National Geographic Magazine/Volume 31/Number 4/Friends of Our Forests/Black-poll Warbler
The Warblers of North America
Range: Breeds in Hudsonian and Canadian Zones from limit of trees in northwestern Alaska, northern Mackenzie, central Keewatin, northern Ungava, and Newfoundland south to central British Columbia, Manitoba, Michigan, northern Maine, and mountains of Vermont and New Hampshire; winters from Guiana and Venezuela to Brazil.
The black-poll is one of our commonest warblers, in both spring and fall, and probably heads the warbler list in point of numbers. So far as superficial observations go, the bird would seem to be no spryer, no more industrious, and no more adept in hunting food than its compeers; but for some reason or other, possibly greater adaptability, it seems to have succeeded beyond most of its kind in extending its breeding range and in multiplying. It is a late migrant, both spring and fall, and when the hordes of black-polls put in an appearance, especially in the vernal season, one may know that the end of the migrating season is at hand. A laggard in spring, it is also a loiterer in fall, and occasionally a flock of black-polls will linger in some sheltered valley where food is abundant till long after others of the family have passed southward.
The bird nests chiefly in the far north, though it summers as far south as the Adirondacks. As it winters in South America, there are thus at least 5,000 miles between its extreme northern and southern habitats. Chapman notes that it is one of the very few warblers that migrate directly across the West Indies from South America to Florida. It makes its appearance in the Gulf States about the last of April. As pointed out by Professor Cooke, the black-poll is “one of the greatest travelers among the warblers. The shortest journey that any black-poll performs is 3,500 miles, while those that nest in Alaska have 7,000 miles to travel to their probable winter home in Brazil.” One can only wonder that so small a bird has the requisite courage and strength to undertake twice a year such a vast journey, every stage of which is compassed by dangers of one sort or another.