EFFECTS OF MICROHABITAT AND MICROCLIMATE SELECTION ON ADULT SURVIVORSHIP OF THE LESSER PRAIRIE-CHICKEN

Populations of the lesser prairie-chicken (Tympanuchus pallidicinctus), an endemic grouse of the south-central United States, have declined precipitously. This species occurs in short- and mixed-grass prairies with sandy soils. Apart from perennial grasses of short stature, prairie-chicken habitat is characterized by dryland shrubs of the sand shinnery community, particularly the shinnery oak (Quercus havardii) and sand sagebrush (Artemisia filifolia). We measured microhabitat and microclimate characteristics at bird-centered and random points at the southwestern (New Mexico) and northeastern (Oklahoma) edges of the species' range. We estimated survival by locating radio-tagged prairie-chickens (n = 544) from April 1999 to June 2003. We found that lesser prairie-chickens used sites within the sand shinnery community that had a higher cover and greater density of shrubs (ANOVA: P < 0.0001). Microclimate differed substantially between occupied and random sites (MANOVA: P < 0.0001), and prairie-chicken survival was higher in microhabitat that was cooler, more humid, and less exposed to the wind. Survivorship was higher for adults that chose microhabitat with a higher cover of shrubs and grasses and a higher density of vegetation. Survivorship was higher for prairie-chickens that used sites with >20% cover of shrubs than for those choosing 10–20% cover; in turn, survivorship was higher for prairie-chickens choosing 10–20% cover than for those choosing