Distribution and Habitats

       Physiographic Regions and Centers of Speciation. - Amphibians are found in all physiographic regions of the southeastern United States. They are found from sea level to the tops of the highest Appalachian Mountains. Centers of species richness and endemism include the Appalachian Mountains, particularly at higher elevations (salamanders, especially the family Plethodontidae and the genus Plethodon), and the Atlantic and Gulf Coastal Plain (many salamanders and frogs, especially Amphiuma, Siren, Pseudobranchus, Necturus, and Haideotriton). Several of the frogs in Puerto Rico and the US Virgin Islands are endemic to the islands or have their primary centers of distribution within these islands.

       In the following section, the types of habitats inhabited by southeastern and Caribbean amphibians are briefly discussed. A more comprehensive discussion with references to the published scientific literature is in Dodd (1997). http://armi.usgs.gov/

       Aquatic Habitats. - Amphibians are found in all aquatic wetland types except those associated with the saline waters of the coast. Even there, however, some species occasionally are found in brackish habitats. Southeastern aquatic environments include temporary ponds, wetlands in pine flatwoods, saturated forested wetlands, cypress domes, bayheads, large swamps, wet prairies, lakes, streams, rivers, and man-made aquatic habitats including borrow pits and ponds at former mine sites. Much information on amphibian use of aquatic habitats is contained in state or regional books (e.g. Wright and Wright, 1932) and in numerous accounts of species in need of conservation.

       Large fully-aquatic salamanders (Cryptobranchus, Necturus) are typically found in larger rivers and streams, whereas small aquatic salamanders (Desmognathus, Eurycea) frequent small streams and seeps. In these latter genera, larval development occurs within the stream and, after metamorphosis, adults live along the wet stream sides or among the gravelly substrate. The salamanders Siren, Pseudobranchus, and Amphiuma inhabit various types of vegetated ponds and mucky swamps. Newts and most Ambystoma species require temporary ponds to complete metamorphosis, and premature pond drying is an ever present threat to their development. Of course, even salamanders that do not require water to breed need moist environments to prevent desiccation.

       As with salamanders, frogs use a variety of wetlands for reproduction. Most frog species have tadpoles which develop within ponds, lakes, wet prairies or other lentic waters. Fewer species use streams, rivers, or swift flowing waters (e.g., Rana heckscheri in rivers, streams, and oxbows in addition to lentic waters). Some frogs are very habitat specific, such as Rana capito and Hyla gratiosa, which require fishless temporary ponds for reproduction. Some species, such as Bufo terrestris, breed in a wide variety of wetland habitats.

       Terrestrial Habitats. - Although amphibians are usually associated with water, most species spend a substantial amount of time in terrestrial habitats. Individuals of some species often can be found at great distances from the nearest breeding ponds (Dodd, 1996). Franz et al. (1988) recorded a gopher frog (Rana capito) at a tortoise burrow 2 km from where the frog was marked. Such long distance movements probably are not unusual. Greenberg (1993) captured southern toads (Bufo terrestris), eastern narrow-mouthed toads (Gastrophryne carolinensis), and eastern spadefoot toads (Scaphiopus holbrooki) in Florida sand pine scrub between 5 and 6 km from the nearest known water source.

       Terrestrial refugia include caves, burrows of tortoises, pocket gophers, crayfish (especially by Rana capito) and other invertebrates, tree roots, rock crevices, surface debris, and probably many other subterranean habitats. Treefrogs often use arboreal retreats. Selected references on the use of terrestrial habitats by amphibians that require water to breed are found in Dodd (1997).

       Tropical Habitats. - In the Caribbean, much of the lowlands have been modified for agriculture and urbanization, although certain frogs have adapted well to human presence. Amphibian species richness is greatest in the high-elevation forests of the interior mountains of Puerto Rico, where frogs are found in habitats from the forest floor litter to the forest canopy. Certain species require bromeliads (e.g., the recently extinct E. jasperi), whereas others live in boulder caves (E. cooki) or in torrential streams (e.g., the recently extinct E. karlschmidti). All Eleutherodactylus require moist places to deposit their eggs.

back / next / home
table of contents