214 
THE CONDOR 
Vol. XVII 
to the Arctic coast of Alaska. The earliest birds were noted at Point Barrow 
May 15, 1882, and May 25, 1883. But already by this date the species has 
appeared on the Mackenzie near the mouth of the Liard. By what route do 
these birds reach their destination? They do not come from the south, for the 
species is unknown in southern Canada at any time of the year. The nearest 
part of the Pacific Ocean is to the southwest near Sitka, but the birds- do not 
come by that route, for the birds of this part of the country have been closely 
watched for several years, and the only spring record of the Yellow-billed Loon 
is that of a straggler seen on Admiralty Island May 25, 1911. 
They do not come up the valley of the Yukon, for this species is not known 
anywhere in the interior of Alaska. The only possibility left is that they come 
from the Arctic Ocean to the northward. But all the lakes between Great Slave 
Lake and the Arctic Ocean are still covered with ice and so is the delta of the 
Mackenzie River. Thus apparently the only solution of the problem is a migra- 
tion at a single flight from the open waters of the Arctic Ocean across 700 miles 
of frozen country to the open water near Great Slave Lake. This supposition 
also requires that the birds pass Point Barrow off-shore many days before they 
were noted at that place. Thus the spring route from eastern Asia would be first 
a 2000 mile trip northeast to Bering Strait, then 500 miles still northeast to 
round Point Barrow, then 500 miles east to the coast of Mackenzie, and then 
finally 700 miles south — in the spring — to Great Slave Lake. Truly a most 
remarkable route, but who will suggest a route more plausible? 
The route is apparently reversed in the fall. The species is common on 
Great Slave Lake until the middle of September, and Sir John Franklin says 
that near there at Fort Enterprise this species was the last water bird to leave, 
October 26, 1820. By this time the smaller lakes and streams were closed by the 
ice, but there would still remain enough open water in the larger lakes and 
the Mackenzie River for the birds to work their way north in the early winter 
the 700 miles to the open Polar Sea. Then there would still remain a 3000 
mile trip to their winter home and they would be passing Point Barrow in 
November weeks after the last of the birds which nested there had disappeared, 
for the latest fall date at this place is September 25, 1897. And so this article 
closes with a reiteration of the opening paragraph : The migration route of the 
Yellow-billed Loons which visit Great Slave Lake is the most incomprehensible 
problem of migration on the North American continent. 
Washington, D. C., August 18, 1915. 
NOTES ON THE NESTING OF THE WHITE-TAILED PTARMIGAN 
IN COLORADO 
By W. C. BRADBURY 
WITH FIVE PHOTOS 
O N MAY 7th of this year (1915) I sent out a party of four young men, 
with team, camera, camping outfit and equipment, for the purpose of col- 
lecting the rarer varieties of eggs and birds nesting at high altitudes, this 
in the interests of the Colorado Museum of Natural History, Denver. Com- 
mencing at the foot-hills near Morrison, Colorado (altitude 5750 feet above sea- 
