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Dendroica magnoliamagnolia warbler

By Julie Neuser

Geographic Range

The Magnolia Warbler, during breeding season, is found in central and southern Canada, down into the northern United States, such as in Michigan, Wisconsin, and Minnesota. The warblers are commonly found in both the Appalachian Mountains as well as in the New England region, approximately as far south as North Carolina. In the winter however, the Magnolia Warbler migrates south, wintering from Mexico to Panama. It is occasionally found in the West Indies, the western and southern United States. (Cornell Laboratory of Ornithology, 2001; Curson, 1994; Griscom and Sprunt Jr., 1979)

Habitat

The name of the Magnolia Warbler is misleading because it is actually rarely found in Magnolia trees. It was named by Alexander Wilson who happened to see one of these birds in a magnolia tree in the South, on its annual migration. The Magnolia Warbler is instead found in damp coniferous forests, which include trees like pine, red maple, spruce, hemlocks, and balsam firs. It tends to dwell in the lower parts of the trees.

(Kaufman, 1996; Alsop, 2001; Harrison, 1984; Griscom & Sprunt, 1979)

Physical Description

The Magnolia Warbler is easily recognizable due to its distinctive yellow and black coloring. Its tail is black at the tip with large white spots which make up a band in the middle. The rump and most of its underparts of the Magnolia Warbler are yellow. It also has black streaks on its breast. Breeding males have a black face as well. Females are similar except that they also have more white on their wings as well as grey on their heads. Their colors tend to be a bit duller, and their patterns less distinct than those of the males. Juvenile Magnolia Warblers also tend to be duller in color, with more grey than black, as well as having some brown or olive coloring on the body. They also may have white bands around their eyes. The specific coloration patterns of the Magnolia Warbler varies greatly depending on the stage of life it is in (breeding or not-breeding, adult, juvenile, or first-year, male or female, etc.)

(Kulba & Reichwein, Date Unknown; Curson, 1994; Alsop, 2001)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    6.6 to 12.6 g
    0.23 to 0.44 oz
  • Average mass
    8 g
    0.28 oz
  • Range length
    12 to 13 cm
    4.72 to 5.12 in
  • Average wingspan
    19.68 cm
    7.75 in

Reproduction

The Magnolia Warbler is monogamous. During breeding season, the males grow very competitive and try to impress the females by showing off their distinctive coloring. The males also can get violent with each other at this time, fighting one another with their beaks and wings. Males also tend to sing cheerful tunes to the female they have chosen to mate with. (Alsop, 2001; Bent, 1953)

Magnolia Warblers create their nests in low tree branches or twigs, usually in the most dense areas of the forest. They seem to build rather messy nests, which are put together very carelessly, and are not very stable or secure. They are made up of twigs, weeds, hay, and grass.

The female Magnolia Warbler lays from 3-5 eggs at a time and they lay their eggs once a year. The eggs are white, creamy white, or sometimes greenish white. They are speckled with brown spots or splotches which can range from very dark to very light and very few to very many. The eggs are slightly glossy. They measure, on average, 16.3 by 12.3 millimeters. Incubation lasts 11 to 13 days.

After a chick hatches, its eyes open after about 3 or 4 days. The feathers become well developed after only about 8 or 9 days. This is also about the same time they first leave the nest and begin to find their own food. (Curson, 1994; Kaufman, 1996; Bent, 1953)

  • Breeding season
    May-June
  • Range eggs per season
    3 to 5
  • Average eggs per season
    4
    AnAge
  • Range time to hatching
    11 to 13 days
  • Range fledging age
    8 to 10 days

Females incubate the eggs and have a more active role in the raising of the young birds, but both the male and the female supply food to the young. Even after they fledge, baby birds remain close to one another and to their parents for about a month afterward. During this time, the parents continue to provide food for the young, however after this time they are on their own. (Bent, 1953; Alsop, 2001)

Lifespan/Longevity

The maximum lifespan of the Magnolia Warbler is recorded at 6 years and 11 months.

(Klimkiewicz, 2002)

Behavior

The Magnolia Warbler is usually found living by itself or in pairs. It is sometimes territorial in the winter months. It is usually rather easy to watch, because it lives so low in the forest, and also doesn't seem to be very shy, unless it is protectively guarding its young. It is quite active, and energetic, hopping and flying from branch to branch. It does not seem to mind attention as it sings almost constantly and often appears to be showing off its tail feathers, by spreading them or flicking them. Although they usually live alone, they don't seem to show any hostility toward other birds, of other species or their own.

(Alsop, 2001;Bent, 1953;Curson, 1994)

Communication and Perception

Food Habits

The Magnolia Warbler feeds almost exclusively on insects. It forages for its food in the lower or middle branches of the trees. It picks insects off of tree needles, leaves, and twigs, as well as sometimes from the undersides of plants and under the bark of trees. Sometimes it will also hover to search for food and fly short distances to catch its prey. During bad weather, when insects can be hard to find, the Magnolia Warbler will also feed on berries.

Foods eaten include: beetles, moth caterpillars, leafhoppers, aphids, spiders, worms, flies, plant lice and berries.

(Kaufman, 1996; Curson, 1994; Griscom & Sprunt, 1979)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • fruit

Predation

The Magnolia Warbler takes great care to hide its nest deep within the dense growth of the forest, in order to protect its eggs from predators. Cowbirds lay their eggs in Magnolia Warbler nests and the young cowbirds may eject eggs or young of their hosts. Hawks are known egg and young predators (Harrison, 1984; Bent, 1953)

Ecosystem Roles

The Magnolia Warbler eats insects which are harmful to woodland trees, such as plant lice, leaf hoppers, and beetles. The Magnolia Warbler also occasionally acts as a host species to the parasitic cowbird, which steals eggs and food from the warbler.

(Bent, 1953; Harrison, 1984)

Economic Importance for Humans: Positive

The Magnolia Warbler eats many insects such as moth caterpillars, aphids, and plant lice which can be problems for humans.

(Griscom & Sprunt, 1979; Kaufman, 1996)

  • Positive Impacts
  • controls pest population

Conservation Status

There have been accounts of both an increase and decline in the number of Magnolia Warblers. However it is important to note that the Magnolia Warbler is quite vulnerable to a loss of habitat. As many eastern spruce and fir forests are declining, due mostly to air pollution, the population of Magnolia Warblers is also likely to decline.

(Alsop, 2001)

Contributors

Julie Neuser (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, 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

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.

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

solitary

lives alone

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

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Alsop III, F. 2001. Birds of North America: Western Region. New York: DK Publishing.

Bent, A. 1953. Life Histories of North American Wood Warblers. Washington D.C.: Smithsonian Institution.

Cornell Laboratory of Ornithology, 2001. "Magnolia Warbler" (On-line). Accessed March 20, 2002 at http://birds.cornell.edu/BOW/magwar/.

Curson, J. 1994. New World Warblers. London: Christopher Helm Publishers.

Griscom, L., A. Sprunt Jr.. 1979. The Warblers of America. New York: Doubleday.

Harrison, H. 1984. Wood Warblers' World. New York: Simon and Schuster.

Kaufman, K. 1996. Lives of North American Birds. New York: Houghton Mifflin Co..

Klimkiewicz, M. 2002. "Longevity Records of North American Birds Version 2002.1. Pautuxent Wildlife Research Center. Bird Banding Laboratory. Laurel MD." (On-line). Accessed March 22, 2002. at http://www.pwrc.usgs.gov/bbl/homepage/longvrec.htm.

Kulba, B., P. Reichwein. "Warblers of Canada" (On-line). Accessed March 20, 2002 at http://collections.ic.gc.ca/warblers/species/mnwa.htm.

Tufts, R. 1986. "Birds of Nova Scotia" (On-line). Accessed March 20, 2002 at http://museum.gov.ns.ca/mnh/nature/nsbirds/bns0316.htm.

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