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Status: Population size: 1.2 million Photo by Peter LaTourrette.

Lucy's Warbler
(Vermivora luciae)

A neotropical migrant that breeds in the southwestern United States and winters in western Mexico, Lucy's Warbler breeds in mesquite bosques, which are often remote. Habitat loss and to a lesser extent, Brown-headed Cowbird parasitism are creating problems for this species, whose populations have been locally extirpated from historical breeding grounds. This is the only warbler besides Prothonotary that nests in cavities.

Identification
The smallest North American wood-warbler, Lucy's Warbler measures only 4.25 inches in length. The adult spring male is gray and buffy below, with a tawny crown patch, rump, and uppertail coverts. Female is similar except she may lack a crown patch or have a much smaller one. The crown patch may not be visible in either sex in the field.

Distribution and Population Trends
Lucy's Warbler summers in riparian mesquite landscapes of Utah, Nevada, California, Arizona, New Mexico, and Texas. It winters in a narrow band along the Pacific slope in Mexico and its adjacent interior.

Populations are diminishing throughout breeding range due to loss of habitat. For example, this species was considered abundant in the San Xavier bosque region in the early 1900s, but today, the mesquite there has nearly all been removed, and few if any Lucy's Warblers nest there anymore.

Ecology
Birds leave the wintering grounds to arrive on breeding territory sometime in March or April. The female builds a nest in a cavity during April and May and incubates for about 12 days. The young leave the nest after roughly 11 days. Cowbird parasitism can negatively affects nest success.

This species uses natural cavities in mesquite and other trees as well as loose bark on cottonwoods and willows under which to nest. It may also use old woodpecker holes, but it has not been known to use artificial nest boxes. This strictly insectivorous bird dines mostly on caterpillars, beetles, and leafhoppers. Migratory dispersal begins in late June, continuing through early October.

Threats
The destruction of riparian mesquite is the biggest threat; overgrazing on mesquite scrub may also negatively affect the species, though more needs to be known about its use of this habitat. Brood parasitism is also a concern.

Conservation
One of the least known wood warblers in North America, this species could benefit from restoration of its mesquite/riparian habitat.

What Can You Do?
Audubon's Important Bird Area program is a vital tool for the conservation of Lucy's Warbler as well as other species. To learn more about the Important Bird Areas program and how you can help, visit: http://www.audubon.org/bird/iba/.

Support landscape management that maintains the species' breeding habitat.

If you own land that does support or has the potential for supporting Lucy's Warbler consider managing in ways that would increase numbers of the species. Contact your state wildlife agency or your state Audubon office for more details.

Volunteers are crucial to the success of programs that monitor the long-term status of wintering populations of Lucy's Warbler and other bird species. Audubon's Christmas Bird Count (CBC) is one of the longest-running citizen-science monitoring programs in the world and has helped to follow changes in the numbers and distribution of Lucy's Warbler. To learn more about the CBC and how you can participate, visit: http://www.audubon.org/bird/cbc.

Information on where Lucy's Warblers occur and in what numbers is vital to conserving the species. Help in monitoring this and other species by reporting your sightings to eBird. A project of Audubon and the Cornell Lab of Ornithology, eBird is the world's first comprehensive on-line bird monitoring program: http://www.audubon.org/bird/ebird/index.html.

References
Dunn, J. and K. Garrett. 1997. Peterson Field Guide: Warblers. Houghton Miffllin. New York.

Johnson, R.R., H.K. Yard, and B. T. Brown. 1997. Lucy's Warbler (Vermivora luciae). In The Birds of North America, No. 318 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D. C.

Cornell Lab of Ornithology. National Audubon Society. On line Warbler Watch. Lucy's Warbler. http://www.birdsource.org/warblers/index.html