ba 
eects 
MUS. CO} 
Alaskan Bird Migrations 
by 
Donald R. Griffin 
Cornell University 
Despite the plentiful navigation aids provided for our airplanes, 
poor visibility still presents major problems and hazards. Passengers 
and pilots alike feel isolated and somewhat “lost” when flying at night 
or in thick weather. Hence, it is only with a feeling of humility that one 
compares human air navigation to the bird migrations, which cover 
thousands of miles from the Arctic to the Tropics, without the aid of 
engines or instruments. Could our air navigation profit from a study of 
the methods employed by birds to guide their flight over trackless 
stretches of land or ocean? Before we can answer such a question, we 
must first know what the birds’ methods really are. 
First, it might be well to question why millions of birds bother to 
fly north at all. Why should they leave the temperate latitudes for the 
exertion and hazard of long annual migrations? Crowding, competition 
for nesting space, and even memories of ancestors who lived millions 
of years before--all of these factors have been suggested to account for 
the annual mass movement (Thompson, 1926). 
Only recently another factor has attracted attention--the length of 
daylight, which depends directly on latitude. There have been fewactual 
attempts to study this matter in the Arctic; hence, I should like to men- 
tion an observation which seems to be significant in this connection. 
In. 1948 scientists from Cornell made continuous observations of 
nesting birds, at Point Barrow, Alaska, for from 24 to 48 hours at a 
stretch. They found that in the continuous daylight of late June (69°23’ 
North latitude) robins brought food to the young during 21 hours of the 
day, resting for only three hours in the middle of the night when the 
temperature was just above freezing. In contrast, the same species 
(Turdus migratorius) in the northern United States feeds its nestling 
young for only about 16 hours a day. The arctic robins made anaverage 
of 137 feeding trips per day, compared to 96 made by the others. More 
important, the arctic birds matured faster--the brood observed left the 
nest 8.8 days after hatching, compared to an average-of 14 days for the 
same species in the northern U.S. Now it is well known that the period 
when young birds must remain in the nest is one of the most dangerous 
in their lives, for they are helpless and readily located by enemies. 
Thus, it seems possible that shortening of the nestling period increases 
their chance of survival enough to justify the migration to the arctic la- 
titudes; but further study is necessary to find a definite answer. 
Donald R. Griffin (B.S and Ph.D. Harvard University) is well known 
for his studies on the use of ultrasonic sound by bats to guide themselves 
through darkness. His other researchinterests have included investiga- 
tions of the physiology of protection from cold (in men and animals) and 
various aspects of physiological optics and acoustics. At present he is 
Associate Professor of Zoology at Cornell. He first presented the 
material contained in this article at a meeting of the Alaskan Science 
Conference held earlier this year. " 
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