POPULATION ECOLOGY OF THE EASTERN WILD TURKEY IN NORTHERN MISSOURI

The success of eastern wild turkey (Meleagris gallopavo silvestris) re storation programs in the Midwest has led to dramatic increases in occ upied range. Habitats with limited forest land, once thought unsuitabl e for wild turkey, now support densities that exceed 30 birds/km(2) of timber. Turkey population growth has resulted in the liberalization o f harvest regulations with corresponding increases in hunter numbers a nd turkey harvest. As pressures on the wild turkey resource escalate, so does the need for an enhanced understanding of population dynamics. We used radiotelemetry to investigate survival and reproduction of wi ld turkey hens from 1980 to 1989 in the mixed timber-agricultural regi on of north-central Missouri. We also used direct recovery rates of ba nded gobblers to examine spring harvest mortality. Radio-marked hens ( n = 327) were monitored annually, greater than or equal to 5 times/wee k, to derive estimates of cause-specific mortality, seasonal survival, and reproductive parameters. Band numbers from tagged gobblers (n = 1 34) were recorded at mandatory turkey check stations to estimate harve st mortality. Seasonal survival rates of hens were variable, with wint er rates exhibiting the greatest range (0.625-1.00). Although daily su rvival rates did not differ among seasons (P = 0.142) according to ana lysis of variance, a model selection procedure indicated that seasons could not be combined. Cause-specific mortality varied among seasons w ithin years, with predation being the major cause of mortality. Legal fall-harvest mortality averaged 4.4% of radio-marked hens. Illegal kil l of hens during the spring gobbler season ranged from 0.0 to 30.0% an d averaged 5.2%, exceeding legal fall harvest of hens in some years. D uring the first year after banding, 11.2% of adult gobblers were harve sted during spring hunting season. The nesting rate (measured as the p roportion of hens attempting to nest) was consistent and high (greater than or equal to 0.9) across years; however, hen success and nest suc cess showed significant annual variation. Hen success differed between adult and subadult hens as did the success of first nests. We observe d no difference in the success of renests between age classes of hens. Most poult mortality occurred by 2-weeks posthatch; however, annual e stimates varied among years. Poult mortality at 4-weeks posthatch rang ed from 0.419 to 0.705. Across years, increasing poult mortality was a ssociated (p = 0.75, P = 0.054) with the number of days in June that r ainfall exceeded 2.54 cm. We used a stochastic population model to exa mine the effects of simulated spring harvest on the age structure of m ales and the effects of fall harvest on population growth. Increasing levels of spring harvest resulted in a decreasing proportion of adult males in the spring population and in the harvest. At a 5% level of fa ll harvest, population size at year 40 increased in 72% of the simulat ions. When a 10% level of fall harvest was modeled, population size at year 40 decreased in all simulations. The model was sensitive to chan ges in hen survival, nest success, and poult mortality. Simulations we re run for 40 years with an initial population size of 5,820. Decrease s in poult mortality of 10 and 20% resulted in increases in average si mulated population size at year 40 of 3,154 and 19,957% (32.54 and 200 .57 fold), respectively. The variation we observed in wild turkey surv ival and reproduction and our population model outputs suggest that ha rvest strategies can affect population growth and age structure. Fall harvests have the greatest potential to affect population growth. We r ecommend that state-level estimates of harvest, hunting pressure, repr oduction, and survival form the basis for developing and evaluating wi ld turkey harvest strategies in the Midwest. A conservative approach t o spring and fall harvest regulations is recommended if sufficient dat a to model populations are not available.