Comparative Notes on the Life History of the Carolina Chickadee1
COMPARATIVE NOTES ON THE LIFE HISTORY OF THE CAROLINA CHICKADEE1 RICHARD BREWER knowledge of the life histories of closely related organisms is basic to A understanding their ecological and evolutionary relationships. The Carolina and Black-capped Chickadees (Parus carolinensis Audubon and P. atricapillus Linnaeus) are sibling species occupying essentially allopatric breeding ranges. Where their ranges are contiguous in western Illinois and eastern Missouri, interbreeding apparently occurs, with the production of a zone in which a large proportion of the birds may be hybrids. This paper presents information on certain aspects of the life history of the Carolina Chickadee, along with comparative material on the Black-capped Chickadee and on a population occurring at the line of contact between these two species. Appreciation is due S. C. Kendeigh, who directed the study. Many persons have aided me through discussion or by assistance in field work; particularly, I am indebted to G. W. COX, W. L. Gillespie, and G. C. West. For supplying me with much valuable information through correspondence, I extend my thanks to K. L. Dixon, L. D. K. Lawrence, C. McMullen, J. T. Tanner, and especially to H. Brackbill and A. Laskey whose sizable contributions are cited specifically in the appropriate sections beyond. My wife, Lucy Sharp Brewer, assisted in tending and observing young in the laboratory. Work during the years 1956-1959 was supported by National Science Foundation pre- doctoral fellowships. PROCEDURE Field work was conducted from October 1954 to November 1959. Although some supplemental observations were made in Indiana, Michigan, Mis- souri, North Carolina, Tennessee, and Texas, the principal areas of investiga- tion were the following counties of Illinois: Bond, Champaign, Clinton, Coles, Cumberland, Douglas, Effingham, Fayette, Jackson, Piatt, Randolph, Shelby, Washington, and Williamson.
[Show full text]