INTRODUCTION 13 



other island race, the Coues' Gadwall, is confined to two small islands of the Fanning 

 group. Ten other species are confined to islands. 



Distributions are taken up in detail under the account of each species, and maps 

 are used to give a graphic picture of the range. These maps should be considered as 

 giving only a general picture, for many large areas have to be included which are not 

 favorable to water-birds for various reasons. Some of these features are deserts or 

 mountain ranges, or regions of deep lakes with steep rocky shores. 



Migration. We understand only a few facts in regard to migration. We know 

 that certain species arrive in certain regions at certain times, but we do not know 

 the extent of territory over which the individual passes in a given year. We know 

 that there are summer movements, males collecting in definite areas after leaving 

 the females, and banded birds have recently brought out the fact that there are 

 summer dispersals, often in a northerly direction, about which we know almost 

 nothing. We commonly think of the ducks migrating south in autumn, and this of 

 course is true, but Allan Brooks has told me of extensive movements of male Scoters 

 on the fourth of July, along the Pacific Coast. 



Ducks banded at Bear River, Utah, have been taken all over the West, from Cali- 

 fornia to the Mississippi Valley, and north to the Canadian line. There are no simple 

 north and south migration routes, but as far as we can see an endless complexity of 

 movement. 



It is best in studying this subject to admit at the start that our picture of it is only 

 the crudest beginning, nor do we know anything of the "sixth sense" that keeps the 

 bird oriented, "lone wandering but not lost," as Bryant has so beautifully expressed 

 it. The subject is complicated in so many ways that the species, the sex, and per- 

 haps even the exact age, must be taken into account, and the direction of movement 

 is not necessarily the same for the same species in different localities. For instance, 

 many western-bred Canadian ducks bear east and south to reach the Atlantic sea- 

 board, but they do not necessarily return by the same road, nor do all individuals in 

 a given breeding locality occupy the same winter quarters. Western-bred ducks 

 banded at Lake Erie on migration do not all go to the Atlantic seaboard; some con- 

 tinue south to the Gulf Coast. Then again we know that the White-winged Scoter, 

 whose breeding area is restricted to a rather small section west of James and Hudson 

 Bays, migrates both to the east and to the west, and although it does not breed on 

 either coast, enormous numbers of non-breeders spend the summer on the Atlantic 

 and Pacific shores. 



In Europe records from banded Mallards show a tendency for those nesting in 

 Sweden, East Prussia, and Kurland, to migrate southwest in autumn, and with 

 Pintails there is a definite interchange between the west coast of Denmark and Fin- 



