Assessment of Radio Telemetry Error on Huntington Wildlife Forest, New York
Andy Stout
Background
Radio telemetry allows the observer to get insight on an animal's location without repeated direct contact with the animal. However, estimated locations may be affected by several sources of error. For instance, radio signals can bounce off mountainsides causing wavefront distortion (by signal refraction and scattering), which in turn gives the illusion that the signal is coming from a direction other than the correct direction from the receiver to the radio collared animal (Cochran 1980). Observer error has been assessed on Huntington Wildlife Forest (HWF) in the Adirondack Park, but a property wide analysis has not been done. The objectives of this study are to 1) assess telemetry error using beacons, and 2) develop a map showing the bearing error at each telemetry station on HWF.
Radio telemetry has been used at HWF to study white-tailed deer (Odocoileus virginianus) since 1972 (Tierson et al. 1985). Deer at HWF are captured using Stephenson box traps. Ear tags are placed on the deer for visual observation, physical measurements are recorded, and a radio collar is placed around the neck of the deer (Figure 1).
I analyzed telemetry stations using radio collars at known locations. From this data I calculated the average error, standard deviation, minimum and maximum bearing error (in degrees) for each station. The average and minimum bearing error were then mapped on an elevation map, with larger symbols indicating higher error (Figure 2 - click for full size image at 746 K).
I identified trends in telemetry error on some road sections with the available data from 1993 - 2002. The minimum bearing error values indicate that good telemetry is possible at 49 of 62 stations analyzed. A minimum bearing error over 10º is poor for a station that has had 5 or more bearings taken from the station. I identified 7 telemetry stations that are poor and 6 that are marginal due to topography, slope, signal bounce, and other factors. I was not able to distinguish which factors were the most important contributors to telemetry error on HWF. Therefore, this analysis should be performed with at least 20 bearings taken from each station.
Literature Cited
Cochran, W. W. 1980. Wildlife telemetry. Pages 507-520 in S. D. Schemnitz, ed. Wildlife Management Techniques Manual, 4th ed. The Wildlife Society, Washington, D. C. 686pp.
Tierson, W. C., G. F. Mattfeld, R. W. Sage Jr., and D. F. Behrend. 1985. Seasonal movements and home ranges of white-tailed deer in the Adirondacks. Journal of Wildlife Management 49(3):760-769.
Contact Information
Adirondack Ecological Center- aechwf@esf.edu
About The Author: Andy Stout is a senior dual major in Forestry and Environmental and Forest Biology at SUNY ESF who enjoys outdoor recreation of many kinds.