Ruffed Grouse Drumming Site Counts

Abstract

Ruffed grouse (Bonasa umbellus L.) drumming site counts were initiated in the spring of 1941 on the Litchfield-Morris Wildlife Sanctuary in west-central Connecticut. The work has been continued with intensive surveys being made in 1941 and 1946, partial surveys in 1942 and 1943, and incidental surveys in 1944 and 1945.1 These drumming site counts were made on a 760 acre study area which is fairly representative of the New England Upland cover types that occupy most of the western half of the State of Connecticut. Much of the area was formerly cultivated and has reverted, either artifically or naturally to forest growth. Of the timber types present, hardwoods (mainly the oak ridge type) occupy 47 per cent of the area; swamp hardwoods, 22 per cent; coniferous plantations, 17 per cent; and miscellaneous types, 14 per cent. Many of the stands are wholly, or partially bounded by old stone walls, relics of the days of cultivation. The area is used to a minor degree for recreation, and a small forestry operation is carried on each year. The study area was divided into 40-acre blocks and the boundaries of the blocks were paint-blazed, designated by numerals or letters, and cleared of brush sufficiently to permit walking. The spring drumming site counts were taken to determine as accurately as possible the number of drumming male grouse on the study area. If a sex ratio of one male to one female is assumed, it is simple arithmetic to multiply the number of males by two and thus obtain an estimate of the population available for spring breeding. The existence of a one to one sex ratio in grouse has been fairly well substantiated by other investigators (Bump, 1932, Bezdek, 1944). The average clutch size in grouse was found to be 11 in New York State (Bump, 1935) and there is no reason to believe it would be different in Connecticut. If the average clutch size (11) is multiplied by the number of female grouse on an area, the result will be the grouse breeding potential of the area. Thus the ultimate purpose of the drumming site count was to determine the spring breeding population and the breeding potential of the ruffed grouse on the study area. Grouse censusing by the King method (Fisher, 1939) has been used on this study area since the fall of 1940, and the populations as determined by the drumming site counts have been compared with the populations as computed by the King method. The drumming act of ruffed grouse has been described in numerous publications (Sawyer, 1923, Bent, 1932) and will not be presented in this paper. The censusing of ruffed grouse by the determination of territories has been attempted by Clarke (1936) who used drumming sites in conjunction with other indicators, and by King (1939). 1 In 1941 and 1946 surveys were made by the author; in 1943, 1944, and 1945, by Mr. M. Arnold; and in 1942 by Messrs. M. Alexander, W. Fitzwater and M. Arnold.