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
Radio tracking of homing and feeding flights of a neotropical bat
Summary 1. Flights of the bat Phyllostomus hastatus released at distances of 20, 30 and 60 km from the home roost were followed by radio tracking. Flights from 20 km were accurately directed homeward, those from 30 km less so, and bats released at 60 km wandered in all directions. 2. Radio tracking was also used to study the movements of bats near their home roosts in search of food. The bats regularly made rapid, well-oriented flights to and from their feeding areas. No two bats followed the same route during these flights. 3. The same visual orientational systems which allow these bats to return rapidly during homing experiments may also facilitate flights to and from feeding areas and aid in the search for new sources of food.
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.