Effects of water level on sleeping‐site selection and inter‐group association in proboscis monkeys: why do they sleep alone inland on flooded days?
Tóm tắt
A one‐male group (BE‐Group) of proboscis monkeys was studied along the Menanggul River, a tributary of the Kinabatangan River, Sabah, Malaysia, from May 2005 to 2006. It has generally been assumed that proboscis monkeys only set up their sleeping sites along the riverbank; however, when more than 1 m of water covered the forest floor for more than 700 m inland from the riverbank during the seasonal flood, the BE‐Group slept inside the forest. It seems that the sleeping‐site selection of the BE‐Group was not influenced by food availability during the flooded months because the food availability by the vegetational survey did not vary much between flooded and non‐flooded months. In addition, feeding behaviors of the focal monkey in the BE‐Group also did not vary much between flooded and non‐flooded days. On the other hand, the water level statistically influenced the sleeping‐site selection. The proboscis monkeys remained in inland forest during the flooded days because of the reduced predation threat, as terrestrial predators such as clouded leopards are prevented from foraging by deep water covering the forest floor. On non‐flooded days when the BE‐Group slept at the riverbank, they frequently slept close to other one‐male groups on the riverside trees. Contrastingly, when the group slept inside the forest on flooded days when the water level was high, they slept away from other groups. This difference in the need for one‐male groups to sleep close to each other might be attributed to the decreased predation threat during high water level in the flooded days.
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Tài liệu tham khảo
Altmann SA, 1970, Baboon ecology: African field research
BrodieJF Brockelman(2009)Bed site selection of red muntjac (Muntiacus muntjak) and sambar (Rusa unicolor) in a tropical seasonal forest.Ecol Res(in press)
Buskirk SW, 1994, Martens, sables, and fishers: biology and conservation, 283
Cheney DL, 1987, Primate societies, 227
Dunbar RIM, 1986, Ecological aspects of social evolution, 332
Kummer H, 1971, Primate Societies: Group Techniques of Ecological Adaptation
Matsuda I, 2008, Graduate School of Environmental Earth Science
MatsudaI KuboT TuugaA HigashiS(2009)A Bayesian analysis of the temporal change of local density of proboscis monkeys: implications for environmental effects on a fission–fusion society.Am J Phys Anthropol(in press)
Miller LE, 2007, Primates in perspective, 525
Murai T, 2004, Graduate School of Environmental Earth Science
Oates JF, 1987, Primate societies, 197
Struhsaker TW, 1975, The red colobus monkey
Schaik CP, 1996, Evolution and ecology of macaque societies, 160
Yeager CP, 1993, Ecological constraints on intergroup associations in the proboscis monkey (Nasalis larvatus), Trop Biodivers, 1, 89