Effects of Two Sagebrush Control Methods on Nongame Birds

Abstract

Determination of breeding-bird densities 3-4 years after sagebrush (Artemisia spp.) control in central Utah revealed varied responses by bird species. Although total densities and species richness were similar among sites (81-109 territories/km2 of 4-6 species), the burned site contained 50-86% fewer Brewer's sparrow (Spizella breweri) territories than the chained and 17-year-old plowed sites. The vesper sparrow (Pooecetes gramineus) and western meadowlark (Sturnella neglecta), both grassland birds, were not noticeably affected by sagebrush control. Horned lark (Eremophila alpestris) densities were 1.8-2.8x greater on the recently treated sites. The sage thrasher (Oreoscoptes montanus) was only found in habitat patches containing the largest shrubs. Nesting requirements best explained the patterns of distribution and responses observed. Bird species diversity can be maximized by treating sagebrush areas in narrow (100 m) strips and maintaining blocks of mature sagebrush. J. WILDL. MANAGE. 46(4):945-952 Of over 350,000 km2 of lands in western North America dominated by sagebrush (Schroeder and Sturges 1975), at least 10% have been altered by mechanical, chemical, and biological techniques (Braun et al. 1976). Sagebrush control is conducted to increase forage production for livestock, make land available for cultivation, and extract mineral and energygenerating products. Although the effects of sagebrush alterations are well known for sage grouse (Centrocercus urophasianus) (Schneegas 1967, Carr and Glover 1970, Martin 1970, Wallestad 1975), few studies have been made of the effects on nongame birds. The short-term effects of herbicide treatment of sagebrush have been documented for Brewer's sparrow (Best 1972, Schroeder and Sturges 1975), vesper sparrow (Best 1972), and a bird community in Wyoming (Scott et al. 1966). Pyrah and Jorgensen (unpubl. rep., Montana Dep. Fish and Game, Fed. Aid Proj. W-105-R9, 1974) censused bird populations on the same sites Best (1972) used 5 years after treatm nt occurred. Responses of birds to sagebrush burning were studied by McGee (1976), and O'Meara et al. (1981) reported on nongame birds in chained pinyon-juniper (Pinus edulis-Juniperus osteosperma) habitats which are closely associated with sagebrush areas in the In-