BIODIVERSITY IN PERIL:
THREATENED AND ENDANGERED SPECIES
According to The National Research Council (NRC) of the National Academy of Sciences biennial review, “Toward Restoring The Everglades”, a number of species are in decline. Much of this decline is due to loss or degradation of habitat. Some distinctive Everglades habitats, such as custard-apple forests and peripheral wet prairie, have disappeared altogether, while other habitats are severely reduced in area . According to the NRC, tree islands cover less than 5 percent of the Everglades, but they number in the thousands, ranging in area from less than 10 square meters to more than 173 acres . The systematic loss of tree islands from the central Everglades is of special concern because of the long time to establish, their high species diversity, and the disproportionate role they play in nutrient cycling and in supporting wildlife populations.  Between 1950 and 2000 the Everglades Protection Area lost roughly 28 percent of its peat soils by volume due to drying, oxidation, and burning. That loss has been especially pronounced in northern WCA-3A, WCA-3B, and northeast Shark River Slough.
According to The National Park Service there are 23 Federally listed threatened or endangered animal species in the federally protected areas of the Greater Everglades Ecosystem, with many more included on state lists. Species on the Federal endangered list include the Florida panther, the American crocodile and the alligator, the West Indian manatee, the wood stork, the Cape Sable seaside sparrow, the red-cockaded woodpecker and the snail kite. The snail kite is the most endangered vertebrate in Florida after the Florida panther. The population of snail kites has dropped from more than 3,500 birds to fewer than 650 over the past ten years. The main reasons have been the raising and lowering of water levels in Water Conservation areas where most had nested since the 1970s, exacerbated by regional drought. In recent years, conditions in Water Conservation Area 3A (their main area of concentration) have resulted in poor reproduction, reduced juvenile survival, and reduced numbers of kites nesting there. 
In the Florida Fish and Wildlife Service (FFWS) five-year reviews published between 2007 and 2009, aside from the list of over 60 threatened species, five animal species were assessed as actually declining, including three species that primarily inhabit upland areas—the eastern indigo snake, the Florida grasshopper sparrow, and the Florida scrub jay—and two wetland species—once again the Everglades snail kite and the wood stork, although the wood stork population increased in South Florida during the 2008-2009 breeding season. Audubon’s crested caracara an upland hawk, was considered too poorly surveyed to assess trends. In 2003 the smalltooth sawfish, which occurs in tropical marine and estuarine areas in Florida from Charlotte Harbor to Florida Bay, was added to the Endangered Species list. The FFWS list of currently threatened species can be found here.
Other useful websites on challenges to endangered species: