Distribution: The Lucy's warbler, Vermivora luciae, breeds in northern Mexico and in the southwestern deserts of the United States. It winters in western Mexico (Ehrlich et al. 1988). In Utah it occurs in the southern most portion of the state, associated with mesquite and desert habitats, but it can also be found in foothills in stream side cottonwoods and willows.
Ecology: The Lucy's warbler is one of the only two warblers in North America that breeds in cavities (Ehrlich et al. 1988; Stokes 1996; USDA 1991). Natural cavities (usually in mesquite) are used for nesting sites, as are abandoned woodpecker holes, loose bark, and deserted verdin nests (ibid.). The nest is generally 1.5 - 1.8 m (5 - 6 ft) above the ground but can range from 0.3 to 4.5 m (1 - 15 ft) above the ground (USDA 1991). Occasionally the Lucy's warbler nests in holes in banks, yuccas, willows, sycamores, and elderberries (Ehrlich et al. 1988; USDA 1991). The nest is made of coarse materials such as weeds, bark strips, and mesquite leaf stems and is lined with finer materials (Ehrlich et al. 1988). In Utah, sycamores and elderberries are used less frequently due to less availability.
Breeding ecology is largely unknown (Ehrlich et al. 1988; Stokes 1996). Eggs may be 3-7 (Stokes 1996) or 4-5 (Ehrlich et al. 1988) that are white to creamy with brown or red-brown spots. The pair is monogamous (ibid.). The Lucy's warbler is an early spring migrant that is active and flicks its tail frequently (Stokes 1996). It is occasionally a cowbird host (Ehrlich et al. 1988).
The diet of the Lucy's warbler consists of insects found on mesquite, shrubs, and desert vegetation (Stokes 1996). It forages for insects at the middle heights in mesquite, seldom foraging in the treetops or near the ground (USDA 1991).
Habitat Requirements: Habitat requirements for the Lucy's warbler are trees with cavities in which to build nests. Mesquite, cottonwood, or willow trees are needed for cavities, and act as substrates for verdin nests, which are subsequently used by Lucy's warblers.