BIRD OF THE WEEK: April 1, 2016
SCIENTIFIC NAME: Geothlypis formosa
POPULATION: 2.8 million
HABITAT: Breeds in deciduous forests with dense, moist understory; winters in humid tropical forest
Famed ornithologist Alexander Wilson discovered and named the Kentucky Warbler in 1811 during a birding expedition through that state. Another prominent ornithologist, Arthur Cleveland Bent, described this handsome species as “a lover of deep shade and dense, damp thickets.”
The Kentucky Warbler, like the Canada Warbler, Ovenbird, and Wood Thrush, depends on healthy forest with a rich and varied understory. When this habitat is cleared or fragmented, or the forest understory is lost due to browsing by over-abundant white-tailed deer, these birds become increasingly vulnerable to predation and cowbird parasitism.
During migration, the Kentucky Warbler is a frequent victim of window and tower collisions. It also faces habitat loss on its wintering grounds in addition to disappearing breeding habitat. The species is included on the 2014 State of the Birds Watch List, which notes species in need of significant conservation action.
Kentucky Warblers are bright yellow below, with distinctive broad black “sideburns” and crown combined with bold yellow “spectacles.” In spite of this, the birds can be hard to spot and are best identified by their song, a loud series of "chuuree" notes. They are best spotted in the shady forest interior as they forage through the leaf litter on long pink legs.
Like other North American warblers, this species feeds mainly on insects, including moths, bugs, ants, and grasshoppers. On their winter territory in the tropics, Kentucky Warblers sometimes accompany army ant swarms, picking up insects fleeing the ants. Interestingly, Kentucky Warblers defend small winter feeding territories.
Both male and female birds work to build the cup-shaped nest of dead leaves, grass, and bark strips. The nest is built on or near the ground at the base of a tree or shrub, usually well-hidden by overhanging vegetation. Other warblers, including the Black-and-white, Golden-winged, and Kirtland's Warblers, also nest close to or on the ground.
The female incubates the eggs and feeds the naked, helpless nestlings; when the young leave the nest 8-10 days after hatching, both sexes feed the fledglings. Young birds may leave the nest early if there is any threat of predation, such as free-roaming cats.
ABC has taken steps to conserve habitat for the Kentucky Warbler and many other neotropical migrants on both their breeding and wintering grounds, an approach called “full life-cycle” conservation. For example, we have supported Guatemalan partner FUNDAECO in creating or expanding several reserves where Kentucky Warblers and many other migratory birds winter, including Sierra Caral and Tapon Creek. In these areas, the Kentucky is one of the most commonly noted migrant warblers.
We're also working to reduce the number of Kentucky Warblers and other birds, such as Swainson's Thrush, that fall victim to glass windows—a threat that takes the lives of up to one billion birds in the United States each year. This is a preventable issue, and our nationwide efforts to prevent glass collisions are making a difference.
Now, after years of testing, we offer a range of tested, effective products for homeowners and architects on our Bird-Smart Glass page.