Ecology of the great gray owl.

Abstract

Information is needed on the great gray owl to understand its ecology and to consider this species in land management decisions. From 1982 to 1988, we studied 24 pairs and 107 juvenile great gray owls in northeastern Oregon. Forty-nine nests were located; 16 were used more than once, so we observed 71 nesting attempts. Seventy-eight percent of these nesting attempts were successful in raising 1 to 5 young (mean = 2.2). The nests were on stick platforms, on top of broken-off dead trees, and on artificial wooden platforms. Nest trees occurred in a variety of habitats, although most were in mature or older, unlogged stands of mixed conifer. Diet by biomass consisted mainly of northern pocket gophers (67 percent) and voles (27 percent). The size of the home range for 16 adult owls and 19 juvenile owls averaged 67 square kilometers and 157 square kilometers, respectively. Management practices enhancing habitat for great gray owls include providing artificial nest platforms, protecting existing nest platforms and large-diameter dead trees, providing dense tree cover around or adjacent to the nest, and providing perches for recently fledged young.

Citation

Bull, Evelyn L.; Henjum, Mark G. 1990. Ecology of the great gray owl. Gen. Tech. Rep. PNW-GTR-265. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 39 p