Abstract # 38:

Scheduled for Thursday, June 17, 2010 07:00 PM-09:00 PM: Session 11 (Medallion Ballroom C/D/E/F) Poster Presentation


EFFECTS OF TREE CHARACTERISTICS ON SLEEPING TREE CHOICE IN BORNEAN AGILE GIBBONS (HYLOBATES ALBIBARBIS)

J. R. Rinear1, L. K. Sheeran1 and S. M. Cheyne2,3
1Central Washington University, Ellensburg, WA 98926, USA, 2Orangutan Tropical Peatland Project, 3University of Oxford
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Unlike other apes, hylobatids do not construct sleeping nests. Instead, these arboreal primates sleep in the forest canopy. Previous gibbon research indicates that certain aspects of tree morphology and interaction with surrounding flora can both positively and negatively affect the sleeping tree choices of Hylobates lar and H. klossi. We tested the hypotheses that  (1) gibbons are selective about sleeping trees, and (2) gibbons prefer sleeping trees with characteristics that reduce chances of predation. From October 2005-September 2009 data were collected from H. albibarbis sleeping trees at the Natural Laboratory of Peat Swamp Forest, Sabangau Catchment, Central Kalimantan, Indonesia. We recorded dimensional measures and qualitative features for each sleeping tree [n=45] and for four surrounding control trees [n=180]. We found that tree height is associated with tree selection [Binary Logistic Regression: z=2.04, P=0.04]. Gibbons appear to avoid trees with lianas [Binary Logistic Regression: z= -1.75, P=0.08], and also avoid trees with predator access to the crown via neighboring trees [Binary Logistic Regression: z= -1.96, P=0.05]. Our results are consistent with previous findings that the gibbons prefer taller trees and those with fewer lianas. Our findings also underscore the importance of retaining large trees in mixed-swamp forest and give insight into the anti-predatory behavior of this gibbon species.