Evaluation of Radio-Tracking by Triangulation with Special Reference to Deer Movements

Abstract

Four parameters out of the five investigated were found useful for studying white-tailed deer (Odocoileus virginianus) movements by triangulation with an automatic radio-tracking system. These were total area, greatest linear dimension, mean ac -tivity radius and distribution of activity radii, and appearance of the map. Random plots, which simulated deer movements, were used to determine the effects of varying the location of the animal''s range in relation to the triangulation stations. Results show an increase in size of range and a loss in accuracy of location as the plots were moved out. An "hour-glass-shaped" area of about 3300 acres is considered to be within acceptable accuracy with a 0.5-mile base line and a [plus or minus]0.5[degree] resolution. Point locations were obtained at 1-min intervals for selected time periods for 3 deer. These data were then sampled at intervals of 2, 3, 4, 5, 6, 10, 15, 30, and 60 min. Values for total area and greatest dimension decreased and the mean activity radius increased as the sampling interval became longer. A sufficient number of point locations can be maintained by using a short sampling interval or long observation period. Comparisons of home range size were made among individual deer and between a winter and an early spring period using the above 4 parameters. Spring ranges were significantly larger than winter ranges and movements in spring were longer with less concentration of activity. The differences between winter and spring behavior are probably related to higher spring temperatures and the disappearance of snow.