64 CIRCULAR 363, U. 8S. DEPARTMENT OF AGRICULTURE 
River, in southwestern Mackenzie. This coincides with the time that 
first arrivals are noted fully 700 miles north, at Point Barrow, Alaska. 
The problem has been to ascertain the route used by these birds 
to their principal nesting grounds in the interior. 
For a long time it was believed that this big diver did not winter in 
large numbers anywhere on the Pacific coast, and it had been supposed 
that the spring route extended 2,000 miles northeastward from a 
wintering ground somewhere in eastern Asia to Bering Strait, then 
500 miles still northeast to round Point Barrow, then 500 miles east 
to the coast of Mac- 
kenzie, and finally 
700 miles south—in 
spring—to the region 
near the eastern end of 
Great Slave Lake. 
The  yellow-billed 
loon is a powerful flier, 
and itis probable that 
this suggested route 
is correct for those 
birds that breed in the 
northern coastal re- 
gions. A reasonable 
doubt may be enter- 
tained, however, 
whether the breeding 
birds of Great Slave 
Lake and contiguous 
areas reach their 
breeding grounds by 
the 700-mile flight 
south from the Arctic 
coast. Within recent 
years it has been 
found that these 
birds are fairly com- 
mon in the maze of 
channels and islands 
off the coast of 
southeastern Alaska 
+ as late as the last 
ea Bam 2 ot October atid jan 
"Griliwicleneach ‘year im the ouse ares up nacas eal be pe te DE ayes gael ies 
different routes or, at least, does not make the same stops, while they are present there 
on migration. 2 : 
during the period from 
November through January also, or they may at that time move 
farther offshore and so escape detection. If this region is an impor- 
tant wintering ground, as seems probable, then it is likely that the 
breeding birds of the interior reach their nesting grounds by a flight 
eastward across the mountains, a trip that is well within their flying 
ability, rather than by a circuitous route around the northern coast. 
The air-line distance from southeastern Alaska to the mouth of the 
Liard River is in fact less than the distance to that point from the 
mouth of the Mackenzie. 
