Recovery Plan for the Northern Spotted Owl - DRAFT

iTable B.7. Comparison of structural features at nest sites and throughout neststands used by northern spotted owls.A. Klamath and California Coast provinces(data from LaHaye 1988)Sturctural Nest Nestfeature Value site standCanopyClosure % 81 74Trees per 11-24" 63 42acre 25-36" 17 3by dbh >36" 6 1classBasal area ofsnags by dbh >15" 23 14aft2acB. California Coast (data from Folliard andReese 1991, and Diller and Folliard, pers.comm.)Structural Nest Nestfeature Value site standCanopyClosure% 92 94B. continued-Structural Nest Nestfeature Value site stand% of live 16"871406419378 5813 7Trees peracreby dbhclass5-10"11 -20"21-36">36"81 13651 5723 187 2continues-No. of snagsper acre 0part of the Klamath province in California. In all studies, the average numberof trees decreased as diameter increased (i.e., in the 'reversed J" patterndiscussed in Appendix G). The hardwood understory was well-developed inutilized sites in California but was essentially absent in utilized sites elsewhere.Average snag density in utilized sites was similar to average snag density inold-growth sites except in the California Coast province where few snagsoccurred in utilized sites. Average values were similar for nesting, roosting,and foraging sites. No major differences were apparent between averagevalues for sites and for stands containing the sites.Review of Tables B.2 through B.9 indicates that information from California ismuch more complete than information from Oregon and Washington. Thework by Allen et al. (1989) on roosting and foraging sites in the OlympicPeninsula and western Washington Cascades provinces and by Buchanan(1991) on nest sites in the eastern Washington Cascades are the only extensivestudies yet reported. Additional information for Oregon and Washington willbe available soon from studies currently in progress. Studies in the OregonKlamath, Oregon Coast Range, and eastern Oregon Cascades provinces alsowould be valuable.299