Management and Conservation Spatially Explicit Modeling of Lesser Prairie-Chicken Lek Density in Texas JENNIFER M. TIMMER, 1,2 Department of Natural Resources Management, Texas Tech University, P.O. Box 42125, Lubbock, TX 79409, USA MATTHEW J. BUTLER, U.S. Fish and Wildlife Service, P.O. Box 1306, Albuquerque, NM 87103, USA WARREN B. BALLARD, † Department of Natural Resources Management, Texas Tech University, P.O. Box 42125, Lubbock, TX 79409, USA CLINT W. BOAL, U.S. Geological Survey, Texas Cooperative Fish and Wildlife Research Unit, Texas Tech University, Agricultural Sciences 218, Lubbock, TX 79409, USA HEATHER A. WHITLAW, 3 U.S. Fish and Wildlife Service, P.O. Box 42125, Lubbock, TX 79409, USA ABSTRACT As with many other grassland birds, lesser prairie-chickens (Tympanuchus pallidicinctus) have experienced population declines in the Southern Great Plains. Currently they are proposed for federal protection under the Endangered Species Act. In addition to a history of land-uses that have resulted in habitat loss, lesser prairie-chickens now face a new potential disturbance from energy development. We estimated lek density in the occupied lesser prairie-chicken range of Texas, USA, and modeled anthropogenic and vegetative landscape features associated with lek density. We used an aerial line-transect survey method to count lesser prairie-chicken leks in spring 2010 and 2011 and surveyed 208 randomly selected 51.84-km 2 blocks. We divided each survey block into 12.96-km 2 quadrats and summarized landscape variables within each quadrat. We then used hierarchical distance-sampling models to examine the relationship between lek density and anthropogenic and vegetative landscape features and predict how lek density may change in response to changes on the landscape, such as an increase in energy development. Our best models indicated lek density was related to percent grassland, region (i.e., the northeast or southwest region of the Texas Panhandle), total percentage of grassland and shrubland, paved road density, and active oil and gas well density. Predicted lek density peaked at 0.39 leks/12.96 km 2 (SE ¼ 0.09) and 2.05 leks/12.96 km 2 (SE ¼ 0.56) in the northeast and southwest region of the Texas Panhandle, respectively, which corresponds to approximately 88% and 44% grassland in the northeast and southwest region. Lek density increased with an increase in total percentage of grassland and shrubland and was greatest in areas with lower densities of paved roads and lower densities of active oil and gas wells. We used the 2 most competitive models to predict lek abundance and estimated 236 leks (CV ¼ 0.138, 95% CI ¼ 177–306 leks) for our sampling area. Our results suggest that managing landscapes to maintain a greater percentage of grassland and shrubland on the landscape with a greater ratio of grasses to shrubs in the northeast Panhandle should promote greater lek density. Furthermore, increases in paved road and active oil and gas well densities may reduce lek density. This information will be useful for future conservation planning efforts for land protection, policy decisions, and decision analyses. Ó 2013 The Wildlife Society. KEY WORDS aerial survey, energy development, grassland, hierarchical distance sampling, landscape characteristics, natural gas, oil, roads, shrubland, Tympanuchus pallidicinctus. The occupied range of lesser prairie-chickens (Tympanuchus pallidicinctus) has been reduced by >90%, a decline attributed to direct habitat loss from conversion of native grassland to cropland, livestock overgrazing, and invasion of woody plants, and indirect habitat loss from disturbance by energy development (Taylor and Guthery 1980, Applegate and Riley 1998, Hagen et al. 2004). As a result, the lesser prairie- chicken is currently proposed for protection as a threatened species under the Endangered Species Act (U.S. Fish and Wildlife Service [USFWS] 2012). Lesser prairie-chicken populations have faced steady declines during the past 100 years in Texas, USA (Jackson and DeArment 1963, Crawford and Bolen 1976, Sullivan et al. 2000), and Texas Parks and Wildlife Department (TPWD) estimated a minimum of 6,000 birds from mostly road-based surveys located in high quality lesser prairie-chicken habitat (Davis et al. 2008). Texas currently produces the most wind-generated electricity in the United States (i.e., 22% of the nation’s total; American Wind Energy Association 2012) and 5 Competitive Renewable Energy Zones (CREZ) were Received: 17 January 2013; Accepted: 1 October 2013 Published: 16 December 2013 1 E-mail: timmerj3@gmail.com 2 Present address: Colorado State University, 1499 Campus Delivery, Fort Collins, CO 80525, USA 3 Present address: United States Fish and Wildlife Service, 2609 Anderson Avenue, Manhattan, KS 66502, USA † Deceased. The Journal of Wildlife Management 78(1):142–152; 2014; DOI: 10.1002/jwmg.646 142 The Journal of Wildlife Management  78(1)