Introduction of the Wild Turkey North of its Original Range into Northern Wisconsin
Acker, J. Randolph
University of Wisconsin-Stevens Point, College of Natural Resources
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This study was undertaken to describe home range, habitat use, mortality factors, and reproductve success of eastern wild turkeys (Meleagris gallopavo silvestris) introduced north of their original range into northern Wisconsin. During winter 1977 and winter 1978, 81 wild turkeys were trapped in Roscommon County, Michigan and released in the southern end of the Nicolet National Forest. Twenty hens ( 5 in 1977 and 15 in 1978) were radio-tagged; 1488 radio locations were recorded. Home ranges were determined for monthly and seasonal periods using Minimum Area and Modified Minimum Area Methods. Habitat use was determined by plotting locations on timber-type maps and calculating importance value ranks for each habitat type. Data were analyzed for monthly periods; separate analyses were conducted for each release site and age class. Home range size and habitat use showed monthly and seasonal changes that were affected primarily by weather, reproductive behavior, and distribution of food resources. When snow depth was greatest, during February, home ranges averaged 6.3 ha for adults and 8.3 ha for juveniles and were the smallest observed during the study. Oak (Quercus spp.), aspen (Populus spp.) and conifer stands were used extensively, but only conifers were characteristic of all wintering areas. Settled snow in conifer stands allowed turkeys to move on the ground, and was the major factor affecting habitat selection. March and April home ranges increased substantially as a result of moderating winter conditions and spring dispersal. Average April home ranges of adults were 20 times larger than during February, and those of juveniles were over 40 times larger. Adult hens at 1 release area showed increasing use of oak and open habitat, whereas a single surviving adult at a second release area used aspen and northern hardwood habitats. Juveniles continued to use oak, aspen, and conifer habitats. All radio-tagged hens nested during May and showed great variation in selection of nesting habitat. During June and July, adult hens with broods increased their home ranges (June 61.5 ha, July 144.7 ha) probably reflecting growth and increased mobility of young. Aspen was most commonly used in June. Two adults with broods shifted to almost exclusive use of open habitat during July while a third adult with a brood continued to use aspen. Juvenile hens, none of which nested successfully, had an average home range size of 134.5 ha during June. Their home range decreased in July to 104.4 ha. During these months juveniles used aspen, northern hardwood, lowland hardwood, and oak. Home range size decreased sharply during August with adults covering an average of 20.1 ha and juveniles using 72.0 ha. Habitat use was similar to that of July for both age classes. Starvation was the most important mortality factor. During 1978 (an average winter) it accounted for a minimum mortality of 57% for radio-tagged adult hens and 50% for radio-tagged juvenile hens. All radio-tagged hens which survived the winter nested. Adult hatching success ranged from 66 to 100% while that of juveniles was 0%. Poult survival at age 6 weeks or older ranged from 50 to 75%· Extrapolation of 1978 telemetry data to the entire introduced female population indicates that there were 35 females in the study area as of August 1978, 4 less than were introduced during winter of the same year.