Adoption of ecological sites as monitoring and management units by a variety of land users has prompted discussion of their benefits for wildlife habitat management. Density and occurrence of shrub-steppe passerines are often related to key habitat characteristics such as plant species composition, cover, and structure. Until recently, ecological sites have not been tested as units for monitoring and management of passerines. We conducted a study implementing ecological sites as management units and used passerines as indicators of potential use of these sites. Ecological site characteristics and three sagebrush-obligate passerines were quantified on ecological sites at and near Browns Park National Wildlife Refuge in Colorado. In 2006 and 2007, we surveyed passerines and site characteristics using standard techniques within 101, 100-m radius plots. Density of Brewer’s sparrow (Spizella breweri) and occurrence of Brewer’s sparrow, sage sparrow (Amphispiza belli), and sage thrasher (Oreoscoptes montanu) were estimated for six ecological sites and then related to site characteristics. For example, Brewer’s sparrow densities were greatest (3.0 birds/ha) on a Loamy Fine Sand Ecological Site containing taller vegetation than vegetation for other ecological sites. Scientific literature commonly associates Brewer’s sparrows with sagebrush (Artemisia tridentata) presence, but on ecological sites at Browns Park Brewer’s densities are related more to vegetative structure rather than species composition. Results show there are links between passerine populations and ecological sites; a relationship which provides a meaningful foundation in developing long-term monitoring protocols and enhancing management decisions to favor sagebrush-obligate passerines.
Williams, Mary I.; Thurow, Thomas L.; Paige, Ginger B.; Hild, Ann L.; and Gerow, Kenneth G.
"Sagebrush-Obligate Passerine Response to Ecological Site Characteristics,"
Natural Resources and Environmental Issues:
Vol. 16, Article 10.
Available at: http://digitalcommons.usu.edu/nrei/vol16/iss1/10