Nest-Site Characteristics of White-Headed Woodpeckers

Abstract

We described nest tree and site characteristics of 53 nests of the northern race of the whiteheaded woodpecker (Picoides albolarvatus albolarvatus) from the central and southern Sierra Nevada, California. We located nests in a variety of habitats and in most tree species, although 89% were in pines (Pinus spp.) and firs (Abies spp.). Nests were located near the ground (f = 3.0 m above ground level). The mean diameter breast height (dbh) of nest trees on 2 mapping grids, where some of our nests were located, did not differ (P > 0.80, P > 0.20) from random samples of snags on the corresponding grids. Most snags used for nest cavities were in a moderate state of decay. Existing snag-management policies of the U.S. Forest Service (USFS) in California will probably provide sufficient snags of the right diameter classes for whiteheaded woodpeckers, provided interactions with other cavity nesters does not limit their use of nest sites. J. WILDL. MANAGE. 53(1):50-55 Woodpeckers and other cavity-nesting birds are increasingly threatened by the reduction of snags in forest ecosystems (Vincent 1966, Short 1973). Snag requirements for many cavity-nesting species are known for particular sites but the characteristics of nests of a single species over a broad array of habitats are rarely examined. Raphael (1980:174) emphasized the need to study the characteristics of nest sites of cavitynesting birds over many forest types to reveal the range of acceptable nest conditions and the flexibility of bird preference over a wide range of snag characteristics. 1 Present address: Intermountain Forest and Range Experiment Station, 800 Block E. Beckwith, Missoula, MT 59807. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:41:16 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 53(1):1989 WHITE-HEADED WOODPECKER NESTS * Milne and Hefl 51 The white-headed woodpecker is a common primary cavity nester in the Sierra Nevada, but little quantitative information has been published on its nest-site requirements. Our objective was to describe various characteristics of the nest sites and nest trees of this species in the Sierra Nevada and relate these characteristics to snag-management policies of the USFS in California. Numerous field assistants worked on the studies in the Sierra Nevada. We thank those who found white-headed woodpecker nests. We appreciate the constructive comments about the manuscript by M. T. Chapel, J. A. Jackson, R. W. Mannan, M. L. Morrison, M. G. Raphael, J. Verner, and 2 anonymous reviewers. We also thank K. L. Garrett and the Western Foundation of Vertebrate Zoology and J. D. Lowe and the Cornell Laboratory of Ornithology for their nest records. STUDY AREA AND METHODS We obtained nesting records from 3 USFS studies on the western slope of the central and southern Sierra Nevada, California. The studies were conducted in the summers of 1980-83 (Verner and Ritter 1983), 1983-85 (Hejl 1987), and 1985-88 (J. Verner, USFS, pers. commun.) in the Sierra National Forest, and Sequoia and Yosemite national parks. Verner and Ritter (1983), Labinger et al. (1988), Lovio et al. (1988b), and Hejl (1987) describe the study areas. Nests of white-headed woodpeckers were located incidental to the main objectives of each