Nesting Success of Grassland Birds in Shinnery Oak Communities Treated with Tebuthiuron and Grazing in Eastern New Mexico

Abstract

Abstract Sand shinnery oak (Quercus havardii) communities, a major component of grassland habitat of birds in eastern New Mexico, frequently are managed with livestock grazing and herbicide application for control of shrubs. We examined nest density, nest-site selection, and daily rate of survival of nests of grassland birds among four combinations of treatments with tebuthiuron (0.75 kg/ha) and a short-duration, rotational-grazing system being used to restore sand shinnery oak communities in eastern New Mexico. During breeding seasons 2004 and 2005, we searched 4-ha subplots in four tebuthiuron-grazing-combination replicates for nests, measured vertical and overhead cover at each nest site and an associated random point, and estimated daily rate of survival of nests using program MARK. Density of nests was similar among all treatments but greater in 2005 than 2004. Although vertical cover differed among treatments and between years, it did not affect selection or success of nest sites. Overhead cover als...