A Radio-Tracking System for Studying Movements of Deer

A six-transistor, superheterodyne, portable, directional receiver, utilizing a regenerative intermediate frequency detector at 5.0 megacycles, was designed and constructed to remotely monitor movements of deer (Odocoileus virginianus) marked with radio transmitters. Construction details and a circuit diagram of a new pulsing signal transmitter are given. Transmitters were slipped over the heads of two penned does and one fawn, and the movements of these deer, after release in the wild, were recorded for a 10-day test period in December, 1962, and again on February 5, 1963. During the test period, one doe moved about within an area slightly smaller than 1 square mile whereas the other two deer remained in the vicinity of the pen. This paper reports on tests of radio-tracking equipment made in December, 1962, and February, 1963, and on the movements of three penned white-tailed deer after they were released in the wild. We wish to thank the Minnesota Division of Game and Fish for the use of the facilities of the Carlos Avery Game Research Center and for providing the deer for release. Division biologists, B. A. Fashingbauer and J. M. Idstrom, assisted with the handling of the deer and provided valuable advice throughout the study. We also wish to acknowledge D. Raveling and D. Cline, graduate students of the University of Minnesota, who assisted in the field-tracking. Dr. W. H. Marshall critically read the manuscript and offered helpful suggestions. The investigation, supported by the Louis W. and Maud Hill Family Foundation, is part of a long-range ecological study of the motile responses of animals to certain physical and biological factors of the environment. One of the objectives of the project has been to solve ecological problems by using an interdisciplinary team approach combining the fields of biology and the physical sciences. The basic tracking system is similar to that described by Cochran and Lord (1963). Project personnel made modifications in the design of the transmitter, including the new pulsing circuit, and developed a transistorized tracking receiver weighing only 1.5 pounds. From the standpoint of the biology of white-tailed deer, it would have been desirable to capture and mark wild individuals. However, the release of pen-raised deer provides certain advantages in evaluating a radio-tracking system. For example, we could walk to within approximately 100 yards of these animals after they had been released into a natural habitat. This enabled us to determine the exact position of the radio-tagged animal in the field as a check on our remote determination of its location. In addition, we anticipated and found that these pen-raised deer remained in the vicinity of the research station where they had been held in captivity.