Ruffed Grouse Adrenal Weights Related to Population Density

Abstract

Twenty male ruffed grouse (Bonasa umbellus) were collected during May on six study areas for which population estimates were available, based on drumming counts. A positive correlation was shown between the ratios of adrenal weights to body weights and population density. A negative correlation was found between the ratios of the adrenal weight to body weight and the proximity of the neighboring drumming log. Evidence of crowding can be seen in the change of weight of dominant animals, especially the weight of the adrenal gland, thymus, and spleen (Christian and Davis 1966). There is little in the literature on adrenal weights in gallinaceous birds, or of a relationship of adrenal weights to population density in the field. This paper presents the latter type of data for a small but possibly indicative sample of ruffed grouse. The adrenal sample was collected in the spring of 1966 from active males on drumming sites on six study areas within a 50mile radius of Fredericton, New Brunswick. The data were used in a thesis on population dynamics of ruffed grouse by the first author in partial fulfillment of the requirement for the Master of Science Degree at the University of New Brunswick. We acknowledge the assistance of Dr. J. G. Eales and T. Dick.