First a note: To put geologic time into perspective, Don Eicher, in "Geologic Time" suggests compressing all of the 4.6 billion years of earth history into a single year. On that basis, the oldest rocks date from mid-March, life in the seas appeared in mid-May, but land plants and animals did not emerge until late November. Dinosaurs became dominant in mid-December, but disappeared on the twenty-sixth, concurrant with the uplifting of the Rocky Mountains. Manlike creatures first appeared sometime during the evening of December 31, and Columbus "discovered" America about three seconds before midnight. And, as a side note, San Salvador Island was the site of first landfall for Columbus in 1492.
On to birds....There are 5 billion birds in North America alone that move out of the tropics to the north every spring heading for the northern summers, food and breeding resources. These are neotropical birds. The neotropical region is between the Tropic of Cancer and Tropic of Capricorn. The description of Neotropical birds, which includes 361 species, from the book, "Neotropical Migratory Birds" is: Western Hemisphere species, all or part of whose populations breed north of the Tropic of Cancer and winter south of that line."
One of the major routes of migration is along the Atlantic coastline southward to Florida called the Atlantic Flyway. In the fall, some species travel down the Florida peninsula, along the island chains of the Bahamas, Cuba, and the West Indies, enroute to South America.
In a study done between 1978 and 1987 by wildlife biologists and scientists, 20 species of neotropical songbirds showed a decline in numbers--some as high as 90%. The number one reason is loss of habitat. Other contributors to the songbird's deline are:
-air polution and pesticides--although DDT is banned in the U.S., it
is not banned in Latin American countries.
-a change in farming patterns, from small "family" farms to corporate farms which take up more land.
-tall buildings and windowpanes. Estimates run between 100 and 976
million bird deaths per year.
-cowbirds are another reason. Instead of building their own nests,
they lay their eggs in other nests, particularly the easy access
nests of neotropical birds--cup-like nests often close to the
ground which also gives easier access to predators. The cowbird
eggs usually hatch first and the neotropicals cannot compete for
food. Scientists particularly fear this fate for Florida's
Prairie Warblers and Black-whiskered Vireos.
It is estimated that 179 bird species breed in Florida, and approximately 300 species are Spring and Fall migrants and winter residents.
Everglades National Park was established in 1947 to protect South Florida's rich resources. One of the park's principal activities for tourists has been the birdlife. As of 1984, there were 347 known species. At least 4 species are now extirpated. Many others are now rare, endangered, or of management concern.
For almost a century engineers reconfigured the rivers and wetlands of the Florida Everglades to benefit agriculture, condos and beach resorts. The water dried up and many species thinned out, some to the point of disappearance. Today, activists and politicians have just begun to correct the damage. For the first time, starting in 1993, a public projects work is being reversed--to right an environmental wrong.
The Everglades is one of the most imperiled regions in the United States. Historically it was a mosaic of plants and animals that covered 13,000 square miles. Today it is a fragile ecosystem defined by extensive plumbing works--a network of canals and pumping stations that control the movement of water. Even the futuristic view of saving the Everglades is on a very reduced scale.
Today the Everglades are crisscrossed with 1400 miles of canals, levees, spillways and pumping stations. Little more than half of the original 4 million acres, south of Lake Okeechobee, come anywhere near its original state. And, half of that is locked into water conservation areas which deprive it of sheet flows. It is now more like a resevoir than marshes--thus depriving many birds and animals of habitat and food resources.
It was between 1948 and 1971 that the Army Corps of Engineers created this "marvel" which is an ecological disaster. By the time this disaster was clear to nearly everyone, some put the estimates of wading bird populations at less than 10% of their total before the mass drainage.
The Everglades lies at the intersection of tropical and temperate, making it the only true subtropical wilderness in the U.S. It is refuge to 56 declared endangered or threatened plant and animal species. The Everglades is one of only three sites in the world declared an International Biosphere Reserve, a World Heritage site, and a wetland of international importance.
Colonies of egrets, herons, and storks that once contained tens of thousands of birds have shrunk by 95% since the 1930's. Once abundant species like the Wood Stork are now near extinction. Two others that are endangered are the Snail Kite and the Cape Sable Sparrow.
Life for the Everglades is now out of balance. By altering the hydrology we have forced entire colonies of birds to abandon their traditional nesting sites. Scientists are now beginning to understand the importance of today's Everglades. For example, the wetlands east of today's Everglades were the perfect depth to serve as the main feeding area for hundreds of thousands of birds fattening up for breeding.
Birds of the Bahamas, like all island birds, are strikingly different than any others in the world. Island birds often become flightless and even tame. Many are found only on one or two islands. The West Indian Flamingo is the national bird of the bahamas, now highly endangered. Other species can be found in the "Field Guide" which I have compiled of birds of both South Florida and the Bahamas (particularly San Salvador Island).
Useful tips for Identifying Birds:
-consider the size
-consider field marks (color, shape, bill size & shape, tail
size and shape and stripes).
-look at the behavior, i.e., clinging to tree trunks, ground
-the sound of their songs
Also included in the field guide, in addition to hundreds of colored pictures of the birds, is an explanation and description of the many habitats we will encounter in both South Florida and San Salvador, Bahamas. These will further help to identify species of birds.
"A Field Guide to Birds of the West Indies," James Bond, 1993
"The Ecology of Migrant Birds: A Neotropical Perspective," John H.
"Checklist of Birds of the West Indies," James Bond, 1950
"Birds of the Bahamas," Andrew Patterson, 1972
"Where Have All the Birds Gone?", John Terborgh, 1989
"The Collins Guide to the Birds of New Providence and the Bahama
Islands," P.G.C. Brudenell-Bruce, 1975
"Neotropical Migratory Birds," Richard M. DeGraff & John H. Rappole,
"Florida's Birds," Herbert W. Kale II & David S. Maehr, 1990
"Birds of the Tropics," John A. Burton, 1973
"Birds of the Carribean," Robert Porter Allen, 1961
"Redeeming the Everglades," Mark Derr, AUDUBON MAGAZINE, 1993
"Back to the Everglades," Norman Boucher, TECHNOLOGY REVIEW, 1995
"America's Endangered Ecosystems," Robert L. Peters & Reed F. Nogs,
"The Significance of Marine Biodiversity," Sylvia A. Earle, OCEAN
"Avian Nations," David Rains Wallace, WILDERNESS, 1990
"The Mysteries of Bird Migration," Wendy Hale, Peggy Lantz, Neta
Villalobos-Bell, FLORIDA NATURALIST, 1989
Numerous Web Sites
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