Blue-winged Warbler Life History

Habitat

Blue-winged Warblers breed in shrublands, scrubby areas, thickets, and forest edges. During migration they rest and forage in open woodlands, shrublands, thorn forests, gardens, and parks. On the wintering grounds they frequent evergreen and tropical deciduous forest and edge, scrubby areas, and hedgerows; often associating with mixed-species flocks.

Food

Blue-winged Warblers eat caterpillars, crickets, grasshoppers, spiders, flies, ants, and beetles, which they often pick from clusters of dead leaves while dangling upside down in chickadee-like fashion.

Nesting

Nest Placement

Females select a spot on or near the ground to build a nest near the boundary between forest and scrub. Females frequently place the nest at the base of goldenrods, berry shrubs, or clumps of grasses or sedges.

Nest Description

Females build an open cup nest of grasses, bark shreds, and dead leaves, which she lines with finer plant material. Nest building takes 2–4 days on average.

Nesting Facts

Behavior

Blue-winged Warblers move with quick flights and short hops through scrubby vegetation. They tend to forage at the tips of branches often hanging upside down to pick insects from leaves. Males begin establishing territories shortly after arriving on the breeding grounds, but they don't tend to return to the same breeding areas in successive years. Intruding males are met with aggressive posturing, tail spreading, harsh chipping, and chasing. Once females arrive, males chase them around, and the females may chip in response. Courting birds may raise their crowns, flick and spread their tails, and chase each other around, sometimes locking bills. Pairs are thought to be monogamous, but like other warblers, they likely take part in extrapair copulations. Blue-winged Warbler nests are commonly parasitized by Brown-headed Cowbirds, which lay their eggs in warblers' nests. The warbler then unwittingly ends up raising a cowbird chick, most often at the expense of her own chicks.

Conservation

Blue-winged Warblers are fairly common, but between 1966 and 2019, their populations declined approximately 0.7% a year for a cumulative decline of about 30%, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population is 680,000 and rates them 13 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. In the late 1800s, Blue-winged Warbler populations expanded northward as agricultural fields were abandoned and forest clearcuts started regrowing. This northward expansion increased the frequency of contact and hybridization with Golden-winged Warblers; a Partners in Flight Red Watch List species for birds with restricted distributions and small, declining populations. Hybridization and competition between Golden-winged and Blue-winged Warblers is partially responsible for declining populations of Golden-winged Warblers. Although Blue-winged Warblers have expanded their range northward, suburban developments are reducing the amount of second growth and scrub habitat in some locations, which may be responsible for local declines in Blue-winged Warblers.

Credits

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Gill, Frank B., Ronald A. Canterbury and John L. Confer. (2001). Blue-winged Warbler (Vermivora cyanoptera), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2021.1. Patuxent Wildlife Research Center, Bird Banding Laboratory 2021.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Pieplow, N. (2017). Peterson Field Guide to Bird Sounds of Eastern North America. Houghton Mifflin Harcourt Publishing Company, NY, USA.

Rosenberg, K. V., J. A. Kennedy, R. Dettmers, R. P. Ford, D. Reynolds, J. D. Alexander, C. J. Beardmore, P. J. Blancher, R. E. Bogart, G. S. Butcher, A. F. Camfield, A. Couturier, D. W. Demarest, W. E. Easton, J. J. Giocomo, R. H. Keller, A. E. Mini, A. O. Panjabi, D. N. Pashley, T. D. Rich, J. M. Ruth, H. Stabins, J. Stanton, and T. Will (2016). Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee.

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.

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