INTRODUCTION 



This is the twelfth 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 2-5, 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. 

 107. 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. 



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

 bulletins, and the same sources of information have been utilized. 

 The nomenclature of the 1931 check list of the American Ornitholo- 

 gists' Union has been followed, but it has seemed best to continue in 

 the same order of arrangement of families and species as given in the 

 old check list (1910). 



An attempt has been made to give as full a life history as possible 

 of the best-known subspecies and to avoid duplication by writing 

 briefly of the others and giving only the characters of the subspecies, 

 its range, and any habits peculiar to it. In many cases certain habits, 

 probably common to the species as a whole, have been recorded for 

 only one subspecies; such habits are mentioned under the subspecies 

 on which the observations were made. The distribution gives the 

 range of the species as a whole, with only rough outlines of the ranges 

 of the subspecies, which cannot be accurately defined in many cases. 



The egg dates are the condensed results of a mass of records taken 

 from the data in a large number of the best egg collections in the 

 country, as well as from contributed field notes and from a few pub- 

 lished sources. They indicate the dates on which eggs have been 

 actually found in various parts of the country, showing the earliest 

 and latest dates and the limits between which half the dates fall, the 

 ]ieight of the season. 



The plumages are described in only enough detail to enable the 

 reader to trace the sequence of molts and plumages from birth to 

 maturity and to recognize the birds in the different stages and at the 

 different seasons. No attempt has been made to describe fully the 



