Relationship of lesser prairie-chicken density to landscape characteristics in Texas

Date

2012-05

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

Ground-based lek surveys have traditionally been used to index trends in prairie grouse populations (Centrocercus and Tympanuchus spp.). However, indices of abundance or density can be fundamentally flawed and techniques that account for incomplete detection should be used. Distance sampling is a common technique used to estimate the density and abundance of animal populations and has been used with aerial surveys to monitor avian populations. With an increase in renewable energy development in native prairies and sagebrush steppe, there is a greater need to effectively monitor prairie grouse populations. One such species, the lesser prairie-chicken (LPC; T. pallidicinctus), has faced significant population declines and is thus, a species of conservation concern. In addition, much of the current and proposed wind energy development in the Great Plains overlaps some of the extant LPC distribution and few peer-reviewed studies have been conducted to investigate this potential threat to LPCs. Hierarchical distance sampling models can relate LPC lek density to landscape features and help predict the potential impact from wind and other energy development on lek density. Thus, the main objectives of our study were to estimate lek density in the LPC range in Texas and model anthropogenic and landscape features associated with lek density. We accomplished this by flying helicopter lek surveys for 2 field seasons and employing a line-transect method developed at Texas Tech University. We inventoried 208, 7.2 km × 7.2 km survey blocks and detected 71 new leks, 25 known leks, and observed 5 detections outside the current LPC range. We estimated 2.0 leks/100 km2 (90% CI = 1.5–2.8 leks/100 km2) and 12.3 LPCs/100 km2 (90% CI = 8.5– 17.9 LPCs/100 km2) for our sampling frame. Our state-wide abundance estimates were Texas Tech University, Jennifer M. Timmer, May 2012 vii 301.9 leks (90% CI = 219.4–415.4 leks) and 1,822.4 LPCs (90% CI = 1,253.7–2,649.1 LPCs). Our best model indicated lek size and lek type (wi = 0.360) influenced lek detectability. Lek detectability was greater for larger leks and natural leks rather than man-made leks. We used hierarchical distance sampling to build spatially-explicit models of lek density and landscape features. The 2 most competitive models included percent shrubland + transmission line (>69kv) density and only percent shrubland (AIC= 943.817, wi = 0.486; AIC = 945.098, wi = 0.256, respectively). We model-averaged our most competitive models and estimated the number of leks in our sampling frame at 245.7 leks (cv = 0.137). Lek density peaked at lower levels of transmission line density and where ≈60% of the landscape was composed of shrubland patches (shrubs <5 m tall comprising ≥20% of the total vegetation). Our state-wide survey efforts provide wildlife managers and biologists with population estimates, new lek locations, and identified spatially-explicit predictions of lek density. Our spatially-explicit models predicted lek density based on percent shrubland and transmission line density, which can be used to predict how lek density may change in response to transmission line development and changes in habitat conditions.

This copy has been corrected.

Description

Citation