Beak of the Week – Tennessee Warbler

The Tennessee Warbler is one of the many species to pass through the Upper Texas Coast during spring migration. This warbler was named because the first cataloged specimen was collected in Tennessee, but that is only one of the many states this species frequents during migration. Migrating individuals can be spotted in all U.S. states east of Montana. In spite of this restrictive name, Tennessee Warblers overwinter in Central and South America and breed in northern Maine, Michigan, and throughout the boreal forests of Canada. Perhaps its Latin name, peregrina, from the Latin word for wanderer, is a more apt title.

Tennessee Warblers can be identified by their pointed bills, lack of wing bars, and white undertail coverts. Male individuals have a gray head, green back and wings, a dark line through the eye, and a white chin. Females are more olive overall but still have a faint eyeline and pointed bill. The most similar species, the Orange-crowned Warbler, is differentiated from the Tennessee by the Orange-crowned’s yellow undertail coverts and less distinct eyeline. Tennessee Warblers prefer to forage near the tops and middle of trees, gleaning insects from leaves in mixed flocks with other warblers and vireos.

Tennessee Warblers nest in regenerating mixed coniferous forests with open areas and dense shrubbery. Pairs make a cup-shaped nest near the ground in the roots of fallen trees or around clumps of sphagnum moss. The female lays between five and six eggs and incubates them for about 12 days. The male brings her food during this time and defends the territory from conspecifics (members of the same species). After hatching, both parents feed the young for 12 days, after which the young leave the nest. The quantity of spruce budworm caterpillars influences the success of nesting, with larger warbler populations irrupting after a good budworm season. Interestingly, despite their reliance on caterpillars in the spring and summer, in the winter, Tennessee Warblers add nectar to their diet, using their sharp bills to drain the nectar from tube-shaped flowers. The Tennessee Warbler is a species of least concern; its success is most likely due to its extensive overwintering range and broad use of habitats.

To find this species, scan mixed flocks of warblers and vireos near the tops of deciduous trees. The McGovern Canopy Walkway at Smith Oaks Sanctuary in High Island is also a great spot to see them up close. You may even find one foraging in the tree in your backyard!