sufficient detail to indicate the usual movements of each species; it is obviously impossible to give, in a general work of such large scope, all records of occurrence and all dates and no pretense at perfection in this direction is claimed. Many published records, impossible to either verify or disprove, have been accepted if they are apparently within the known limits of ranges.
The nesting dates are the condensed results of a mass of records accumulated from the data in over 60 of the largest egg collections in the country, as well as from contributed field notes and from many published sources. They indicate the dates on which eggs have been actually found in one or more portions of the breeding range of the species, showing the earliest and latest dates and the limits between which at least half of the dates fall. The names of colors, when in quotation marks, are taken from Ridgway's Color Standards and Nomenclature (1912 edition) and the terms used to designate the shapes of eggs, when in quotation marks, are taken from Ridgway's Nomenclature of Colors (1886 edition). The heavy-faced type in the measurements of eggs indicate the four extremes of measurement.
After a few introductory remarks where these seem desirable, the life history of each species is written in substantially the following sequence: Spring migration, courtship, nesting habits, eggs, young, sequence of plumages to maturity, seasonal molts, feeding habits, flight, swimming and diving habits, vocal powers, behavior, enemies, fall migration, and winter habits. An attempt has been made to avoid repetition in dealing with subspecies.
Although preference has been given to original unpublished material, so little of this has been received that it has seemed best to quote freely from published material whenever the life history could be improved by so doing. The author does not guarantee the correctness of any statements quoted, but has selected only such as seem to be reliable. Quotations from or references to published matter are indicated by a date in parentheses after the author's name and the reference may be found by turning to the bibliographical index at the end of each part.
Acknowledgments are due to many who have helped to make the work a success, by contributions and by sympathetic encouragement. Dr. Louis B. Bishop has contributed many hours of careful work in collecting from published material and other sources a mass of data needed for the distributional part of this work and has helped to tabulate and arrange it. He has also been very helpful to the author in his studies of plumages and has helped and encouraged him in many ways. Dr. Charles W. Townsend has furnished a lot of original contributions, has read over and corrected much of the manuscript and has written the entire life histories of the puffin and
