Egg loss among spruce grouse inhabiting lodgepole pine forests

Abstract

The loss of eggs from clutches deposited in simulated and natural nests of spruce grouse was investigated during the spring of 1983 in lodgepole pine forests of southwestern Alberta. Two-thirds of all clutches, both in simulated and natural nests, were partially or completely lost. Density of simulated nests had no impact on proportional loss. Evidence suggests that nests under a conifer-dominated canopy, in an area lacking extensive shrub coverage, and at distances greater than 15 m from trails were the most vulnerable to egg predators. We conclude that red squirrels were the principle predator destroying these clutches.