Influence of climate change and land use on Lesser Prairie-Chicken (Tympanuchus pallidicinctus) populations persistence in the Sand Sagebrush and Short-Grass Prairies
Godar, Alixandra J.
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Observed long-term, range wide declines in Lesser Prairie-Chicken (Tympanuchus pallidicinctus) numbers are primarily attributed with decreases in habitat quality and quantity in the Great Plains, with weather driving short term trends. The influence of land cover patterns and anthropogenic structures on lek attendance and the influence of weather on Lesser Prairie-Chicken vital rates remain unexplored in the Sand Sagebrush and Short-Grass Prairies in the northern extent of the species’ range. I assessed the influence of weather on survival rates by using the known-fate model and nest survival model in Program MARK to assess effect sizes of biologically relevant weather variables on adult survival and nest and brood survival, respectively, for each ecoregion. To assess the relationship between land cover and lek attendance, I used an anthropogenic dispersion index to evaluate the influence of structures within 4.8 km of the lek on lek attendance using a generalized linear model. Finally, I developed an integrated population model (IPM) to assess the effect of contemporary weather patterns on lambda (rate of population change), female survival, nest survival and chicks fledged to facilitate the development of forecasting long-term population trends, given climate change forecasts for the Great Plains. In my assessments of the influence of weather on survival rates, female survival in the Short-Grass Prairie was low (0.41, SE = 0.07; 95% CI = 0.29, 0.56) but small effect sizes indicate survival was not driven by weather. The nest survival model of hot days during incubation + cold days during incubation + total precipitation during incubation had the most support in the Short-Grass (AICC = 498.27, AICC wi = 0.99) and Sand Sagebrush ecoregions (AICC = 889.44, AICC wi = 0.99). My results of the influence of land use on lek persistence, suggest that lek attendance is affected by anthropogenic structure dispersion in the Sand Sagebrush Prairie Ecoregion but not in the Short-Grass Prairie Ecoregion. Significant parameters in the Sand Sagebrush Prairie Ecoregion include well dispersion (0.43, SE = 0.18; 95% CI = 0.06, 0.79) and transmission line dispersion (-1.93 SE = 0.22; 95% CI = -2.37, -1.49). In addition, there was a small negative effect of shrub patch size on lek attendance (-0.64, SE = 0.27; 95% CI = -1.17, -0.11) in the Sand Sagebrush Prairie Ecoregion while all confidence intervals overlapped zero in the Short-Grass Prairie Ecoregion. I speculate that responses varied due to the variation in landscape characteristics between ecoregions with the large tracts of grasslands in the Short-Grass Prairie Ecoregion and the highly developed Sand Sagebrush Prairie Ecoregion. The IPMs predicted either exponential growth (Short-Grass) or extinction (Sand Sagebrush). When weather projections varied from the current range of conditions, rates of change quickly became illogical in the Short-Grass Prairie. The IPM requires additional information to improve performance, either through additional parameters (Short-Grass) or increased sample size (Sand Sagebrush). My results suggest that weather is not the primary driver of vital rates and there is support for the influence of landscape metrics on Lesser Prairie-Chicken lek attendance in Sand Sagebrush Prairie Ecoregion, but not the Short-Grass Prairie Ecoregion. In the Sand Sagebrush Prairie Ecoregion IPM, landscape metrics should be incorporated while the Short-Grass Prairie Ecoregion requires additional research to determine which parameters should be incorporated into the model.