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Spacing behavior of snowshoe hares in relation to their population dynamics

University of British Columbia

The importance of spacing behavior on snowshoe hare population dynamics was studied in the Kluane Lake, Yukon area from May 1978 to July 1979. Two study sites, each consisting of a 9.29 ha live-trapping grid, were used to capture and tag animals. Numbers were increasing over the study with May breeding densities going from 8 in 1978 to 20 in 1979. The increase was a result of higher than average (12.25 young caught per female) natality rates. Yearly juvenile and adult survival rates were equal at 20%. A total of 116 hares were equipped with radio-transmitters during the study. These were monitored to determine home range locations and individual movements. Home ranges overlapped by at least 30% between and within sexes throughout the year. Home ranges averaged larger for males (4-8 ha) than females (3-5 ha). During periods of birth, females contracted the size of their home range but not significantly. 14 radio-tagged individuals dispersed during the study. They moved an average of 1045 m and were from all age and sex classes with the exception of adult males. To determine the importance of spacing behavior on breeding females' home ranges and movements I removed a small group of individuals from a much larger group of radio-tagged animals. The initial removal was done 10 days before the birth of the first litters and was then repeated 10 days before birth of the second litters. Home ranges were monitored before and after each removal and compared to a control area. Females did not increase their use of the removal area nor was it colonized by individuals from beyond the ring of radio-tagged animals. This suggests that breeding female densities were not limited by spacing behavior. Females did shift use of their home range after the removal by spending up to 30% more time on the removal side of their range. This suggests that females use their range in a manner that avoids interaction. Adult females were removed from one of the study areas during the late breeding season to assess their influence on juvenile movements and survival. There were no significant differences in these aspects between the manipulated area and a control. However, telemetry showed that juvenile and adult female home ranges overlapped little on the control area during September. The movements to create this situation were done by juveniles at a time before they could be trapped or radio-tagged. This suggests that some juveniles may leave their parents' home ranges at a time prior to which is detectable by conventional trapping and telemetry. The need for further investigation in this area is stressed.

Text

2010-03-24

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http://hdl.handle.net/2429/22467

Zoology

University of British Columbia

Graduate