82 University of California PuMications in Zoology [you 21 



Under the circumstances the only way of definitely indicating my 

 opinion of each and all of the specimens serving as the basis for the 

 conclusions formulated in this study, for the benefit of any future 

 student of the group, was to list each individual bird handled. This 

 I have done, with but few exceptions. For some time before settling 

 down definitely to a careful study of this subject, I had kept notes 

 upon the series of fox sparrows sent to the Museum for identification. 

 It was not possible, later on, to reexamine all of these birds, and while 

 I have used data regarding distribution, etc., acquired from such 

 specimens, I have not been able to enter them all in the lists of speci- 

 mens examined. Thus the charts showing the relative abundance 

 during winter of different subspecies in different parts of California, 

 are based in part (though in but a small degree) upon specimens not 

 entered in the lists. 



There are in each series of winter birds certain equivocal specimens 

 that are hesitatingly referred to one subspecies or another, thougli 

 typical of none. When such doubtful birds happen to have come 

 from points outside the winter metropolis of the race to which they 

 are referred, they are not included in the diagrammatic charts of 

 winter visitants (tables 1, 2, 3). 



For obvious reasons it was not possible for me to use published 

 records of occurrence without examining the specimens upon which 

 such statements were based. Consequently, I have ignored all such 

 records. The spots upon the maps herewith presented are each one 

 indicative of a specimen or specimens handled by myself; they reflect 

 my own opinion of the proper classification of that specimen, and not 

 the published idea of someone else. 



Birds are catalogued in the lists of specimens examined, as to sex, 

 and also as to age, being indicated as adult ("ad."), immature 

 ("im. "), or juvenile ("juv. "). These terms are used with definitely 

 restricted meanings. "Juvenile" is correlated with the juvenile 

 plumage, the soft, lax feathers following the natal dowai, and worn 

 for but a few weeks. ' ' Immature ' ' applies to the first annual plumage, 

 following the juvenile stage, and usually acquired in Passerella in 

 August or early September. I have been unable to detect any certain 

 and constant differences of plumage between 3'oung and adult fox 

 sparrows after the annual late summer molt, but young and old may 

 be differentiated for some months thereafter, sometimes until Decem- 

 ber, by examination of the skull when the bird is skinned. Collectors 

 for the Museum of Vertebrate Zoology have been carefully instructed 



