a b c d Figure 6.10. Reptiles are not well represented in tidal marshes: (a) American alligator (Alligator missis- sippensis) frequents tidal fresh marshes and coastal impoundment; ( b) American crocodile (Crocodylus acutus) occurs in saltwater and mangrove swamps from the tip of Florida into Colombia and Ecuador; (c) diamond-backed terrapin (Malaclemys terrapin) is the most common turtle found in estuaries; and (d ) Gulf salt marsh snake (Nerodia clarkii clarkii). (a: Adam Mackinnon; b: Tomás Castelazo; c: Ryan Hagerty, U.S. Fish and Wildlife Service; d: Kelly Jones) (Pseudemys floridana) frequent Gulf Coast environments. One exception is the southern black needlerush marshes and fresh tidal leopard frog (Rana utricularia), which has marshes. Sea turtles nest on ocean beaches been reported in brackish marshes with from Virginia south, with the loggerhead salinities as high as 21 ppt but more typi- turtle (Caretta caretta), a federally threat- cally less than 1 ppt ( Pearse 1936 ). On occa- ened species, being the most abundant of sion, one might expect to find a transient those nesting in the United States. Archie frog or toad from the adjacent upland or Carr National Wildlife Refuge (Atlantic freshwater wetland along the upper edges of Coast of Florida) contains the most impor- a salt or brackish marsh. Frogs and amphib- tant nesting area in the western hemisphere ians characteristic of a region are likely with as many as 1,000 nests per mile inhabitants of tidal freshwater wetlands. reported (www.nmfs.noaa.gov/pr/species / turtles/ loggerhead.htm). Mammal Habitat Amphibians are virtually absent from salt and brackish marshes as salamanders A variety of mammals have been observed and frogs tend to be restricted to freshwater in North American tidal marshes (Table 6.8). 202 Chapter 6.