Disclaimer: Any opinion, finding, and conclusions or recommendations expressed in this material; are those of the author and do not reflect the views of the National Science Foundation.
Technical note: Tree truthing: How accurate are substrate estimates in primate field studies?†
Article first published online: 27 FEB 2012
Copyright © 2012 Wiley Periodicals, Inc.
American Journal of Physical Anthropology
Volume 147, Issue 4, pages 671–677, April 2012
How to Cite
Bezanson, M., Watts, S. M. and Jobin, M. J. (2012), Technical note: Tree truthing: How accurate are substrate estimates in primate field studies?. Am. J. Phys. Anthropol., 147: 671–677. doi: 10.1002/ajpa.22037
- Issue published online: 13 MAR 2012
- Article first published online: 27 FEB 2012
- Manuscript Accepted: 17 JAN 2012
- Manuscript Received: 19 MAY 2011
- AAPA professional development grant, Santa Clara University, Undergraduate Research Initiative
- positional behavior;
- substrate size;
- substrate angle;
- positional modes
Field studies of primate positional behavior typically rely on ground-level estimates of substrate size, angle, and canopy location. These estimates potentially influence the identification of positional modes by the observer recording behaviors. In this study we aim to test ground-level estimates against direct measurements of support angles, diameters, and canopy heights in trees at La Suerte Biological Research Station in Costa Rica. After reviewing methods that have been used by past researchers, we provide data collected within trees that are compared to estimates obtained from the ground. We climbed five trees and measured 20 supports. Four observers collected measurements of each support from different locations on the ground. Diameter estimates varied from the direct tree measures by 0–28 cm (Mean: 5.44 ± 4.55). Substrate angles varied by 1–55° (Mean: 14.76 ± 14.02). Height in the tree was best estimated using a clinometer as estimates with a two-meter reference placed by the tree varied by 3–11 meters (Mean: 5.31 ± 2.44). We determined that the best support size estimates were those generated relative to the size of the focal animal and divided into broader categories. Support angles were best estimated in 5° increments and then checked using a Haglöf clinometer in combination with a laser pointer. We conclude that three major factors should be addressed when estimating support features: observer error (e.g., experience and distance from the target), support deformity, and how support size and angle influence the positional mode selected by a primate individual. individual. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.