1Department of Anthropology, Washington University in Saint Louis, 2Office of the Dean, Kansas State University
March 28, 2015 , Gateway Ballroom 2/3/4/5
Several advantages exist for primates who remain in the same home range over time. These advantages include access to known resources and increased foraging efficiency through the development of established travel routes. We examined the demographic changes and shifts in home range location of 5 groups of habituated indri (Indri indri) and 2 groups of habituated diademed sifakas (Propithecus diadema) in Betampona Nature Reserve (BNR), Madagascar. Group demographic data and all-occurrences of feeding were recorded for each group in 2008, 2009 and 2013-14. All feeding locations were marked with a GPS waypoint. In addition to keystone sleeping and movement substrates, we used these waypoints to quantify home range location and overlap over time. The results suggest that sifaka and indri groups in BNR are ecologically and socially flexible. Both the group size and composition fluctuated over time, as did the home range size and habitat inclusion. Overall, diademed sifaka home ranges were larger than that of indri. We found that groups with demographic changes in the form of the addition or subtraction of adult individuals experienced greater fluctuations in the location of their home range than groups with stable adult membership. In several cases a shift was made to an entirely new area without the incorporation of the previous home range. Indri and sifaka behavioral plasticity observed in BNR allows these species to continue to co-exist in this small forest fragment.