Notes on the American Sparrow Hawk

THE American Sparrow Hawk (Falco sparverius) occurs abundantly throughout the nation and has been well known to science for many years.In spite of this familiarity, knowledge of its natural history is rather sketchy.The accounts in the literature, with few exceptions, are primarily concerned with distribution records, nesting dates, and food habits, plus scattered descriptions of behavior (see Friedmann, 1950: 726-739).The present study was undertaken to investigate some of the less well known aspects of the life of the Sparrow Hawk.Field observations were made at Corvallis, Oregon, from January 1951 to September 1952, and at Bend, Oregon, from September 1952 until December 1954.Notes made prior to 1951 in California, New York, and Virginia were also utilized.Fourteen captive birds kept for varying periods provided supplementary data.Additional information came from a number of sources.The Banding Office of the U.S. Fish and Wildlife Service supplied data on Sparrow Hawk banding returns up to 1953.A postcard questionnaire requesting data on sex ratios and plumages was sent to 50 museums and zoos throughout the United States and Canada, and information on 1952 specimens was obtained.Dr. Alden H. Miller of the University of California and Dr. Robert W. Storer of the University of Michigan kindly supplied weight data for specimens in the collections at their respective institutions.Dr. K. L. Gordon of Oregon State College was especially helpful in preparing the manuscript, and the Braly Egg Collection