took the Audubon for the
myrtle. The former has a yellow throat, while the latter's throat is
white.

In all the upper mountain valleys, and on the steep slopes of the
western as well as the eastern side of the Divide, I had the Audubon
warblers often at my elbow. In summer they make their homes at an
altitude of seven to eleven thousand feet, and are partial to pine
timber; indeed, I think I never found them elsewhere, save occasionally
among the quaking asps. I learned to distinguish Audubon's chanson from
those of his fellow-minstrels. It is not much of a song--a rather weak
little trill, with a kind of drawl in the vocalization that forms its
diagnostic feature. The persistency with which it is repeated on the
solitary pine-clad mountain sides constitutes its principal charm.

The winter haunts of Audubon's warblers are farther south than Colorado,
mostly in Mexico and Guatemala, although a few of them remain in the
sheltered mountain valleys of the western part of the United States.
Early in May they appear on the plains of eastern Colorado, where they
are known only as migrants. Here a double movement presently takes
place--what might be called a longitudinal and a vertical migration--one
division of the warbler army sweeping north to their breeding grounds in
Canada, and the other wheeling westward and ascending to the alpine
heights among the mountains, where they find the subartic conditions
that are congenial to their natures without travelling so great a
distance. Here they build their nests in the pine or spruce trees, rear
their families, and as autumn approaches, descend to the plains, tarry
there a week or two, then hie to their winter homes in the South.

One of the most gorgeous tenants of this valley was Wilson's warbler.[3]
It wears a dainty little cap that is jet black, bordered in front and
below with golden yellow, while the upper parts are rich olive and the
lower parts bright yellow. These warblers were quite abundant, and were
evidently partial to the thickets covering the boggy portions of the
vale. While Audubon's warblers kept themselves for the most part among
the pines on the slopes and acclivities, the little black-caps preferred
the lower ground. Their songs were not brilliant performances, though
rather pleasing, being short, jerky trills, somewhat lower in the scale
than those of the well-known summer warbler.

[3] Mr. Aiken says, "The Rocky Mountain representative of Wilson's