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Prothonotary Warbler

Protonotaria citrea ORDER: PASSERIFORMES FAMILY: PARULIDAE

IUCN Conservation Status: Least Concern

The brilliant Prothonotary Warbler bounces along branches like a golden flashlight in the dim understory of swampy woodlands. This golden ray of light is unique among warblers with its beady black eye and blue-gray wings. It is also one of two warblers that build their nests in holes in standing dead trees. Often called a "swamp warbler" in the southeast, it also occurs surprisingly far to the north along rivers. Its population is declining, due to loss of forested wetlands in the U.S. and mangroves on its wintering grounds.

At a GlanceHelp

Measurements
Both Sexes
Relative Size
Larger than a Carolina Chickadee, smaller than a Song Sparrow.
Other Names
  • Paruline orangée (French)
  • Chipe dorado, Reinita Calecidorada (Spanish)

Cool Facts

  • Most warblers nest either on the ground, in shrubs, or in trees, but the Prothonotary Warbler and the Lucy's Warbler build their nests in holes in standing dead trees. They may also use nest boxes when available.
  • The Prothonotary Warbler got its name from the bright yellow robes worn by papal clerks, known as prothonotaries, in the Roman Catholic church.
  • The Prothonotary Warbler had its day in court during the Cold War. In 1948 Alger Hiss an American government official was accused of being a soviet spy. Part of the trial hinged on whether Hiss knew Whittaker Chambers, a former member of the U.S. Communist Party. Chambers claimed that he talked to Hiss about watching birds and reported Hiss's excitement about seeing a Prothonotary Warbler on the Potomac River. This bird sighting linked the two people and eventually led to Hiss's sentence and to the rise of Richard Nixon to political power.
  • For Prothonotary Warblers it pays to be bright. Males that are brighter yellow gain access to better nest sites than less colorful males, according to a study conducted in Louisiana.
  • The oldest recorded Prothonotary Warbler was a male, and at least 8 years, 1 month old when he was identified by his band in Ontario in 2005. He had been banded in the same area in 1999.

Habitat


Forest

Prothonotary Warblers breed in flooded bottomland forests, wooded swamps, and forests near lakes and streams. They tend to avoid forest patches smaller than about 250 acres or forest borders less than 100 feet wide. During migration they stop in coastal areas, marshes, citrus groves, and scrub to refuel. During the winter, they are most common in mangrove swamps, but they also use tropical dry forest and wooded areas near streams.

Food


Insects

Prothonotary Warblers eat spiders, butterflies, moths, beetles, flies, caterpillars, mayflies, midges, grasshoppers, ants, and leafhoppers. They also eat snails and mollusks. During the nonbreeding season they eat fruit and seeds in addition to insects.

Nesting

Nesting Facts
Clutch Size
3–7 eggs
Number of Broods
1-3 broods
Egg Length
0.7–0.7 in
1.8–1.9 cm
Egg Width
0.6–0.6 in
1.4–1.5 cm
Incubation Period
12–14 days
Nestling Period
9–10 days
Egg Description
White spotted with rust-brown to lavender.
Condition at Hatching
Helpless, eyes closed, with minimal down.
Nest Description

The male places moss inside the hole prior to attracting a mate, but the female builds the remainder of the nest with rootlets, plant down, grape plants, or cypress bark. She lines the cup-shaped nest with grasses, sedges, rootlets, old leaves, and poison ivy tendrils. It takes the female 3–8 days to build a nest. The entrance hole to the nest cavity is around 2 inches across. The nest cup is about 2 inches wide.

Nest Placement

Cavity

The Prothonotary Warbler places its nest in holes created by woodpeckers and chickadees, in natural holes in standing dead trees, and in nest boxes. The male selects several nesting sites throughout his territory, but the female ultimately selects which one to use. Nests are often near or over standing water in bald cypress, willows, cypress knees, and sweetgum trees. Nest height ranges from about 2–33 feet above the ground, depending on availability of nesting holes.

Behavior


Foliage Gleaner

Prothonotary Warblers forage in the understory, slowly hopping along branches, twigs, and on the ground in search of food. Sometimes they climb up tree trunks and pick insects off the bark similar to the way a Black-and-White Warbler forages. When the male establishes his territory he searches for potential nesting sites in standing dead trees and places a layer of moss in each hole. He selects a few good spots and displays in front of each site for the female. He flies slowly up above the tree canopy with tail spread and slowly flutters back down. To entice the female to check out potential nesting sites, he enters and exits the hole several times. As soon as the female selects a site, she starts building a nest. On the breeding grounds males and females aggressively defend their territories, chasing away intruders with snaps of their bills and sometimes with physical attacks. They are monogamous and maintain their bonds during the breeding season. Occasionally they stay with the same mate the following season. They also tend to return to the same breeding site in subsequent years, especially if they successfully raised offspring at that site. Raccoons and snakes are frequent nest predators. Brown-headed Cowbirds also affect nest success. Cowbirds lay their eggs in the nests of Prothonotary Warblers, forcing the warblers to raise cowbird young at the expense of their own. They are not territorial on the wintering grounds and in some locations they make short-distance movements to take advantage of seasonal resources. Groups of Prothonotary Warblers forage together on the wintering grounds and they also join mixed feeding flocks.

Conservation

status via IUCN

Least Concern

Prothonotary Warblers are uncommon to fairly common in good habitat. Their populations declined over 1% per year from 1966–2015, resulting in a cumulative loss of 42% over that period, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 1.6 million, with 100% of the population spending at least part of the year in the United States, and 26% wintering in Mexico. There are some reports of the species breeding in southern Canada, and many birds winter farther south in Central and South America. The species rates a 14 out of 20 on the Continental Concern Score and is on the 2016 State of North America's Birds' Watch List, which includes bird species that are most at risk of extinction without significant conservation actions to reverse declines and reduce threats. As habitat specialists, these warblers are vulnerable to the loss and alteration of forested wetlands on their breeding grounds. Removal of standing dead trees and channeling of streams can affect availability of nest sites as well as nest success. Nests above standing water greater than 11 inches deep were less likely to be depredated by raccoons than those in shallower areas. Prothonotary Warblers are also vulnerable to the loss of mangroves on their wintering grounds along the coast of Mexico and Central and South America due to coastal development and aquaculture. Installation of nest boxes with predator guards and restoration of natural flood regimes to forested wetlands on the breeding grounds have been successful at increasing local populations.

Credits

Range Map Help

Prothonotary Warbler Range Map
View dynamic map of eBird sightings

Migration

Medium to Long-distance migrant. Migrates across the Gulf of Mexico to Mexico where it follows the Atlantic slope south.

Backyard Tips

If you live in the Southeast near forested wetlands or water a nest box may attract a breeding pair. Attach a guard to keep predators from raiding eggs and young. Find out more about nest boxes on our All About Birdhouses site, including plans for building a nest box of the appropriate size for a Prothonotary Warbler.

Find This Bird

Finding a Prothonotary Warbler means finding the right habitat. They’re most numerous in the Southeast, where you may find them in swamps and bottomland forests. But they also use forests along rivers such as the Mississippi, so they occur farther north than you might expect in Wisconsin and all the way north to New Hampshire along other rivers. Once you find the right spot, head towards water and start looking for a bright yellow bird in the understory. They tend to stay low in the forest and often forage above water and along shorelines. These bright yellow birds are conspicuous, and their loud ringing song can help guide you to them even before you see them. The best times to look for them in the U.S. are from April–July.

You Might Also Like

Watch patterns of Prothonotary Warbler migration on an animated eBird Occurrence Map: Prothonotary Warbler

Learn more about standing dead trees: Snags: Nature's Apartment Complexes, Habitat Network, January 18, 2012.

How To Listen To Bird Song—Tips And Examples From The Warbler Guide, All About Birds, May 1, 2015.

In Colombia, Shade-Grown Coffee Sustains Songbirds And People Alike, Living Bird, Autumn 2016.

People Power And Sustainable Forestry Keep Deforestation At Bay In Guatemala, Living Bird, Autumn 2016.

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