6 PACIFIC COAST AVIFAUNA No. 7 



However, there will be found exceptional instances, particularly as to times 

 of migration, which will not come within the dates as given here. This, of 

 course, is to he expected, as it is a well-known fact that individuals or small 

 companies of many species either precede or straggle behind the main migra- 

 tory body. 



Especially is this true in the case of many of the water-birds, which are 

 frequently noted along our coast at times when, according to the general dates 

 as given here for their migrations, they should he engaged in incubating their 

 eggs or raising their young in a more northern latitude. Some of these strag- 

 glers may have dropped behind the main body of their species as the result 

 of wounds or disease which render them incapable of making the long north- 

 ward journey to their breeding grounds. In some instances where the species 

 does not mature the first year, many of the immature birds may remain with 

 us, while the mature birds of their species go north to perform their reproductive 

 duties. This is particularly noticeable in the case of the scoters. 



In some other species, ordinarily migratory, there seem to be a consi lerable 

 number of individuals that are non-breeders. These non-breeding birds are 

 frequently noted with us during the summer months. Especially is this true 

 with the turnstones. tattlers and many other waders. There is also a consid- 

 erable variation from year to Vear in the dates of the migrations of many species, 

 probably due principally to the condition of the weather and the food supply. 

 Some species, also, maintain different routes of migration in spring and fall. 

 They may be abundant in a certain locality during the fall migration and '•are 

 in the spring, or vice-versa. 



Taking all these facts into consideration, it is easily seen that migration 

 dates, while they may be substantially correct, are bound to be far from infallible, 

 and exceptional instances, instead of being regarded as surprising, are to he 

 expected. 



The number in parenthesis at the right of the running number in the list is 

 that given the species in the A. O. U. Check-List. 



I have aspired to make this list as complete and as correct as possible; 

 and with this end in view I have gone over all obtainable literature on the 

 birds of this region and have culled thoroughly my own notes and those of 

 many other students of the birds of the region. For all errors of commission 

 or omission I ask the indulgence of the reader, and freely invite correction or 

 criticism, realizing that absolute freedom from error in a list of this kind is 

 an impossibility. 



