This Handbook is the result of a cooperative effort between the Forest Service, U.S. Department of Agriculture, and the Fish and Wildlife Service, U.S. Department of the Interior. Authors Scott and Stone are wildlife research biologists with the Fish and Wildlife Service's Denver Wildlife Research Center. Scott is stationed in Fort Collins, Colorado. Authors Evans and Patton are principal wildlife biologists with the Forest Service's North Central Forest Experiment Station and Rocky Mountain Forest and Range Experiment Station, respectively. Evans is stationed in Columbia, Missouri, in cooperation with the University of Missouri, while Patton is stationed in Tempe, Arizona, in cooperation with Arizona State University.

Special thanks are due Arthur Singer, who graciously donated the use of his illustrations from "A guide to field identification: Birds of North America," by Robbins, Bruun, and Zim, which are reproduced here with permission of the Western Publishing Company. The distribution maps are also reproduced with the permission of Western Publishing Company. © Copyright 1966 by Western Publishing Company, Inc.

We would like to thank Kimberly Hardin, Beverly Roedner, Mary Gilbert, Steve Blair, and Michael, Leslie, and Mary Stone for their assistance in collecting literature. A special thanks to Jill Whelan for her assistance in literature searches, checking references and scientific names, and assembling this publication. The assistance of Robert Hamre in encouraging and guiding the preparation of this manuscript is acknowledged and very much appreciated.