Effects of rangeland management on the site occupancy dynamics of prairie-chickens in a protected prairie preserve

We investigated the site occupancy dynamics of greater prairie-chickens at Konza Prairie Biological Station, a protected site in northeastern Kansas that is managed for ecological research. We surveyed the site during mid-Mar to mid-May, 1981-2008, and recorded detections of birds in a grid of 6.3?ha survey plots (n = 187 plots). We used multiseason occupancy models to estimate the probabilities of occupancy (psi) and detection (p), and tested whether land cover in woody vegetation, and land use with prescribed fire or grazing management influenced the dynamic processes of site colonization and local extinction. Probability of detection per site was consistently <1 and varied among years (p = 0.120.82). Site occupancy of prairie-chickens declined 40% over the study period from a high of psi=0.19 +/- 0.02 SE in 1981 to a low of 0.11 +/- 0.03 in 2008, despite protection from disturbance at leks and losses to harvest. We found that different sets of environmental factors impacted the probabilities of colonization and local extinction. Probability of colonization for an unoccupied site was negatively associated with the proportion of site occupied by woodland cover (beta=-1.25), and was lower for grazed sites (beta=-0.62). In contrast, probability of local extinction was affected by a weak interaction between grazing and average frequency of prescribed fire (beta = -1.01), but model-averaged slope coefficients were not statistically different than 0. To conserve prairie-chickens, we recommend prairies be managed with combinations of prescribed fire and grazing that maintain a heterogeneous mosaic of prairie habitats, while preventing woody encroachment. To assess biotic responses to land management practices, field sampling should be based on occupancy models or similar techniques that account for imperfect detection. (C) 2011 The Wildlife Society.