May, 1922 THE ALEUTIAN ROSY FINCH 89 
low, the tips only retaining the dark color. No shedding of the horny sub- 
stance of the mandible takes place; it is merely a matter of coloration; and 
for what reason? 
I have been led to believe that there is an irregular migration—or perhaps 
it might properly be called a flight—of Pribilof Rosy Finches to the Aleutian 
Islands in winter. There appeared to be a fluctuation in the numbers of the 
birds which could be explained in no other manner. They do not all leave the 
Pribilofs at any season, regardless of severity of the weather, and weather con- 
ditions could not be correlated in any way with the variation in their abund- 
anee. While it is possible that these variations might be such in appearance 
only, due to flight to portions of the resident island rarely visited by man, 
eareful study of the subject through several winters did not satisfy me that 
this was the ease. 
These birds continued to be abundant from 1913 up to the winter of 1916- 
17, when a terrible catastrophe befell them. The Pribilofs that winter were 
_ visited by a number of gyrfaleons, and these wreaked havoc among the resi- 
dent land birds. Dr. Harold Heath has outlined the case of the Alaska Wren, 
as regards fluctuations in numbers (Condor, vol. 22, 1920, p. 49). The Rosy 
Finches, as these leucostictes are locally known, fared lttle better. The first 
gyrfaleons killed were examined, and in their stomachs was found unmistak- 
able evidence of slaughter—the rosy feathers of their victims. Their prey 
was so easily captured on the barren Pribilofs that the faleons became extra- 
ordinarily fat. So oily were they that the preparation of specimens was ex- 
ceedingly difficult. The offering to the natives of a bounty of one dollar for 
each capture was instrumental in securing thirteen of them, a greater number 
than the total which had been seen on the Pribilofs since observations com- 
menced. 
During the winter season the rosy finches remain in the immediate vicinity 
of the cliffs. This made them easy of capture by the gyrfalcons. which seemed 
to be especially at home in such surroundings. When the summer of 1917 
came. scarcely a finch could be found. Only one pair nested on St. Paul, and 
one pair on Otter Island. A few more were left on St. George. but the species 
would have been classed as exceedingly rare even there. The total number 
was not over twenty-five, which is an optimistic estimate. How fortunate it 
is that the seal islands are normally free from such a scourge as these falcons 
proved to be! 
Through succeeding years the rosy finches were watched with great 
anxiety, and it was gratifying to see their numbers gradually increasing. By 
1920 there were, perhaps. a dozen pairs on St. Paul Island and a hundred on 
St. George. but even the latter was still underpopulated. 
This circumstance serves as a fair illustration of the precarious existence 
led by island birds in general. In the short space of two or three months a 
species may.be almost entirely annihilated by the sudden anvnearance of an 
enemy that is normally absent. The rarity of the Aleutian Rosv Finch else- 
where in its range is commonly believed to be due to the work of birds of prey 
there found. Singular to relate no hawk, eagle, or owl lives on the Pribilofs 
except as a straggler. | 
Two indicators of spring mark a point in the Aleut’s calendar. One of 
these is the coming of the Least Auklets (Choochkies) with clock-like regular- 
