(Daudin, 1801) (American alligator)

Habitat: Aquatic; including many types of waterways, both natural and man-made.
Life History: Breeding begins in April; females lay over 50 eggs in a nest of leaves and vegetation up to 6 feet across. The eggs incubate for about 9 weeks; the female will defend the nest and hatchlings until they reach nine months of age.
Native Range: Coastal North Carolina south to southern Florida and the Keys, and westward through the deep south to central Texas and extreme southeastern Oklahoma.
Nonindigenous Range: Collected from Belleville and Westfield (New Jersey); North Yonkers, Pleasantville, Grassy Sprain Reservoir, New York City (sewer), Kenisco Reservoir, Middletown, East River, Brooklyn Museum Station (garbage can), and Westchester (New York); Virginia Beach, Hampton, Lucas Creek, Lake Anna, and Aquia Creek (Virginia); and unspecified localities in Lincoln and Wayne counties (West Virginia).
Impacts: Voracious predator feeding upon almost any fauna it can catch; despite many historic and recent introductions, harsh winters in the Mid-Atlantic region deter establishment.
Comments: The occurrence in a New York City sewer and related tall tales may have generated the urban myth of a population of alligators inhabiting the city’s sewage system.

  (Linnaeus, 1758) (common caiman)

Habitat: Almost any body of water, natural or man-made; with a diet that includes a variety of aquatic invertebrates and vertebrates, including terrestrial insects. 
Life History: An average of 22 eggs are laid in a mound nest during July and August.  The female guards her nest and continues maternal protection of the hatchlings.
Native Range: Southern Mexico to northern Argentina.
Nonindigenous Range: Collected from Windsor, East Hartford, and North Stonington (Connecticut); Taunton and Plainfield (Massachusetts); New York City (New York); south of Pittsburgh (Pennsylvania); and Arlington, Norfolk, Lake Fairfax Park, and eastern Henrico County (Virginia).
Impacts: Does not seem to tolerate temperatures below 1.7° C (35° F).  Not established in Mid-Atlanticstates, but established in Florida and Puerto Rico.  In Puerto Rico, nonindigenous Micropterus salmoides (largemouth bass) and Cichla ocellaris (peacock cichlid) that occur in waters with nonindigenous C. crocodilus are infested with larval caiman tongueworms (Pentastomida, Sebekidae). In Florida, caiman might transmit the same parasite to indigenous fish and crocodilians.
Comments: Trade in baby Alligator mississippiensis became illegal in the 1950s, and the pet industry imported thousands of young C. crocodilus into the U.S. as a substitute.  Numerous pet escapes and intentional releases were a consequence of that pet trade. The common caiman is subject to international and federal trade regulations, with additional restrictions in a variety of states.

  (Cuvier, 1807) (American crocodile)

Habitat: Brackish to saltwater habitats in tropical climates.
Life History: During the dry season, females lay an average of 38 eggs on a well-drained nest site.  After 90 days of incubation, hatchlings (25 cm in length) emerge. Females do not always guard the nest and hatchlings disperse from the nest site and the mother within a few days.
Native Range: Coasts of Mexico, Central America, northwestern South America, extreme southern Florida, and some islands in the West Indies.
Nonindigenous Range: A single 1 m long C. acutus was caught in the Great Dismal Swamp (Suffolk or Chesapeake counties), Virginia, in December 1976.
Impacts: It is unlikely that C. acutus could have survived a single winter in Virginia.
Comments: The American crocodile is a federally listed endangered species.