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Springer, J. T. 1976. A preliminary radio-tracking study of coyotes in south central Washington. Thesis, Department of Zoology, Washington State Universty, Pullman, Washington. 56 pp.
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ABSTRACT
This study was done to test radio-tracking equipment and establish its limitations on the United States Energy Research and Development Administration Hanford Reservation, in south-central Washington. Typical vegetation is sagebrush and grasses, growing in sandy, alluvial soil, deposited by the glacial Lake Missoula floods.
Radio equipment was tuned to the frequency of 151 MHz, which permitted the use of several high gain yagi antennas of easily handled size. Two receivers were used: a modified Heath Kit citizen’s band radio, and a Davtron Model LTS, both of which received six transmitter channels. The six transmitters were constructed at the Cedar Creek Natural History Area, Minnesota. They were potted in dental acrylic formed into a hard plastic collar.
Range and accuracy of the equipment were tested. The hand-held 3-element yagi antenna, used to track coyotes, had a range of 2.4 km. The truck-mounted 8-element antenna had a range of 4.0 km, and the 11-element antennas had ranges varying from 6.4 km to over 11.3 km, depending on their elevation above the surrounding terrain. When direction of the transmitter signal was determined by listening for the strongest signal, the standard deviation was 3.3 degrees at a distance of 1.6 km, and it was 2.7 degrees at a distance of 6.9 km. When the direction of the transmitter signal was determined by averaging the nulls on either side of the strongest signal, the standard deviation was 10.7 degrees at 1.6 km, 4.1 degrees at 2.4 km, and it approached 1.0 degree when the distance was 3.2 km or greater. The number of elements on the antenna affected the range of the equipment — more elements provided greater range — but had no apparent effect on accuracy. The higher the antenna was placed above the surrounding terrain, the greater its range, and its error was likely to be less. The Davtron receiver had a range about 1.5 times greater than the Heath Kit receiver. Obstructions such as sand dunes and rock outcroppings directly between the transmitter and receiver decreased range. Obstructions surrounding but not between the transmitter and receiver caused signal reflections, which increased error. Obstructions to either side of the line between the transmitter and receiver absorbed the signal to that side and increased error. High relative humidity decreased range. Presence of power lines only affected range and accuracy on humid days when static interference increased.
Four coyotes were caught and fitted with radio-collars. Two coyotes were located often enough to determine home ranges. Effects of error polygons on determining home range size is discussed. Coyote #1 had a home range of 1.66 km2 ± 0.44 km2. Coyote #5 spent over one month on an island in the Columbia River, with an area of 1.94 km2. He then moved 19.3 km south-southeast, and established a home range of 1.76 km2 ± 0.44 km2. These ranges are considerably smaller than those reported by other studies.
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