°45′ –06°15′ S, 30°00′ –30°15′ E), and Kakungu (200 km² between the Lubalisi River and the sources of the Rubufu River, 05°55′ –06°15′ S, 30°00′ –30°15′ E), Tanzania, during the dry seasons of 2001 and 2003. The predominant vegetation was savanna woodland with forest patches (mainly along watercourses and hillsides). Population informa-tion was obtained by sightings and sleeping-nest counts. In the Ntakata area, chimpanzees occur in Ntakata, Mlofwezi, Kapalagulu (05°52′ S, 30°02′ E), and Mpulumuka (5°58′ S, 30°11′ E) and in the Ntakata-Kapalagulu Hills (Fig. 1). No evidence was forthcom-ing for their existence in Ikubulu, Lunfampa, Kakundu, Kabufisa, and Kamafiga, nor the plains of north of Kapalagulu Hill and the entire Lugufu basin. In the Kakungu area, they occur at Kakungu itself (05°58′ S, 30°03′ E) and Kalobwa in the Kakungu-Kalobwa Hills. With evidently large home ranges, densities were found to be low in the 500-km² area between the Ntakata-Kapalagulu Hills and Kakungu-Kalobwa Hills — everywhere less than 0.05(0.048) individuals/km². Hunting (by immigrant farmers and refugees), besides habitat loss (logging, firewood, and clearing for agriculture) are believed be causing a steady decline of chimpanzee popu-lations in the region.