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Population dynamics of eastern wild turkeys relocated into the post oak savannah of Texas
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Objectives of this study were to provide information on the status of eastern wild turkeys (meleagris gallopavo silvestris) relocated into the Post Oak Savannah of Texas. Specifically, I evaluated and discussed (1) survival and reproduction, (2) effects of yaupon (Ilex vomitoria) understory, (3) nesting habitat, and (4) other limiting factors of relocated wild turkeys. To achieve these objectives, relocated radio-tagged wild turkeys (n=82) were released into 4 areas in the winters of 1994-95. Mortality, reproduction, and habitat use were monitored using radiotelemetry. First-year annual survival for gobblers and hens averaged 29 and 48%, respectively. Male survival in this study was the lowest reported for this subspecies. Predation (63%) was the primary cause of mortality for relocated birds. High post-release mortality also was attributed to habitat unfamiliarity. Poult survival during the first-and second-year nesting season (2-weeks post-hatch) was zero. Reproductive success (i.e. population recruitment) was the lowest (O%) reported for this subspecies. Effects of yaupon understory on relocated turkeys were evaluated using color infrared photos taken during winter ("leaf off'). This allowed cover type (i.e.. forest and pasture) and yaupon understories (i.e. percent crown closure) to be delineated and inputted into a Geographical Information System (GIS). I found female turkeys avoided (P < 0.001) dense yaupon understories (> 31% crown closure). However, I found males neither avoided nor preferred forested habitats with dense yaupon understories (E = 0. 1 5 1), suggesting a differential habitat preference by sex. I found that most (8/11, 73%) females killed by mammalian predators were in forested habitats with open understories ([ ] 30% crown closure), conversely most (5/6, 83%) males were killed in forested habitats with dense understories. I suggest that dense cover allowed predators, such as bobcats (Felis rufus) and canids (Canis sp.), to stalk and ambush wild turkeys, which could explain high (71%) first-year male mortality observed in this study. I assessed nest-site selection of relocated wild turkeys. Comparisons were made between 22 nests of radio-tagged turkeys and 22 random sites. Measurements of variables were obtained to characterize understory and ground cover of turkey nests. Furthermore, physiographic variables also were measured, including Euclidean distance to transition zones ("edges") and presence/absence of protective barriers ("guard object"). Results indicate nest-site selection by wild turkeys was not random. Key nest-site characteristics identified were lateral cover (i.e. vegetation density) and height of vegetation. I evaluated 2 proposed factors that could account for high mortality and low poult success observed in this study: (1) spring precipitation and (2) predator numbers. I found spring precipitation during the 1994-95 nesting season was not above historic average (1950-93). Furthermore, predator numbers/100 km between northern (i.e. where established turkey populations exist) and southern (i.e. location of study areas) post oak savannahs were 63 and 34, respectively. These data suggest spring precipitation and predator numbers were not different in southern post oak during the years of my study. All 4 research sites failed. Furthermore, I suggest that (1) nesting/brood habitat, (2) stocking numbers, (3) capture and handling methods, and (4) radiotelemetry methods limited the survival and growth of turkey populations I studied in the southern post oak savannah.
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Includes bibliographical references: p. 48-53.
Issued also on microfiche from Lange Micrographics.
Lopez, Roel Roberto (1996). Population dynamics of eastern wild turkeys relocated into the post oak savannah of Texas. Master's thesis, Texas A&M University. Available electronically from
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