18 THE CONDOR Vol. XXII 
Washington, Oregon, and British Columbia, but in Alaska it is a summer visit- 
ant only (see Swarth, Alaska Expedition of 1909, p. 89). Mr. Swarth’s recent 
study of the different races of Fox Sparrows shows that those which pass the 
summer farthest north have their winter homes in the southern part of the range 
of the group as a whole. Some other birds show the same tendency. It is easy 
in Berkeley to observe the migration of Pileolated Warblers after the race which 
nests in this locality has settled down to domestic life. 
If the same thing happens in the ease of the Rusty Song Sparrow, it would 
seem probable that my visitor summers in Alaska, in the only part of the range 
which does not support these birds during the winter months. A feeding-table 
in California has proved an attraction which has led the bird to return year 
after year. But he has never brought another of his own race with him. How 
much longer will he come? How many years does a migratory bird live? 
The evidence presented by the return of the banded Fox Sparrow and the 
Rusty Song Sparrow seems to show, in addition to the wonderful sense of diree- 
tion which guides birds in their migrations, a very strong attachment to a local- 
ity as long as favorable conditions exist there. They have proved that they can 
find their way from one spot to another perhaps thousands of miles away and 
back again to the same spot. If they can and do return to their winter niche, it 
seems to me not unreasonable to suspect that they may do the same thing in the 
summer time. Many of the arguments recently presented favoring the theory of 
a permanent marital tie among birds seem to me to point to the probable remat- 
ing of a large number of former pairs as brought about by this attachment to a 
definite locality. Changes effected by tragedies and by the influx of the new 
generation might account for exceptions to a general rule. Until, at least, more 
evidence is collected as to the actual return of birds to the same locality, the 
question of frequent re-mating is not disposed of, no matter how weak the bio- 
logical evidence for a permanent marital union may be. 
Berkeley, Califorma, December 8, 1919. 
A PECULIAR FEEDING HABIT OF GREBES 
By ALEXANDER WETMORE 
. ANY ornithologists have commented briefly upon the fact that quantities 
of feathers almost invariably are present in the stomachs of grebes, a pe- 
culiarity that has been without apparent explanation. The present writer 
through reading and personal observation has been -familiar with this condition 
for many years, and recently, during a study of the food of our North American 
Grebes (for which the stomachs of nearly four hundred individuals were exam- 
ined), has had it brought to his attention most forcibly. The following notes 
based upon personal observation, while presented as theoretical, may be of as- 
sistance in throwing light upon the reason for this strange diet. 
