Abstract # 131:

Scheduled for Sunday, September 20, 2009 05:00 PM-05:10 PM: Session 13 (Del Mar Room) Oral Presentation


A NEW TECHNIQUE FOR DETERMINING THREE DIMENSIONAL AND FOUR DIMENSIONAL HOME RANGE VOLUMES: AN UPDATE

L. J. Digby
Duke University, Dept. of Evolutionary Anthropology, Durham, NC 27708, USA
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Home range use is a key element in any field study of primate ecology. Yet traditional techniques call for a simple two-dimensional area of range use, even for those arboreal species that exist in a three-dimensional habitat. Here, I present a new technique for calculating three-dimensional (3D) home range “volumes” using familiar techniques and, where possible, readily available software. Data were collected on three semi-free ranging groups (3-6 individuals/per group)housed in a large (11+ ha) forested enclosure at the Duke Lemur Center in Durham, North Carolina. Using focal animal sampling and GPS units, we sampled height as well as latitude and longitude every 5 minutes. Results indicate that the groups had very similar 2D home range areas as calculated by traditional means [range 1.7-1.9ha]. But, each group differed substantially in their home range volumes [Lemur: 202,000 c3; Eulemur: 468,000 c3; Varecia: 576,000 c3], reflecting their differences in height use. We used a “stacked grid” calculation, but a stacked polygon method is also viable. We are also working on a 3D version of kernel estimators. With the miniaturization of GPS collars, allowing for location 24/7, we also hope to acquire four dimensional (4D) home range volumes (x, y, z and time). Current studies using this technique include investigating the impact of infants on home range volumes and variation across years with varying degrees of rainfall and forest disturbance.