Abstract # 157:

Scheduled for Friday, August 19, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation


QUANTIFYING THE POSITIONAL BEHAVIOR OF DIADEMED SIFAKAS (Propithecus diadema) AND THE EFFECTS OF FOREST STRUCTURE ON SUPPORT USE

K. Samonds1, J. Raharison2 and M. Irwin3
1Stony Brook University, Department of Anatomical Sciences, Stony Brook, NY 11794-8081, USA, 2Université d’Antananarivo, Antananarivo, Madagascar, 3Dept. of Anthropology, Stony Brook University
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     The ability to employ a large range of postures is thought to be advantageous in acquiring food, but this suggestion has not been adequately tested. Propithecus diadema is described as suspending in feeding contexts, but the extent and type of suspensory behaviors have not been examined. We quantified the postural repertoire of P. diadema, and tested whether postures differed between forest types. Four P. diadema groups were observed in the eastern rainforests of Tsinjoarivo, Madagascar: two in continuous forest and two in small, degraded fragments. Data were collected during fifteen all-day focal follows (15 individuals, 1 follow each), using instantaneous samples (1-min interval); daily averages were used in analyses to ensure independence. Each observation recorded the animal’s activity, height, position, number of limbs involved, and size and orientation of each substrate. Sitting was the most common posture (68%), followed by clinging (28%), and suspension was rare (2%). During feeding, sitting was used less (56%), while clinging (38%) and suspension (4%) were used more. In 29% of feeding samples, ≥ 3 supports were used. While heights used were significantly higher in pristine forest (Mann-Whitney U-test, n = 15, P = 0.001), there were no significant differences between sites in the use of specific postures (G-test, n = 15, ns) and substrates (M-W U-test, n = 15, ns). Surprisingly, P. diadema’s postural repertoire is highly conservative between forest types, despite large differences in vegetation structure.