Tennessee Warbler Life History

Habitat

Habitat Forests

Tennessee Warblers breed in boreal forests of coniferous or mixed deciduous-coniferous trees. These are often younger or middle-aged woodlands regenerating from a disturbance, featuring open areas and dense shrubs. In the winter, they can be found in the tropics in open to semiopen broadleaf forests. They take especially well to cultivated citrus orchards and shade-grown coffee plantations. In some areas, shade coffee plantations may be critical habitat during the dry season. In migration they are not picky, and can be found in many types of wooded habitats in eastern North America.

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Food

Food Insects

Tennessee Warblers eat mostly caterpillars and other invertebrates, gleaning or plucking them from the outer foliage of trees and shrubs. Spruce budworms are a key prey species; these insects periodically form immense outbreaks providing an abundant food resource that lasts for several years before fading away. During summer, caterpillars sometimes form up to 90% of the food brought to young. Other prey items include beetles, spiders, bees, wasps, and flies. In fall and winter they also feed on fruit when it is available. Their winter diet also includes nectar, which they take by piercing the bases of tube-shaped flowers with their sharp bills (this approach means that they do not aid the flowers in pollination).

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Nesting

Nest Placement

Nest Ground

Nests are extremely well concealed near the ground, often in a hummock of sphagnum moss or in the roots of a fallen tree.

Nest Description

Makes a cup-shaped nest of two layers. The outer layer consists of dead grass or weed stems, and the inner layer is lined with fine grasses and occasionally hair or mosses.

Nesting Facts

Clutch Size:5-6 eggs
Number of Broods:1 brood
Egg Length:0.6-0.7 in (1.4-1.7 cm)
Egg Width:0.4-0.5 in (1.1-1.3 cm)
Incubation Period:11-12 days
Nestling Period:11-12 days
Egg Description:White, speckled with reddish brown.
Condition at Hatching:Helpless.
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Behavior

Behavior Foliage Gleaner

The Tennessee Warbler is a small and active warbler that hops and flits through the upper forest canopy seeking invertebrates from the tips and surfaces of leaves. Breeding males aggressively defend their territories from other males, singing from perches in the upper two-thirds of trees. Pairs are seasonally monogamous, with no known extra-pair copulation. Female Tennessee Warblers incubate the eggs, with males feeding females during this period. Both sexes feed the nestlings upon hatching. On migration and in winter, Tennessee Warblers often form foraging flocks with other species. During the nonbreeding season they are generally gregarious and tolerant both of other Tennessee Warblers and other species, although they can be aggressive in defending nectar sources.

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Conservation

Conservation Low Concern

The Tennessee Warbler's remote northern breeding range makes population trends difficult to estimate. Their numbers appear to have remained stable or slightly declined between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 110 million, and the species rates a 10 out of 20 on the Continental Concern Score, indicating a species of low concern. Populations can fluctuate widely over the course of several years, as spruce budworm outbreaks grow and recede. Their rather extensive wintering range and broad use of habitats may make Tennessee Warbler less vulnerable to decline than species with narrower distributions and more specific habitat needs.

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Credits

Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Rimmer, Christopher C. and Kent P. McFarland. (2012). Tennessee Warbler (Oreothlypis peregrina), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Stephenson, T. and S. Whittle (2013). The Warbler Guide. Princeton University Press, New Jersey, USA.

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