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Wilsonia citrinahooded warbler

By Charles Vance

Geographic Range

Wilsonia citrina is generally found in the midwestern and eastern parts of the United States. The western boundary extends north from east Texas to central Wisconsin, and on the east can be found from western New York and Connecticut down to northern Florida. The hooded warbler generally migrates to Southern Mexico and Central America for the winters. (Johns, 2000)

Habitat

Wilsonia citrina generally nests in gaps in heavily forested areas, but stays away from the edge of the forest. Wilsonia citrina picks sites that have a well developed understory to build the nest in. The male and female prefer different habitats during the winter months. Males still prefer forested areas while females will take up in brushy fields and shrubby areas (Johns, 2000).

Physical Description

The upper tail and back are an olive-brown color, with the underside of the tail having white feathers. Both male and female birds have a black face with yellow around the eyes, but the coloring on the male is more drastic and distinctive compared to the shaded colors of the female. Wilsonia citrina also has yellow on the underside of the body and pink legs. (Robbins, et al., 1966)

  • Range mass
    10 to 11 g
    0.35 to 0.39 oz
  • Average length
    12.5 cm
    4.92 in
  • Average basal metabolic rate
    0.21538 W
    AnAge

Reproduction

Both male and female W. citrina sing during the process of attracting a mate. While birds will form pairs for mating purposes, it is frequently found that a mother's eggs have been fertilized by a neighboring male (Johns, 2000).

The female constructs a nest in the underbrush of a low lying area. The nest is constructed of bark and plant material, with an outer layer of dead leaves. Three to five eggs are laid, then normally incubated for about twelve days before hatching. After hatching, the chicks will fledge in about eight or nine days and continue their growth into adult birds. Juvenile birds will be capable of reproduction the next breeding season.

  • Breeding season
    April - June
  • Range eggs per season
    3 to 5
  • Average eggs per season
    3
    AnAge
  • Average time to hatching
    12 days
  • Average time to hatching
    12 days
    AnAge
  • Average fledging age
    9 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Males provide from 25% to 75% of feeding visits to young. Scientists had hypothesized that males that provide less parental care use their time and energy to seek matings with neighboring females instead. However, this turns out not to be the case. (Pitcher and Stutchbury, 2000)

Lifespan/Longevity

The lifespan of W. citrina is about 8-9 years.

Behavior

Wilsonia citrina is a migratory bird that summers in North America and migrates south nocturnally to Mexico and Cenral America for the winters. While wintering, the male and female birds often live in different habitats - the males in forests and the females in shrubbery. It is thought that this may have something to do with the sexual dominance of the male (Johns, 2000). While most males attract a single mate, some males will have two females on their territory. Hooded Warblers may avoid small areas of woods in order to increase the number of territories, and thus the chance of inter-pair fertilization.

Communication and Perception

The hooded warbler has two modes of singing. One involves repeatedly singing the same pattern, and the other is an irregular mix of 3 or 4 different patterns. Singing is used by both the males and females in attracting mates. The repeat mode may be used for attracting the mate, while the irregular mode is some sort of method of "negotiating" with nearby warblers (Wiley, et al., 1994).

Food Habits

Wilsonia citrina feeds primarily on small insects, spiders and other arthropods, either catching them while in flight or picking them off of forest vegetation (Johns, 2000).

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Predators of W. citrina include snakes, racoons and cats. The largest danger comes from the possibility of running into man-made structures during the nocturnal migrations (Whittam & McCracken, 1999).

Ecosystem Roles

While this species feeds on small insects and arthropods, it is not clear that it plays a unique role in the ecosystem, or that its function would have any impact on the ecosystem if it were removed. It has been reduced dramatically in number in various Canadian forests, but there is no apparent effect on those forests (Whittam & McCracken, 1999).

  • Ecosystem Impact
  • creates habitat

Economic Importance for Humans: Positive

It is not clear that this species has any positive impact on humans other than its aesthetic value and its contribution to animal diversity.

Economic Importance for Humans: Negative

This species has no negative effect on humans.

Conservation Status

Wilsonia citrina is generally abundant in the United States. In Canada, however, concern has been raised about the dwindling number of mating pairs and efforts are being made to study and prevent the loss of this species from the Canadian landscape. In some cases selective logging may actually help in that it provides a gap in the forest for W. citrina to live, yet doesn't create an edge to the forest. It is difficult for W. citrina to survive on the forest edge because of the increased presence of predators and the loss of desired habitat. (Whittam & McCracken, 1999). Hooded warblers are considered to be a species of special concern in Michigan.

Contributors

Charles Vance (author), University of Michigan-Ann Arbor, Kerry Yurewicz (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

June 1, 2000. "Georgia Wildlife Web Site; birds: Wilsonia citrina" (On-line). Accessed April 7, 2002 at http://museum.nhm.uga.edu/gawildlife/birds/passeriformes/wcitrina.html.

"Warbler Watch: Hooded Warbler" (On-line). Accessed March 22, 2002 at http://birdsource.cornell.edu/warblers/species/hoowar/.

Johns, M. 2000. "Hooded Warbler" (On-line). Accessed March 22, 2002 at http://faculty.ncwc.edu/MBrooks/pif/Bird%20Profiles/hooded_warbler.htm.

Patuxent Wildlife Research Center, "Hooded warbler identification tips" (On-line). Accessed April 7, 2002 at http://www.mbr-pwrc.usgs.gov/id/framlst/Idtips/h6840id.html.

Pitcher, T., B. Stutchbury. 2000. Extraterritorial forays and male parental care in hooded warblers. Animal Behaviour, 59: 1261-1269.

Robbins, C., B. Bruun, H. Zim. 1966. Birds of North America. New York, NY: Western Publishing Company, Inc..

Whittam, B., J. McCracken. 1999. "Bird Studies Canada report: Hooded warbler poductivity and habitat selection in southern Ontario" (On-line). Accessed 20 June 2003 at http://www.bsc-eoc.org/download/howareport.pdf.

Wiley, R., R. Goddard, A. Thompson. 1994. Use of two singing modes by hooded warblers as adaptations for signalling. Behaviour, 129: 57-75.

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