Effects of Dietary Protein Levels on Ruffed Grouse Reproduction

Abstract

The effects of 5 dietary protein levels on reproduction of captive female ruffed grouse (Bonasa umbellus) were studied at Guelph, Ontario. Isocaloric rations containing protein levels (% dry matter) of 7.6, 11.5, 13.6, 17.0, and 20.1 were supplied to 5 test groups on 24 February 1979. Although test groups began laying about the same date, increases in dietary protein level were associated with linear increases for duration of laying, rate of laying, clutch size, weight of the first egg, mean egg weight, clutch weight, hatching success, chick weight at hatching, and chick survival (P 0.05). Clutches of eggs of wild ruffed grouse from the Guelph area were compared with the reproductive success of the captive birds. The wild birds were most notable for their shorter duration and greater rate of laying, mean egg weight, fertility, hatching success, and chick weight at hatching. J. WILDL. MANAGE. 46(3):569-579 There is evidence to suggest that spring diets of several grouse (Tetraonidae) species are important for restoring depleted body condition and in affecting breeding success (Siivonen 1957, Moss et al. 1975). Studies of ruffed grouse show this species to have low body reserves of lipid and glycogen and large reserves of protein during the winter months (Thomas et al. 1975). Should such reserves be used at times of low temperature and poor snow cover, ruffed grouse probably enter the breeding season in poor condition as suggested by Gullion (1967). In some winters, ruffed grouse select aspen (Populus sp.) buds with the highest protein content (Doerr et al. 1974), suggesting a high requirement for food plant protein. Therefore, protein nutrition may be an important factor affecting reproduction of ruffed grouse. To investigate this possibility we evaluated the effects of several levels of dietary protein on various indicators of reproductive success of ruffed grouse. We thank J. L. Atkinson for technical support during the study and for manuscript review. We are grateful to V. G. Thomas for helpful comments on the manuscript and to M. Beckerton, A. Garbutt, E. Nancekivell, and K. Wylie for assistance. R. J. Hines provided statistical consultation throughout the project. Dawes Laboratories of Canada Ltd., Weston, Ontario supplied the vitamin-mineral mix for the rations. This study was inanced by an Ontario Graduate Scholarship, University of Guelph Bursary/ Scholarship and through grants from the Ontario Ministry of Natural Resources and the Natural Sciences and Engineering Research Council (Grant A6495) to A. L. A. Middleton.