Yellow warblers are easily recognized. They are the most extensively yellow of warblers, with golden yellow plumage and rusty streaks on the breast. Yellow warbler males and females are similar with golden yellow upper parts tinged with olive, yellow under parts, and thin pointed beaks. Males are generally brighter, especially during the breeding season. Yellow warblers reach an average size of 10 to 18 cm in length (Perrins and Middleton 1985; The Otter Side 2000). (Perrins and Middleton, ed., 1985; The Otter Side, 2000)
Yellow warblers spend the majority of the year throughout much of North America, including Alaska, northern Canada, and the northern 2/3 of the United States. Highly migratory birds, yellow warblers spend the winter in southern California, southern Florida, and as far south as Peru (Ehrlich 1992). (Ehrlich, et al., 1992)
Yellow warblers prefer moist habitats because they offer a large variety of insects. These habitats include the edges of marshes and swamps, willow-lined streams, and leafy bogs. Yellow warblers also inhabit dry areas such as thickets, orchards, farmlands, forest edges, and suburban yards and gardens. They prefer areas of scattered trees, dense shrubbery and any other moist, shady areas.
From their wintering grounds, yellow warblers arrive in the northern areas with little time between migrations for the reproduction process, which at a minimum takes 45 days. The process begins with a fairly elaborate courtship performed by the male who may sing up to 3,240 songs in a day to attract a mate. Yellow warblers are primarily monogamous, but there are occasional polygynous matings. Although yellow warblers are generally single-brooded, if their first nesting attempt fails they will breed again. (Perrins and Middleton et al. 1985; Rand et al. 1971) (Celada, et al., 1999)
Yellow warblers usually breed in late May and early June. Females lay 4 to 5 eggs, incubation lasts 10 to 14 days, nestling period lasts from 8 to 12 days, and parental feeding may extend to two weeks after the young leave the nest, sometimes longer. Females and males first attempt to breed in their first year after hatching. (Celada, et al., 1999)
Both male and female parents participate in feeding the young, usually providing them with different kinds of insect larvae. The responsibility of incubation, construction of the nest, and most feeding of the young lies with the female, while the male contributes more as the young develop. After they mature, some of the fledglings may follow the mother while the rest remain with the father.
Yellow warblers are songbirds, both males and females engage in distinct musical songs. During the breeding season, yellow warblers are extremely territorial, but rejoin small flocks after breeding. Because of their well-built open-cup tree nests, parasitic cowbirds will often lay eggs in yellow warbler nests. However, yellow warblers are not always fooled and will cover the intruder's eggs with an additional layer of nesting materials, sometimes burying its own. Yellow warblers are active during the day.
Yellow warblers are migratory birds that breed throughout much of North America and winter primarily from Mexico to northern South America. (Celada, et al., 1999)
Yellow warbler calls include notes given by young begging for food, by birds responding to the presence of predators, and in diverse social situations. A "hiss" call has been described as being used in territorial defense. There are several calls used in the context of nest defense. These include a "Seet" call that may be somewhat specialized for use in response to threats from cowbids attempting to lay their eggs in the warbler's nest. Singing behavior is used for male-female communication, both for mate attraction and for interactions between mates. Songs are sung primarily by males. Females often give simple, high frequency "chip" calls at the end of a male song. No nonvocal sounds are thought to be used in communication. (Celada, et al., 1999)
Yellow warblers also communicate with postures and perhaps with touch. Yellow warblers perceive their environment with their keen vision, hearing, touch, and limited chemical sensation.
Yellow warblers mostly eat insects but will occasionally also eat some berries. They forage for insects and spiders on the limbs of trees and bushes. Small insect larvae and caterpillars are preferred foods.
There is little information on the response of yellow warblers to predators. They have twice been observed to join other bird species in mobbing (attacking, as a group) great horned owls. Females will respond to snakes with distraction displays or give agitated vocalizations.
Yellow warblers are preyed on by a wide variety of small predators, which primarily prey on eggs and young in the nest. Adults and fledged juveniles may be taken by small birds of prey, such as American kestrels and Cooper's hawks. (Celada, et al., 1999)
Brown-headed Cowbirds and Shiny Cowbirds will lay their eggs in yellow warblers' nests. As a result the nest may be abandonned or covered over with a new lining, which can involve the loss of warbler eggs. Sometimes, however, warbler young do survive along with the cowbird young.
Yellow warblers are important predators of insects, especially potential pest species, in the ecosystems in which they live. They may help to disperse fruit seeds when they eat fruit.
There are no known negative effects of yellow warblers on humans.
Primarily an insectivore, yellow warblers forage for food in suburban areas, ridding farms and gardens of unwanted insect pests. Additionally, yellow warblers are popular with birders, they have lovely golden yellow plumage and musical song.
Dendroica petechia is common, but due to loss of riparian woodland habitat and extensive paratism by cowbirds there has been a decline in yellow warbler populations. An increase in population occurs in areas where grazing and herbicide are restricted, permitting regrowth of riparian vegetation. One subspecies, the Barbados Yellow Warbler, D. petechia petechia, is on the U.S. endangered species list (Ehrlich et al. 1992; IUCN 2000; CITES 2000; USFW 2001).
Tanya Dewey (editor), Animal Diversity Web.
Kathleen Bachynski (author), University of Michigan-Ann Arbor.
Matt Kadlec (author), University of California, Irvine, Rudi Berkelhamer (editor), University of California, Irvine.
Celada, C., P. Lowther, N. Klein, C. Rimmer, D. Spector. 1999. Yellow Warber (Dedroica Petechia). The Birds of North America, No. 454.
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Perrins, C., L. Middleton, ed.. 1985. The Encyclopedia of Birds. London, Sydney: George Allen & Unwin.
Rand, A. 1971. Birds of North America. New York: Doubleday & Company, Inc..
The Otter Side, 2000. "Yellow Warbler (Dendroica petechia)" (On-line). Accessed October 24, 2000 at http://www.otterside.com/htmfiles/wrbye-h.htm.
U.S. Department of the Interior, U.S. Geological Survey, 2000. "Yellow Warbler Dendroica Petechia" (On-line). Accessed October 25, 2000 at http://www.mbr.nbs.gov/id/framlst/i6520id.html.
U.S. Fish and Wildlife Service, 2001. "Division of Endangered Species, Species Information" (On-line). Accessed 12 March 2001 at http://endangered.fws.gov/wildlife.html.
U.S. Fish and Wildlife Services, 2000. "U.S. Fish and Wildlilfe Services, International Affairs, CITES" (On-line). Accessed October 30, 2000 at http://international.fws.gov/pdf/citesoma.pdf.