A device for monitoring radio-marked animals
A simplen portable, and economical recording system consisting of a receiver, signal conditioner, recorder, and power source is described. The system was designed to monitor the signal strength from a radio-marked animal at a particular location. Information is stored on recorder chart paper. Radio-marked ucks have been successfully monitored at nest sites, potholes, and other locations. Within the last 10 years, radiotelemetry as a technique to study wild animals has developed rapidly. Because most field telemetry projects are not designed to obtain data on a continuous basis, as described by Cochran et al. ( 19&5 ) and Cochran ( 1967), a large proportion of ffie available information is not collected. Our recording system was developed to monitor radiomarked animals at particular locations in field studies when ruggedness, portability, and cost of the recording system were of primary concern. Williams and Williams ( 1970) briefly described a recording system for monitoring ie presence and relative adivity of radio-marked bats. A recording device for monitoring the presence of radiomarked seals on ffie surface of sea ioe was mentioned by Siniff et al. ( 1969). Funds for development of the system were provided by the Northem Prairie Wildlife Research Center, Jamestown, North Dakota; by NIH Training Grant No. 5 TQ1 GMO177W04 from the National Institute of General Medical Sciences; and by the U.S. Atomic Energy Commission, COO-133b63. We acknowledge J. R. Tezster, L. M. Cowardin, and H. W. Miller for reviewing the manuscript and R. A. Reichle for preparing the drags MATERIALS AND METHODS The recording system, block-diagrammed in Fig. 1, consists of a receiver, signal conditioner, recorder, and power source. The receiver produees an audio output from an incoming signal. A signal conditioner converts the receiver output into a d-c current activating the recorder stylus. Stylus movement of a single channel d-c recorder (Model No. 288, recorder paper Style A, Rustrak Instrument Division, Gulton Industties Inc. Manchester7 New Hampshire ) is recorded on pressure-sensitive paper. The receiver is tuned aurally by using headphones to select the desired frequency and by obselrving the rearder to obtain the desired deflections of the stylus. Range of the system can be varied by adjusting the rf gain of the receiver or antenna gain. Selection of the type of antenna will depend on the relative positions of the antenna and the animal to be monitolred. If the antenna can be placed near ffie center of the area to be monitored, a nondirectional ntenna is the best choice. When the antenna must be 829 BRIEFER ARTICLES 830 Jot4rnal of Wildlife Manugement, Vol. 35i, No. 4, October 1971 | t v +12 VDC SUPPLY C l g 1 < GROUND 50 MFD 712K_ i < F TERMINAL ON
PORTABLE AUTOMATIC RADIOTELEMETRY RECORDING SYSTEM
Continuous, accurate, and automatic collection of wildlife telemetry data with little human attention is highly desirable, but has been difficult to obtain. Studies by Cochran and Lord (1963), Deat et al. (1980), Kolz et al. (1980), Schweinsburg and Lee (1982), and Lemnell et al. (1983) used automatic telemetry systems for obtaining location data. Other telemetry studies investigating presence or absence, activity, and physiology have used strip chart recorders (Gilmer et al. 1971, Moen 1978, Ward and Cupal 1979, Cederlund and Lemnell 1980, Folk and Folk 1980). Disadvantages of strip chart recorders have been discussed by Mech (1983) and Cederlund and Lemnell (1980). An optimum data-acquisition system would record data with precision and resolution and be inexpensive, lightweight, simple to operate, computer compatible, tolerant of exposure, and functional with minimal human attention. Free-roaming wild animals can be monitored automatically with radiotelemetry using portable, battery-powered microcomputers, and data collected can be transferred to a computer without manual transcription (Howey et al. 1984, Cooper and Charles-Dominique 1985). This paper describes 1 such system used to automatically collect radio-telemetered data, evaluates its accuracy, and presents possible applications of the data.
Radio Tracking of Homing Bats
Neotropical bats, Phyllostomas hastatus, were released 10 kilometers from their home roost, and their homeward flights were tracked by radio. Flights of bats with unimpeded vision were strongly oriented in the homeward direction, while the flights of blindfolded bats did not show this marked orientation.