Why is carrying capacity of Lesser Prairie Chicken populations declining across the southern Great Plains?

Background/Question/Methods  Stochastic growth models offer a powerful tool to evaluate long-term population dynamics of Lesser Prairie Chicken (Tympanuchus pallidicinctus) by integrating analysis of both density-dependent and density independent factors affecting annual rates of change into a single analysis capable of estimating carrying capacity while testing important hypotheses concerning a multitude of factors that potentially influence population dynamics. We evaluated the potential for 26 stochastic growth models to describe the observed dynamics of 4 Lesser Prairie Chicken populations attending leks across the species range from 1964 to 2016. Ongoing analyses incorporate potential factors influencing carrying capacity such as drought occurrence and severity, energy development and ongoing changes in farming practices and land cover characteristics.

Results/Conclusions  We identified the Gompertz model with declining carrying capacities (-1.8% to -9.6% per year) as statistically superior to the 25 alternative models. The best models imply substantially different probabilities of persistence for the 4 populations (100% to 70% in short-term, 15% to 0% in long-term) if observed patterns of population fluctuations and trend continue into the foreseeable future. We found that drought, Conservation Reserve Program (CRP) acreages and number of oil and gas wells are critical factors influencing annual rates of change for Lesser Prairie Chicken populations with potentially profound influence in the future due to ongoing climate change across the Southern Great Plains. Policy changes such as increased support for CRP conversions of agricultural commodity production to natural grasslands and reductions in new oil and gas drilling could ameliorate future declines in carrying capacity for this threatened species.