WINTERING HABITAT ASSOCIATIONS OF A DECLINING GRASSLAND BIRD, THE SPRAGUE'S PIPIT (ANTHUS SPRAGUEII)

摘要

The Sprague's pipit (Anthus spragueii) is a passerine of North American prairies, breeding in the northern United States and southern Canada, and overwintering in the grasslands and deserts of the southern United States and northern Mexico. In recentdecades, pipit populations have declined in both breeding and wintering ranges because of degradation and loss of native prairie. Previous research on this species has focused primarily on its breeding habitat and provided limited information on its wintering habitat. To help fill in these data gaps, we assessed wintering density along the Texas Gulf Coast Plain, as well as characteristics of the associated habitat. We used a distance-based line-transect sampling technique to estimate pipit densities during the winters of 2013-2014 and 2014—2015 at seven conservation sites and found Sprague's pipits at all sites. The highest number of detections and the highest density estimates were at the Attwater Prairie Chicken National Wildlife Refuge. Habitat associated with pipits included open grasslands with mixed forbs and low vertical cover. Although wildlife biologists consider pipits to be native grassland specialists in their breeding range, our analyses did not identify proportion of native grasses asan important variable. Instead, the physical structure of the vegetation (short and sparse grass cover) was most important to pipit presence. Our results suggest that habitat management to benefit wintering populations of this species should focus on vegetation structure, though native grassland cover might be important at a larger scale.