A non-linear spotlight line transect method for estimating white-tailed deer population densities

Pierce, Brian L.
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Accurate estimates of population density are a prerequisite for managing exploited white-tailed deer (Odocoileus virginianus) populations. Many state agencies rely upon density estimates obtained from spotlight strip transect surveys to regulate annual harvest Yet, density estimates from the standard spotlight strip transect method are known to be inaccurate in areas of dense vegetation, and alternatives such as the Hahn method, mark-recapture, or aerial strip transects are cost prohibitive for state wide surveys~ The line· transect method is an alternative which has been criticized for inaccuracy of distance estimates and the additional time required to collect perpendicular distance data. Results from a two year study of white-tailed deer in central Texas are presented to demonstrate the utility of a new spotlight line transect sampling method. The method generates accurate perpendicular distance data from non-linear transects using inexpensive GPS, GIS, and laser range finding equipment. The new spotlight line transect method is relatively fast (0.15 ± 0.05 hours/km SD), spatially accurate to within limits of the equipment used (15.2 ± 13.9 m SD), consistently obtains larger sample sizes per transect (> 50% ), and returns more information per sighting (count, composition, and spatial location) than traditional spotlight strip transect sampling method. Results indicate the new spotlight line transect method is less biased than the traditional spotlight strip transect method, more efficient in terms of cost per unit effort (hours/km), and yields spatial data (deer locations) applicable for monitoring habitat use without identification of individuals (Design 1, Thomas and Taylor 1990).
Wildlife populations, Mammal populations, Wildlife management, White-tailed deer
Pierce, B. L. (2000). <i>A non-linear spotlight line transect method for estimating white-tailed deer population densities</i> (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.