ALASKAN BIRD-LIFE 
General Characteristics 
The bird-population of Alaska is large, varied, and interesting, 
despite the remote and northern situation of the country. This is 
possible because it has a warm and moist summer, although a short 
one, favoring the rapid and copious growth of vegetation, including 
extensive forests; and because the adjoining seas abound in food 
naturally attractive to many kinds of birds. 
Any map of Alaska showing average weather conditions makes 
plain the fact that the lines (isotherms) which connect places in North 
America having the same average summer warmth swing up in the 
west far toward the north, proving—what is plain to all who live there 
—that a climate as mild in midsummer as that of the Great Lakes 
region prevails much farther toward the north on the Pacific than 
on the Atlantic slope of the continent. 
The amount and character of the bird-population in any region 
depend greatly on its having a climate favorable to birds at the season 
when they are hatching and rearing their nestlings, not only because 
most birds are creatures of mild rather than rough conditions, but 
because a warm and moist climate furnishes far more food, both ani¬ 
mal and vegetable, than does a cold or an arid one. The fact that 
a temperate summer climate extends as far northwest as central Alaska 
therefore allows the land-birds to spread their area of summer resi¬ 
dence much farther in that direction than they are able to do on the 
bleak northeastern side of the continent. For this reason Alaska has 
many kinds of birds well known in the United States. 
Another reason why Alaska has a large bird-population is found 
In the fact that the Pacific Coast and the long trough between the 
Rocky Mountains and the Sierras and northern coast ranges form 
natural and unobstructed pathways for the migratory birds of the west 
as they annually travel northward in spring and back again in autumn. 
Another convenient and natural approach for migratory birds is from 
western Canada down the upper Yukon Valley; and probably most of 
the small birds of the interior go and come by this river-valley 
route. When to this mingled company is added the group of birds—• 
principally sea-fowl—that reside in the Territory all the year round 
it is manifest that the bird-population of Alaska is not only extensive, 
but is more representative of the whole of North America than that 
of any other part of the continent. 
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