Dendroica petechia
yellow warbler

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. A highly migratory bird, Dendroica petechia winters in southern California, southern Florida, and south through the Brazilian Amazon, Bolivia, and Peru (Ehrlich 1992). (Ehrlich, Dobkin, and Wheye, 1992)

Dendroica petechia prefers moist habitats with high insect abundance. The presence of willows is one common feature of yellow warbler habitat north of Mexico. South of Mexico mangroves are a dominant feature. Habitats include the edges of marshes and swamps, willow-lined streams, and leafy bogs. Dendroica petechia also inhabits dry areas such as thickets, orchards, farmlands, forest edges, and suburban yards and gardens. They seem to prefer areas of scattered trees, dense shrubbery, and any other moist, shady areas (Nuttall and Chamberlin, 1971; USGS, 2000). (Celada et al., 1999; Nuttall, Chamberlin, and ed., 1903; U.S. Department of the Interior and U.S. Geological Survey, 2000)

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, Middleton, and ed., 1985; The Otter Side, 2000)

There is little information on causes of mortality. The longest known lifespan of a yellow warbler in the wild is 9 years, 11 months. (Celada et al., 1999; Klimkiewicz, 2002)

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, D. petechia is 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. (Perrins and Middleton et al. 1985; Rand 1971)

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 encounters. A "hiss" call has been described as being used in territorial defense. There are several calls used in the context of nest defense, including a "Seet" call that may be somewhat specialized for use in response to threats from parastic cowbids. 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.

Dendroica petechia is first and foremost an insect feeder but occasionally supplements the diet with some berries. By gleaning and hawking D. petechia forages for insects and spiders on the limbs of trees and bushes. Small insect larvae and caterpillars are preferred foods. (Ehrlich 1992; Nuttall 1903; USGS 2000)

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, D. petechia forages 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 songs (Ehrlich et.al., 1992). (Ehrlich, Dobkin, and Wheye, 1992)

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).