Migration of Birds (1950)Lincoln, Frederick Charles
Science
Migration of Birds (1950)
Lincoln, Frederick Charles
Birds; Birds -- Migration
The route taken by the white-winged scoters that winter on the
Atlantic coast already has been indicated (p. 59). Some birds of this
species, however, winter on the Pacific coast from Puget Sound south
to southern California. Their passage by thousands up and down the
coast has been noted as far north as northwestern British Columbia.
The species is known to nest in Alaska, which may be the home of
some, at least, of the scoters that winter on the Pacific coast. If
such be the case, however, it must be admitted that a part of the
route taken by the birds when on migration is unknown, though very
few observations are available from the interior of northern British
Columbia, across which the route may lie.
The southward route of those migratory land birds of the Pacific
coast that in winter leave the United States extends chiefly through
the interior of California to the mouth of the Colorado River and on
to winter quarters in western Mexico.
The movements of the western tanager show a migration route that is
in some ways remarkable. The species breeds in the mountains from
the northern part of Baja California and western Texas north to
northeastern British Columbia and southwestern Mackenzie. Its winter
range is in two discontinuous areas--southern Baja California and
eastern Mexico south to Guatemala (fig. 21). On the spring migration
the birds enter the United States about April 20, appearing first in
western Texas and the southern parts of New Mexico and Arizona (fig.
22). By April 30 the vanguard has advanced evenly to an approximate
east-and-west line across central New Mexico, Arizona, and southern
California. But by May 10 the easternmost birds have advanced only to
southern Colorado, while those in the far west have reached northern
Washington. Ten days later the northward advance of the species is
shown as a great curve, extending northeastward from Vancouver Island
to central Albert and thence southeastward to northern Colorado.
Since these tanagers do not reach northern Colorado until May 20,
it is evident that those present in Alberta on that date, instead
of traveling northward through the Rocky Mountains, which from the
location of their summer and winter homes would seem to be the
natural route, reached there by the Pacific coast route to southern
British Columbia and thence across the mountains, despite the fact
that these are still partly covered with snow at that time.
=Pacific oceanic route=
Public-domain text, read in full here on John Shaqi.
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