Pt. Borrow 
BE AUFORT SEA 
Ory tundra 
i 
ECON TEE RIN CS 
MOUNTAINS 
Figure 4. Map of arctic coastal plain of Alaska. A, B, and C are points 
where semipalmated plovers were released to test their ability to find 
their way home to theirnests at Umiat. Also shownare the points where 
alarge flockof snow geese was observed and the distance evidently flown 
by these birds during four hours of non-migratory cruising. 
Semipalmated plovers (Charadrius hiaticulatus semipalmatus), nesting 
at Umiat on the Colville River, proved well suited to homing experiments, 
except that the number of nesting pairs accessible to us was too small 
to permit homing experiments on the scale desirable. The few birds 
available, however, gave results comparable to homing experiments in 
temperate latitudes. 
Since the birds would have been frightened by observers watching 
too close to their nests,a different methodof recording their movements 
was devised. Harmless radioactive tags were attached to them. Then 
Geiger counters were placed near the nests and records of background 
radiation made. An increase in radiation indicated return of the birds 
(see Figures 2, 3A and 3B). 
Figure 4 shows Umiat relative to the Arctic Ocean and the Brooks 
Mountain Range. The plovers used for these experiments probably had 
reached Umiat by flying through one of the passes in this range of moun- 
tains, according to studies made by Dr. L. Irving and his associates. 
For this reason, we believe that the coast of the Arctic Ocean and a 
strip of territory between the ocean and Umiat had not been visited by 
these birds. When one plover was taken to point A, in the unknown ter- 
ritory (55 miles NE of Umiat on the Colville River) it required 14hours 
to return. Yet this same birdreturned inonly 5-1/2 hours when released 
at point C, a comparable distance away, at a point on the Anuktuvuk 
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