The Black-throated Green Warbler occurs in a wide variety of forest habitats. They nest in conifer forests in the northwest of their range, mixed hardwoods forests in the southern Appalachians, and cypress swamps on the mid-Atlantic coast. Wintering birds are most common in the canopies of tall forests.Back to top
They eat almost exclusively insects during the breeding season, especially caterpillars, which they glean from small branches on both coniferous and deciduous trees. They also take berries in migration and feed on the buds of cecropia trees while wintering in the tropics.Back to top
The female chooses the nest site, which is usually 3-10 feet off the ground (sometimes much higher) in a small tree or sapling, and is located close to the trunk. The "Wayne's" subspecies often nests higher up and farther from the trunk, in a cypress, oak, or magnolia.
The nest is small and cup-shaped, made of twigs, bark, and spider silk and lined with hair, mosses, and feathers. Finished nests are 3–4 inches in diameter and about 2 inches tall. The female does most of the nest building, taking 4–8 days to complete the task.
|Clutch Size:||3-5 eggs|
|Number of Broods:||1 brood|
|Egg Length:||0.6-0.7 in (1.5-1.8 cm)|
|Egg Width:||0.5-0.5 in (1.2-1.3 cm)|
|Incubation Period:||12 days|
|Nestling Period:||8-11 days|
Whitish with variable brown blotches or speckles.
|Condition at Hatching:|
Helpless with sparse down.
Black-throated Green Warblers hop through arboreal vegetation, flying between trees but seldom above trees. The males are aggressive when on territory, attacking and chasing rivals. This is sometimes followed by the victor undertaking a shallow, mothlike flight. Males singing on territory often choose an exposed perch from which their yellow head will be conspicuous. Pairs are seasonally monogamous, remaining together until shortly after the young leave the nest. In fall migration this species often forms mixed-species flocks with other species of southbound warblers and resident songbirds. Black-throated Green Warblers also join mixed flocks of tropical species in winter.Back to top
Black-throated Green Warblers are common, and their populations held steady between 1970 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 9.2 million and assigns the species a Continental Concern Score of 9 out of 20, indicating a species of low conservation concern. The largest conservation issue for Black-throated Green Warblers is the degradation and loss of habitat. Despite its expansive breeding range, Black-throated Green Warblers are more commonly found in forest interiors than edges, so they’re susceptible to fragmentation. Invasive insects like woody adelgids have also caused the widespread death of conifers in some parts of the species’ range, leading to the disappearance of local populations in affected areas. Deforestation on the tropical wintering grounds decreases wintering habitat, although Black-throated Green Warblers will use native canopy trees on shade-grown coffee plantations or even on logged areas, provided that some emergent vegetation remains.Back to top
Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Morse, Douglass H. and Alan F. Poole. (2005). Black-throated Green Warbler (Setophaga virens), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. 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.