The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
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The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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The term bellwether came from the practice of putting a bell on the leader of a flock of sheep. The term is now used to describe an indicator of a complex of ecological changes. Bellwether species are also called indicator species and are seen as early warning signs of environmental damage and ecosystem change.
Ecologists have identified many bellwether species in various ecosystems, including the Attwater prairie chicken(-Tympanuchus cupido attwateri), the Northern diamondback terrapin(Malaclemys terrapin terrapin), the Northern and Southern giant petrels (Macronectes giganteus and M. halli), and the polar bear(Ursus maritimus). There are many more. Problems with these species are extreme indicators of troubles within their ecosystems.
The Attwater prairie chicken is almost extinct. It once numbered in the millions in Louisiana and along the Texas coast. The Northern and Southern giant petrels, large scavenger birds of the Antarctic Peninsula, are also heading towards extinction as commercial fishing fleets head further and further south. In Massachusetts' Outer Cape, conservationists are trying to save the Northern diamondback terrapin. Troubles for the Arctic polar bear are indicating ecosystem change in the Arctic, as humans interact more and more with that ecosystem.
Helvarg, David. "Elegant Scavengers: Giant Petrels are a Bellwether Species for the Threatened Antarctic Peninsula." E Magazine, November/December, 1999.
Walsh, J. E. "The Arctic as a Bellwether." Nature, no. 352 (1999): 19–20.