In the remnant Everglades, however, the slow, dry-season recession of a much larger quantity of flowing water no longer takes place. Instead, impounded pools that accumulated during the wet season are rapidly drawn down. Not only has most habitat vanished as a result of these massive changes, but less water is available for the remaining wildlife. Fourteen animal species in the Everglades are now endangered. Many others are threatened or, while not formally listed, are declining.
Scientists use wading birds as a measure of a wetland ecosystem's environmental health.
For every bird you now see in the Everglades, in the early 1900s you would have seen at least ten. In other words, at least 90 percent have vanished. A drought between 1988 and 1991 exacerbated the damage to wading birds and water animals by destroying their food base and also increased the competition among human and wildlife needs. By 1989 only 5,000 wading-bird nests and 15 major colonies were counted, a very low number. In 1990, the number of nests dropped to about 1,000.