Date of Award:
Doctor of Philosophy (PhD)
Department name when degree awarded
Frederick F. Knowlton
The study was conducted to examine the effect of exploitation on population parameters of coyotes (Canis latrans). Hypotheses tested were: (1) Substantial levels of exploitation do not change spring and fall coyote densities significantly; (2) Coyote recruitment (reproduction and immigration) rates are unaffected by substantial levels of exploitation; (3) Annual coyote survival rates are not related to intensity of harvest rates; (4) Coyote emigration rates remain unchanged by substantial levels of exploitation. Coyote demographic parameters were measured from 1975 to 1978 for a treatment population subject to substantial exploitation (Curlew Valley, Utah and Idaho), and for an unexploited to lightly exploited control population (Idaho National Engineering Laboratory, INEL). Treatment and control populations were about 100 km apart on environmentally similar areas. Availability and utilization of prey also were similar for the two populations, with the major difference being in the type of lagomorph consumed.
Relative spring densities, estimated by scent station indices, increased for both populations over the study period. Relative fall densities in the two areas were estimated by scent station lines, scat indices, and catch-effort indices and increased from 1975 to 1976, but were relatively constant thereafter. Estimates of absolute fall density from isotope labeling of feces also were similar within each area for 1977 and 1978. Neither spring nor fall density estimates were significantly different between areas in any given year or overall.
Recruitment rates, as estimated from spring to fall increase in scent station visitation rates generally decreased over the study period, while estimates from age and sex structure of coyotes trapped in the fall increased for both populations over the study period. Estimated recruitment to fall populations (Pf) was consistently greater in Curlew Valley each of the four years, and overall was significantly greater than recruitment at the INEL. Spring to fall change in scent station indices was greater for Curlew Valley for all years except 1975.
Annual survival rates were estimated for adults and juveniles marked with transmitters and/or ear tags using methods of statistical inference from band recovery data. Estimated survival rates for adults and juveniles were constant over the study period for each population and did not differ significantly between populations. Estimates of adult and juvenile survival and/or recovery (mortality) rates were significantly different within the Curlew Valley and INEL populations.
Estimated hunting mortality rates for adults and juveniles remaining in the treatment population were 56 and 350 percent higher than similar estimates for the control population. Significantly higher in situ juvenile hunting mortality rates were associated with significantly lower nonhunting mortality and emigration rates. Emigration was not only greater from the control population, but it was distributed more evenly over the fall and winter.
The following conclusions resulted from the study. Exploitation (kill) rates were substantially higher in the treatment population as expected. Observed differences in fall-winter adult and juvenile in situ kill rates did not produce significant differences in spring or fall densities, or in annual survival rates. Recruitment rates were related directly to hunting mortality rates, while emigration rates were related inversely.
Davison, Robert P., "The Effect of Exploitation on Some Parameters of Coyote Populations" (1980). All Graduate Theses and Dissertations. 6990.
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