66 NORTH AMERICAN DUCKS, GEESE, AND SWANS. 
they migrate by the most direct route. Though occurring accidentally 
io northern Europe and found on the Arctic coast of northeastern 
Asia, sometimes in considerable numbers, the lesser snow goose is not, 
as yet. known to breed in the Eastern Hemisphere. 
Winter range.— Both forms of the snow goose occur during the 
winter season in the lower Mississippi Valley. It seems probable that 
in this district the Mississippi River is the approximate dividing line 
between the two forms, to the westward C. hyperborea being the more 
common, to the eastward, ( '. nivalis. Both forms winter as far north as 
southern Illinois, and the lesser snow goose is abundant in winter in 
Louisiana and Texas, and ranges south in Mexico to Guanajuato and 
Jalisco, and rarely to northern Lower California. It winters spar- 
ingly in southern Colorado, more commonly in Utah, abundantly in 
Nevada, and along the Pacific coast from southern California (Orange 
County) to southern British Columbia. On the Asiatic side it winters 
south to Japan. 
Spring migration. — Writing many years ago, Ross states that the 
lesser snow goose arrives at Great Slave Lake earlier than the greater. 
Recent records of spring migration confirm this statement, and our 
present knowledge of isothermal lines affords a satisfactory explana- 
tion. It is considered that the common species in eastern North 
Dakota is C. nivalis, while the bird of Montana is C. hyperborea. 
Long-continued observations in the valley of the Red River of the 
North indicate that the first C. nivalis arrive on the average at lati- 
tude 47° on April 15; at the same latitude in central Montana the first 
migrants of O. hyperborea appear April 6. The more eastern birds 
advance to Aweme, Manitoba, latitude 50°, April 22, while at this 
latter date the van has reached Edmonton, Alberta, latitude 54°. Yet 
these 4 more western and northern birds (lesser snow geese) are actually 
traveling in warmer weather than their eastern relations migrating at 
a later date; for during the last third of April the temperature at 
Edmonton averages about 2 degrees warmer than at Aweme. 
Further advance of the lesser snow goose is recorded during the 
spring of 11*04 to Fort Vermilion, latitude 58°, April 26, and to Fort 
Simpson, latitude 62 . May 2. Last of Fort Simpson at Southampton 
[sland, in Hudson Hay, this same spring the first snow geese were not 
seen until thirty-three days later dune 4 while to the westward, at 
Point Barrow, Alaska, more than 500 miles farther north, the first 
Lesser snow geese arrive just about the same time as at Fort Simpson. 
The lesser snow geese that reach their breeding grounds by way of 
Alaska probably winter at least 800 miles farther north than those 
of the Mississippi Valley, and spring opens on the Pacific coast much 
earlier than in the interior. 
The most northern records of the lesser snow goose are on Banks 
Land, where itarrived at Princess Royal Islands. Latitude T-') , May 31, 
