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Mourning Warbler

(Oporornis philadelphia)
Banded Spring, 2004
Carmel, Indiana

General Information

The Mourning Warbler is a long distance migrant from southern Central America and northern South America. It breeds in northern North America including the Great Lakes region, and at higher altitudes in the Appalachian Mountains south to West Virginia.

It is fairly common, and forms a superspecies with the very similar MacGillivray’s Warbler that occurs in the Western US. Separation of the Mourning and MacGillivray’s warbles in the field can be one of the most difficult warbler identification problems. Although the Mourning Warbler lacks the bold eye ring of the Connecticut Warbler, the similar grayish hood of the Connecticut Warbler can also cause confusion in the field.

One wonders how this species came by the somewhat melancholy name “Mourning.” Alexander Wilson (1766-1813), author and artist for American Ornithology, came upon this species in a marsh near Philadelphia, and in 1810, because the black markings on its breast reminded him of someone in mourning, suggested the name Mourning Warbler.


The adult male has a dark gray hood with extensive black mottling on the breast. The upper parts are olive green. The under parts are bright yellow with a slight olive wash on the sides. These birds are from 5 to 5.75 inches long. Weights range from 9.7 to 13.2 grams.

Mourning Warbler - Adult Male
Figure 1 - Mourning Warbler - Adult Male

Mourning Warbler - Adult Male
Figure 2 - Mourning Warbler - Adult Male

There are no eye crescents such as those found on the MacGillivray’s Warbler. Immatures and adult females, however, show whitish eye arcs (see Fig. 8 below).

This attractive warbler is a skulking bird of dense undergrowth. During the breeding season, it favors young secondary growth forest edges, and clearings with dense under story. During spring migration, it follows the coast of the Gulf of Mexico rather than flying across the Gulf. It is, along with the Connecticut Warbler, the latest spring warbler to pass through on its way to its breeding grounds.

Mourning Warbler - Adult Male
Figure 3 - Mourning Warbler - Adult Male

Mourning Warbler upper wing
Figure 4 - Mourning Warbler upper wing

The upper parts are olive green.

The under wing is more whitish, but the undersides of the body are bright yellow.

Mourning Warbler under wing
Figure 5 - Mourning Warbler under wing

Mourning Warbler upper tail
Figure 6 - Mourning Warbler upper tail

The upper tail is also olive green.

The long bright yellow under tail coverts extend well down the tail.

Mourning Warbler under tail pattern
Figure 7 - Mourning Warbler under tail pattern

Immature Mourning Warbler
Figure 8 - Immature Mourning Warbler

Note the whitish eye crescents on this immature Mourning Warbler. The first year male is similar in appearance to the first year non-breeding female. It has an olive-brown hood, and a buffy throat with a yellow wash that breaks through the hood in the center of the breast. The immature male also has some indistinct black mottling on the sides of the breast.

Nesting Behavior

The cup nest, built by both sexes of dead leaves, grasses, and weed stems, is placed on or near the ground in a thicket where heavy undergrowth occurs as on the edges of a swamp, secondary growth or a brushy thicket. Three to five eggs, incubated by the female, hatch in 12 to 13 days. The young, tended by both parents, leave the nest in 7 to 9 days, but are not able to fly until the second week out of the nest.

Banding Recoveries

According to the web page of the Bird Banding Lab, a total of 32,398 Mourning Warblers were banded between 1955 and 2000. Of these, only 24 have been encountered away from the area where they were banded.

If you should recover a banded bird, you can report the band number to the Bird Banding Lab by calling 1-800-327-BAND.

Economic Importance & Conservation Status

This species consumes insects and spiders, and no doubt contributes to the ecological control of insect pest species. The nests of this species are rarely parasitized by Brown-headed Cowbirds, which is fortunate since forest clearing has enabled Brown-headed Cowbirds to expand their range and parasitize so many species once protected by the vast forests of North America. Populations of this species appear to be stable. Because this species prefers secondary growth and brushy habitats, forest clearing has probably favored this species, and numbers may be higher than those prior to the 1700’s.

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