USGS Bird Population - Essay Example

USGS Bird Population Generalist/opportunistic species have the survival ability to thrive in a wide variety of environments and habitats, and can live on a varied diet while specialist species survive only in a narrow range of environmental conditions and on a limited diet (Townsend, Begon, & Harper, 2008). Thus generalist/opportunistic species can easily adapt to changes in the environment whereas specialist species are prone to extinction.The Double Crested Cormorant is a generalist given that is common specie that thrives everywhere along the coast in North America (Wires & Cuthbert, 2006).

Indeed, it found as far north as Alaska on the west coast as well as New England on the east coast and as far south as Mexico and the Bahamas. It is also found in eastern Canada, in Great Britain, and Ireland. Its ability to survive on a variety of diets, which include fish, amphibians and crustaceans, also indicate that the Double Crested Cormorant is a generalist.The Great Blue Heron is also a generalist/opportunistic species. This species is found not only in freshwater and saltwater habitats but also in mangrove swamps, flooded meadows, lake edges as well as along the shoreline.

Indeed, it thrives in almost every part of North America, from Alaska and southern Canada in the North to Florida, Mexico and the Caribbean in the south. It is also found in South America, Greenland and England (Elliott, del Hoyo, Sargatal, & Imboden, 1992). Though the primary food of the Great Blue Heron is fish, it opportunistically feed on a variety of aquatic organisms such as shrimp, crabs, insects, rodents, amphibians, reptiles and other smaller birds.The Wood Stork is an example of a specialist given that it is found in limited habitat mainly tropical and subtropical climates of South America, Central America and the Caribbean.

It is also found in subtropical climates of the United States such as in the States of Florida, Georgia and South Carolina where they live on cypress trees in marshes and swamps (Ehrlich, Dobkin, & Wheye, 1992). The Wood Stork, which is an endangered species (Ehrlich, Dobkin, & Wheye, 1992), preys on a limited variety of aquatic organisms that include fish, frogs and large insects.The America Robin is indeed a generalist that is found in almost all parts of North America, from Alaska and Canada in the North to Florida and Mexico in the south (The Cornell Lab of Ornithology, 2011).

Thus is can survive in different types of environments though its habitat is mainly woodland. It is also found in the Caribbean, Greenland, and in Europe. The America Robin is an omnivorous bird that eats animals such as earthworms, insects, small snails, small snakes, and fruits, for example hawthorn, chokecherries dogwood, and sumac fruits, and juniper berries (The Cornell Lab of Ornithology, 2011).Works CitedEhrlich, P. R., Dobkin, D. S., & Wheye, D. (1992). Birds in Jeopardy. Stanford, CA: Stanford University Press.

Elliott, A., del Hoyo, J., Sargatal, J., & Imboden, C. (1992). Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Barcelona : Lynx Edicions.The Cornell Lab of Ornithology. (2011). American Robin. Retrieved June 6, 2011, from The Cornell Lab of Ornithology: http://www.allaboutbirds.org/guide/American_Robin/lifehistoryTownsend, C. R., Begon, M., & Harper, J. L. (2008). Essentials of Ecology. Malden, MA: Wiley-Blackwell.Wires, L. R., & Cuthbert, F. J. (2006). Historic Populations of the Double-crested Cormorant (Phalacrocorax auritus): Implications for Conservation and Management in the 21st Century.

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