The island of Chicken Key, located approximately one mile offshore from the Main Estate in Biscayne Bay, was formed by the deposition of quartz and limestone sands by ocean currents. This habitat can be classified as beach dune, characterized a wind-deposited foredune and wave-deposited upper beach that is variably inhabited by pioneer species, especially sea oats. Historically, the island had a sand beach and low dune system on the east, but dumping of dredge debris in the 1940’s destroyed most of the dune. An 1899 survey by S. H. Richmond recorded a maximum elevation of three feet above sea level. Dredge spoil deposits increased elevations up to 10 feet on the northern two-thirds of the island. In August 1992, Hurricane Andrew swept across the island, significantly affecting mangrove populations and bird rookery. It did, however, have the beneficial side effect of removing decades of flotsam and litter dumped from passing boats. In 1996-1997, the County implemented the restoration of Chicken Key Bird Rookery, the goal of which was to restore a tidally connected mangrove forest and dune system, to remove dredged materials, and to re-create the island’s original topography. Mangroves on Chicken Key were an important roosting area and rookery for a variety of bird species. The mangroves on the southwest portion of Chicken Key were a major bird roosting area and rookery prior to Hurricane Andrew. Following the completion of restoration efforts in 1997, the mangrove canopy was re-established and water birds have begun to use the island once again.