PREFACE. 
The present report is a continuation of a systematic account of the vertebrate animals of 
North America, collected or observed by the different parties organized under the direction of the 
War Department for ascertaining the best route for a railroad from the Mississippi river to the 
Pacific ocean. 
The collections of these expeditions having been deposited with the Smithsonian Institution 
by the War Department, in compliance with an act of Congress, the undersigned was charged 
by the Secretary of the Institution with the duty of furnishing the series of general reports 
upon them, as called for by the Department. The account of the mammals having been 
published in 1857, that of the birds is herewith furnished, prepared according to the plan 
announced in the preface to that volume. 
As in the volume on the mammals, by the insertion of the comparatively few species not noticed 
by the expeditions, this report becomes an exposition of the present state of our knowledge of the 
-birds of North America, north of Mexico. This addition, while rendering the work mcre valuable 
to the reader, was absolutely necessary for the proper understanding of the western fauna, the 
species of which are generally so closely allied to:the eastern forms as to require in most cases 
more minute and detailed descriptions of the latter than have been published. 
Certain portions of the report have been prepared by Mr. Joy Cassin, of Philadelphia, and 
Mr. Georce N. Lawrence, of New York, well known as the leading ornithologists of the United 
States. Mr. Cassin has furnished the entire account of the 2aptores, from p. 4 to 64, of the 
Grallae from p. 689 to 753, and of the Alcidae from p. 900 to 918, in all about 155 pages. Mr. 
Lawrence has written the article on the Longipennes, otipalmes, and Colymbidae, from page 
820 to 900, making 80 pages. 
To Mr. P. L. Sclater, of London, acknowledgments are due for the examination of certain 
specimens in European museums, and for other valuable aid in determining points of synonymy ; 
some of his notes received too late for insertion in their proper places will be found in 
Appendix A. Much assistance has also been rendered in various ways by Dr. J. G. Cooper. 
In the introduction to the general report upon the mammals will be found a detailed account 
of the different railroad surveying parties from which zoological collections were received, 
with their respective routes. For the proper understanding of the subject, however, it will bo 
necessary to present a brief recapitulation in this place. 
1. Line oF THE 47TH PARALLEL, UNDER Governor [. I. Stevens.—This consisted of two principal 
parties, one under Governor Stevens, passing from St. Paul, Minnesota, to the Pacific, 
accompanied by Dr. George Suckley, U.S. A, as surgeon and naturalist, the other under 
Captain G, B. M’Clellan, proceeding from Vancouver to the Cascade mountains, accompanied by 
