John H. Brunjes, IV
Ph.D., Texas Tech University, 2005
My name is John Brunjes and I recently completed my Ph.D. in Wildlife Science in the Department of Range, Wildlife, and Fisheries Management at Texas Tech University. My major professors were Dr. Mark Wallace and Dr. Warren Ballard. I am currently looking at Rio Grande wild turkey hatchling sex-ratios by DNA analysis of egg shell membranes. My dissertation research was on the Rio Grande subspecies of the wild turkey. I created a population model and examined landscape scale habitat selection. I plan to link the population model to the landscape data in order to provide better information on how landscape features affect population performance. This project is one of the largest scale studies ever undertaken on Rio Grande wild turkeys. Many other graduate students here at Texas Tech University will also be working on this project. They will be looking at many aspects of the natural history and ecology of Rio Grande Wild Turkeys.
Concerns began to arise over populations of Rio Grande wild turkeys (Meleagris gallopavo intermedia) in the low rolling plains of the Texas Panhandle. After successful increases in the populations of turkeys in the Texas panhandle, this population began to decline again in the early 1970’s. The declines were evidenced by reduced hen-poult counts and fewer and smaller winter roost sites. Roosts that had once had >500 turkeys now have only 100-200 birds. Other roosts have vanished all together. Concerns over the future of Rio Grande wild turkeys in this region prompted this study. While the wild turkey has been extensively studied, little information existed on Rio Grande wild turkeys in this portion of their range. The causes of these declines are a mystery. Hypotheses about the causes of these declines include; increasing predator densities, loss of riparian forests, and changing land-use practices. We initiated a long term study into the ecology of Rio Grande wild Turkeys at 3 Study sites in the Texas Panhandle and 1 study site in Southwestern Kansas. Information provided by this study will give us better insight into the ecology and habitat requirements of the Rio Grande wild turkey.
Previous studies of habitat use by Rio Grande wild turkeys in northern portions of their native range have been limited, and those have focused on 1 spatial scale at 1 study area. We initiated a large scale project at multiple study areas to better understand how Rio Grande wild turkeys use available habitats. In 2000-2002, we captured and followed the movements of Rio Grande wild turkeys at 3 sites in the Texas Panhandle and 1 site in southwestern Kansas (2000-2001). We recorded 25,837 locations (n=17,087 for females, 8,750 for males) of Rio Grande wild turkeys across all study sites. We calculated 50% Core use areas for 195 female and 118 male turkeys. Both sexes used vegetation types in different proportions than was available on the landscape. Selection of vegetation types was fairly consistent between the regional and local scale but in some cases we did observe differences. Males and females selected Woodlands (P < 0.05) at both the regional and local scales, while Agriculture was avoided at both the regional and local scales. We observed mixed results when comparing between or among scales within the other vegetation classes. These differences were primarily due to differences in vegetation composition and subclass component availability at individual sites. Turkey use of Woodland vegetation types across scales highlights the importance of Woodlands for birds in the region.
Rio Grande turkeys in the Texas panhandle and southwest Kansas are believed to have experienced population declines in recent years. Beginning in January 2000, we initiated a long-term study to determine population dynamics of Rio Grande turkeys at 3 study sites in the Panhandle region and 1 in southwestern Kansas. We radio-transmittered 667 turkeys that we used to estimate survival rates for birds in the region. Transmittered female turkeys were also used to estimate reproductive success for each study area, and poults were transmittered to estimate their survival. A stochastic stage-structured population model was created using MATLAB®. The model was based on the Lefkovitch matrix and used adult, sub-adult, preflight and post-flight poult, and nest stages to predict population outcome. Survival and reproductive data for turkeys at each study site were input into the model to predict population trends at each site. In the Texas Panhandle, populations were stable to slightly increasing (λ = 1.024 ± 0.007). We found the population at 1 site to be increasing (λ = 1.17 ± 0.014), 1 site to be approximately stable (λ = 1.012 0.013), and 2 sites to be declining (λ = 0.81 0.011) and (λ = 0.86 0.042). Based on elasticity analyses, populations were most sensitive to changes in recruitment rates and autumn survival. Mortality due to current legal and illegal harvest levels had little impact on predicted population outcome.
Researchers investigating survival of wild turkeys traditionally have assumed mortalities within the first 14 days may be capture related, and have excluded those data from analyses. Few have explored ways to reduce mortality during this period. In 2000, we initiated a long-term radio telemetry study of the ecology of Rio Grande wild turkeys in the southern Great Plains. During 2000-2002, we captured and outfitted 667 turkeys with backpack-style radio transmitters. We recaptured 123 previously transmittered birds for a total of 790 14-day survival periods. Sixty-seven birds (8.5%) died <14 days post capture and were considered capture-related mortalities. Male mortality (13.4%) was greater than female (5.8%) mortality (P = 0.001). Birds captured in the afternoon had higher (P = 0.035) mortality rates (11.6%) versus morning (8.0%) or mid-day (7.1%) captures. We found no differences in mortality among study sites (P = 0.14), years (P = 0.27), age class for males (P = 0.38) or females (P = 0.99), or capture method (P = 0.64). We found no relationship between weather conditions and 14-day postcapture survival of turkeys with the exception of precipitation 48 hours post capture (P = 0.01). We recommend minimizing handling of males and avoiding afternoon captures to reduce capture-related mortalities.
This page maintained by
Matthew
J. Butler
This page created by
Matthew J.
Butler
last updated
11/06/06