Introduction 



This is the twentieth in a series of bulletins of the United States 

 National Museum on the life histories of North American birds. 

 Previous numbers have been issued as follows: 



107. Life Histories of North American Diving Birds, August 1, 1919. 



113. Life Histories of North American Gulls and Terns, August 27, 1921. 



121. Life Histories of North American Petrels and Pelicans and Their Allies, 



October 19, 1922. 

 126. Life Histories of North American Wild Fowl (part), May 25, 1923. 

 130. Life Histories of North American Wild Fowl (part), June 27, 1925. 

 135. Life Histories of North American Marsh Birds, March 11, 1927. 

 142. Life Histories of North American Shore Birds (pt. 1), December 31, 1927. 

 146. Life Histories of North American Shore Birds (pt. 2), March 24, 1929. 

 162. Life Histories of North American Gallinaceous Birds, May 25, 1932. 

 167. Life Histories of North American Birds of Prey (pt. 1), May 3, 1937. 

 170. Life Histories of North American Birds of Prey (pt. 2), August 8, 1938. 

 174. Life Histories of North American Woodpeckers, May 23, 1939. 

 176. Life Histories of North American Cuckoos, Goatsuckers, Hummingbirds, and 



Their Allies, July 20, 1940. 

 179. Life Histories of North American Flycatchers, Larks, Swallows, and Their 



Allies, May 8, 1942. 

 191. Life Histories of North American Jays, Crows, and Titmice, January 27, 



1947. 



195. Life Histories of North American Nuthatches, Wrens, Thrashers, and Their 



Allies, July 7, 1948. 



196. Life Histories of North American Thrushes, Kinglets, and Their Allies, 



June 28, 1949. 



197. Life Histories of North American Wagtails, Shrikes, Vireos, and Their 



Allies, June 21, 1950. 

 203. Life Histories of North American Wood Warblers, June 15, 1953. 



The same general plan has been followed, as explained in previous 

 bulletins and need not be repeated here. The nomenclature of the 

 1931 Check-List of the American Ornithologists' Union, with its 

 latest supplements, has been followed. 



Many who have contributed material for previous volumes have 

 continued to cooperate. Receipt of material from over 530 contrib- 

 utors has been acknowledged previously. In addition to these, our 

 thanks are due to the following new contributors: Hildegarde C. 

 Allen, F. S. Barkalow, Jr., Ralph Bcebe, H. E. Bennett, A. J. Berger, 

 Virgilio Biaggi, Jr., C. H. Blake, Don Bleitz, B. J. Blincoe, L. C. 

 Brecher, Maurice Broun, J. H. Buckalew, H. L. Crockett, Ruby 

 Curry, J. V. Dennis, M. S. Dunlap, J. J. Elliott, A. H. Fast, Edith 



VII 



