Masters Theses

Date of Award

6-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Michael R. Pelton

Committee Members

Ralph W. Dimmick, Boyd L. Dearden, Arthur C. Echternacht

Abstract

The relationship between population estimates and scent-station visitation rates of raccoons was studied on the Chuck Swan Wildlife Management Area in Tennessee. Field work was conducted from 30 July 1981 to 3 July 1983. In 8,000 trapnights, 248 raccoons were captured a total of 649 times. Capture success of raccoons was significantly different between months (P<.0001). Capture success was 9.1% in the first year of the study and 14.8% in the second, corresponding to increases in population estimates. An observed sex ratio of 121 males per 100 females did not differ significantly from 1:1 (P=.07). Juvenile raccoons comprised approximately 23% of the capture sample in both years. Fifteen cases of raccoon mortality were documented. Survival rates were lowest in spring and fall reflecting losses due to both emigration and mortality; this complicates assessment of mortality effects even when ancillary information is available. In 1982, breeding activity of adult raccoons peaked in April with most parturition occurring from mid-May to mid-June. Seasonal estimates of raccoon population size were calculated for 2 study areas on Chuck Swan. Population estimates in 1983 were 25% and 38% greater than in 1982 on the control and experimental areas, respectively. Both open and closed estimators indicated that the raccoon population on the control area was denser than that of the experimental area. The Jackknife estimator in the computer program CAPTURE provided summer estimates of 148 and 120 raccoons for the control and experimental areas, respectively, compared to Jolly-Seber estimates of 119 and 76. Jackknife estimates were robust and helped assess the negative bias in Jolly-Seber estimates. Eighteen scent-station surveys were completed over the 2-year study. Mean monthly visitation rate of raccoons for both areas combined was 5.25%. Visitation rates for both areas combined ranged from 7.5% in summer to 2.6% in winter. Visitation rates did not differ among lines (P=.07). Visitation rates by raccoons on the control and experimental areas did not differ between years (P=.12, P=.20, respectively) and among seasons (P=.27, P=.88, respectively). With the exception of minimum temperature, weather variables exhibited no effect on raccoon visitation rates. Raccoon visitation rates did not vary by overstory type (P=.21), the presence of forest overstory (P=.23), understory type (P=.93), topographic location (P=.34), and the distribution of water at scent-stations (P=.81). No significant relationship was found between population estimates and seasonal visitation rates (P=.78) or between capture success and visitation rates by raccoons (P=.44). Management applica-tions of the scent-station technique, as employed in this study, appear limited because low visitation rates precluded statistical detection of population fluctuations. If the scent-station method is further developed for use in mountain habitat, efforts should focus on increasing visitation rates by designing the technique more specifically for raccoons.

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