Summer Movements and Habitat Use by Sage Grouse Broods in Central Montana

Abstract

The habitat use and movements of sage grouse (Centrocercus urophasianus) broods were studied with the aid of radiotelemetry in central Montana during the summers of 1968 and 19619. Five hundred and eleven locations were obtained on 13 radio-marked sage grouse broods. In both summers big sagebrush (Artemsa trixlentrata) in scattered (1-10 percent) and common (10-25 percent) densities received the greatest utilization by broods. Sagebrush heights at brood sites ranged mainly between 6 and 18 inches. For the 2 years combined, sagebrush canopy coverage averaged 14 percent for June, 12 percent for July, 10 percent for August, and 21 percent for September. Broods utilized sagebrush-grassland benches early in the summer (June and July) and shifted to greasewood (Sarcobatus vermicalatus) bottoms and/or alfalfa (Medicago sativa) fields as the forbs on the higher elevations became desiccated. Broods remained in these bottom types until late August and early September and then shifted back into sagebrush. Sizes of areas used by broods averaged 213 acres in sagebrush in early summer (June and July), 144 acres in alfalfa fields (July and August), 91 acres in greasewood bottoms (July and August), and 128 acres in sagebrush in late summer (August and September). Availability of food appeared to be the factor that determined the vegetational types utilized by broods during different periods of the summer. Manipulation of sagebrush to increase grass as livestock forage has been the goal of many western range managers in recent years. In 1965, the Montana Fish and Game Department, in cooperation with ffie United States Department of the Interior, Bureau of Land Management, initiated a 10-year study to determine the ecological effects of sagebrush removal. As part of this project, I studied the habitat use and movements of sage grouse broods wiffi the aid of radiotelemetry during the summers of 1968 and 1969. The study was conducted in central Montana on a nonmigratory population of sage grouse (Eng and Schladweiler 1967). Previous studies of brood habitat of sage grouse have shown heavy use of sagebrush types early in summer, with midsummer movement to more mesic sites, such as 1A joint contribution from the Department of Zoology and Entomology, Montana State University, Bozeman, and the Game Management Division, Federal Aid Projects W-105-R-3, 4, 5, Montana Fish and Game Department. Published as a Journal Series No. 159, Montana Agricultural Experiment Station. creek bottoms and mountain meadows (Batterson and Morse 1948, Patterson l9S2, Dalke et al. 1963, Klebenow 1969, and Peterson 1970). The above-mentioned studies were based on observations of broods occurring along brood routes. The present study is based on movements of individual radio-equipped broods. I wish to extend sincere appreciation to R. L. Eng, Montana State University, for field assistance, technical supervision, and guidance in manuscript preparation; R. Greene, Montana Fish and Game Department, for field assistance; and T. W. Mussehl, E. F. Schlatterer, D. Pyrah, and P. Schladweiler, all with the Montana Fish and Game Department, for advice and assistance in various phases of the study.