Factors Affecting Ruffed Grouse Drumming Counts in Southwestern Wisconsin

Abstract

The effects of steep topography and land use on ruffed grouse (Bonasa umbellus) drumming counts were studied in southwestern Wisconsin. Topography created substantial differences in audibility of the drumming between locations. Drumming counts were unusually low in spring 1976, but increased by 2.7 tihles in 1977. Numbers of territorial males increased by only 29%. This disparity was due to greater drumming participation by territorial males in 1977. The relationship of drumming frequency with numbers of drumming grouse was more positive (P < 0.001) in southwestern than in northern Wisconsin. Topographically induced competition may account for this regional difference. Recommendations concerning how and when to conduct drumming counts are discussed. J. WILDL. MANAGE. 45(2):409-418 Wildlife biologists constantly seek to improve the accuracy, precision, and efficiency of population monitoring techniques. This was the purpose of studies by Petraborg et al. (1953) and Hungerford (1953) when they developed the drumming count as a means of censusing populations of ruffed grouse in spring. Drumming counts are no longer used as a direct census. However, they are widely used as an index to regional trends in ruffed grouse breeding populations and are used to help forecast fall harvests. Since its development, the roadside drumming count has been tested for use in northern Wisconsin (Dorney et al. 1958). In 1963, the Wisconsin Department of Natural Resources (WDNR) extended the use of these counts to ruffed grouse range in the southwestern portion of the state, but did not evaluate the drumming-count method there. This area differs in topography and land use from the areas studied by Petraborg et al. (1953) and Dorney et al. (1958). My study examined effects that topography and land use in southwestern Wisconsin may exert on ruffed grouse drumming indices. I thank R. A. McCabe and D. H. Rusch for th ir advice and assistance throughout the project. J. B. Hale and A. J. Rusch of the WDNR provided drumming-count data collected throughout Wisconsin. J. G. Bollinger and A. Soom provided advice and equipment for the audibility experiments. S. R. Craven reviewed the manuscript. My special thanks are extended to R. Rinke and those students who assisted me, and to the landowners who permitted access to their property. TRANSECTS AND STUDY AREAS The study was conducted in northeastern Iowa County, approximately 50 km west of Madison. The unglaciated Driftless Area, as this region is known, is typified by dendritic drainage patterns and steep slopes. It also extends into northeastern Iowa and southeastern Minnesota. Nearly all of the area is in small, privately owned farms. Roads generally follow creek bottoms or the tops of some of the larger ridges. Most level and gently sloping areas have been cleared for crops or pasture. The woodlands are dominated by oaks (Quercus spp.), and closely resemble the southern xeric forests described by Curtis (1959). ' Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison; the Wisconsin Department of Natural Resources; and the U.S. Fish and Wildlife Service. 2 Present address: Kansas Fish and Game Commission, Hays, KS 67601. J. Wildl. Manage. 45(2):1981 409 This content downloaded from 207.46.13.120 on Wed, 14 Sep 2016 05:03:10 UTC All use subject to http://about.jstor.org/terms 410 RUFFED GROUSE DRUMMING COUNTS* Rodgers Two transects were established along a 25-km route that, except for 2 km, followed valley bottoms. Each transect consisted of 15 permanently marked listening stations at approximately 1.6-km intervals. Transect A has been run 1 or more times by WDNR personnel in all but 3 springs since 1950. This was the 1st drumming transect in southwestern Wisconsin, and provided a useful history of drumming in this area. Transect B was established, with stations approximately halfway between those of transect A, to examine the need for permanent stations in hilly terrain. Five stations and their surrounding areas (Fig. 1) were selected to allow comparison of drums heard with actual numbers of drummers available to be heard. These stations represented a range in drumming activity from consistently below to well above average. Cumulatively, the 5 areas totaled 889 ha, of which 589 ha were forested. Maximum relief was