Physical characteristics: This bird reaches about 6 inches (15.3 centimeters) and 0.5 ounces (15 grams). It has a dark, bluish gray back and head, white eye ring, and a gray-specked, yellow throat and belly. Males are slightly more vividly colored than females, and have a blackish stripe on the face.
Geographic range: This bird summers in Michigan, and winters in the Bahamas.
Habitat: Its summertime home is primarily forests of jack pine trees, usually preferring forests with many young trees whose branches dip
close to the ground and provide cover for their ground nests.
Diet: Kirtland's warblers eat insects, and occasionally berries, or pine needles.
Behavior and reproduction: Although the warbler is quite rare, a birder who knows where to look can readily see them flying between pine trees and nabbing insects in midair. In late spring to early summer, Kirtland's warblers build small cup-shaped nests on the ground under low-lying pine branches. Broods typically number four or five eggs. The eggs hatch in about two weeks, and the young birds leave the nest about a week and a half later. One of greatest dangers to the birds comes not from direct predation, but from the wily brown-headed cowbird, which lays its eggs in the warbler's nest. The warbler cares for the cowbird young, often neglecting its own chicks.
Kirtland's warblers and people: People from around the world come to Michigan in the spring and summer to spot this bi-colored bird. Kirtland Community College, located in the breeding area, holds an annual festival in the bird's honor.
Conservation status: The need for the Kirtland's warbler to breed in young jack pine stands in northern Michigan has contributed to its low numbers. In response, efforts to improve its habitat have occurred, and the number of breeding pairs is increasing. The U.S. Fish and Wildlife Service currently defines this species as endangered, but its ranking on the Red List has improved from Endangered in 1994 to Vulnerable in 2000. ■
FOR MORE INFORMATION
Bent, Arthur C. Life Histories of North American Wood Warblers. New York: Dover Publications, Inc., 1963.
Cassidy, James, ed. Book of North American Birds. New York: The Reader's Digest Association, Inc., 1990.
Dock Jr., George. "Yellow-Breasted Chat." In Audubon's Birds of America. New York: Harry N. Abrams, Inc., 1979.
Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye. The Birder's Handbook. New York: Simon and Schuster, Inc. (Fireside Books), 1988.
Garrett, Kimball L., and John B. Dunning Jr. "Wood-Warblers." In The Sibley Guide to Bird Life and Behavior, edited by Chris Elphick, John B. Dunning Jr., and David Allen Sibley. New York: Alfred A. Knopf, 2001.
Peterson, Roger Tory. A Field Guide to the Birds of Eastern and Central North America. Boston: Houghton Mifflin Co., 1980.
Berger, Cynthia. "Exposed: Secret Lives of Warblers." National Wildlife 23 (2000): 46-52.
Lichtenstein, G., and S. G. Sealy. "Nestling Competition, Rather than Supernormal Stimulus, Explains the Success of Parasitic Brown-headed Cowbird Chicks in Yellow Warbler Nests." Proceedings of the Royal Society of London 265, no. 1392 (2000): 249-254.
Price, T., H.L. Gibbs, L. de Sousa, and A. D. Richman. "Different Timing of the Adaptive Radiations of North American and Asian Warblers." Proceedings of the Royal Society of London 265 (1998): 1969-1975.
Weidensaul, Scott. "Jewels in the Treetops." Country Journal 23 (1996): 58-61.
Endangered Species Program, U.S. Fish & Wildlife Service. http:// endangered.fws.gov/ (accessed on May 5, 2004).
IUCN Red List of Threatened Species—Species information. http://www.redlist.org (accessed on May 29, 2004).
NEW WORLD BLACKBIRDS AND ORIOLES
Number of species: 103 species
phylum class subclass order monotypic order suborder family
New World blackbirds and orioles (called "icterids" as a group) are physically diverse in coloring, size, and shape. Common colorings are black, dark purple, yellow, brown, and orange. Bill size and shape is also variable—some species like the great-tailed grackle and the meadowlarks have long, curved beaks while others have shorter conical, or cone-shaped, ones. All blackbirds have a unique jaw structure that enables them to force their jaw and bill open, a practice known as gaping that lets them forage, or search for food, more effectively.
As their name implies, New World blackbirds are found throughout North and South America, as are orioles. Some species are also found in the Caribbean.
Grasslands and marshes are popular breeding grounds for icterids, but this diverse family of birds can be found in a number of different biomes.
Birds in the Icteridae family have a diverse diet, feeding on insects, seeds, fruits, and grains.
Blackbirds build their bowl-shaped nests in shrubs, trees, and reeds, with the exception of a few species that live in vegetation-free areas that build nests in rock crevices. Orioles build orb-shaped nests constructed of grasses that hang down from a tree branch. One species of Icteridae, the baybird, takes over abandoned nests of other birds. Others are parasitic, meaning that they lay their eggs in another bird's nests for the nest-owner to hatch and fledge, when the young bird is ready to fly on its own.
Depending on the species, male blackbirds have anywhere from one to up to fifteen female mates. Often those male birds that are polygynous (puh-LIJ-uh-nus; have more than one mate) live with a bird population that is mostly female.
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