True Frogs, True Toads, and More

American toad (photo taken in Arkansas)

Summer may be waning, but there is still plenty of time to look and listen for frogs and toads in woodlands and wetlands throughout southeastern North America.  I’ve discussed the taxonomic family Hylidae—the treefrog group—in previous posts, so now I will examine species in the families Ranidae (or the true frogs), Bufonidae (the true toads), Microhylidae (the narrow-mouthed toads), and Scaphiopodidae (the spadefoot toads).

Of course, habitat determines which families of frogs that you are likely to encounter in a given area.  Moist wooded areas and gardens are good places to find members of Bufonidae, the true toads.  These mostly terrestrial amphibians possess neurotoxin-producing parotoid glands, so if you ever touch a toad, just be sure to keep your hands away from your eyes and mouth!  Toads are otherwise harmless.  (Well, unless you're a bug.)

One of the most abundant toad species in Mississippi is the Fowler’s toad (Anaxyrus fowleri).  Its distinctive call is a somewhat raspy, unmusical bleat (which is similar to that of the Woodhouse's Toad, the species in the linked audio file).  The American (Anaxyrus americanus) and southern toads (Anaxyrus terrestris) are two of the other common species in the state, and both have slow, drawn-out trills that you may hear in the evening.  The oak toad (Anaxyrus quercicus) is a fairly common but hard-to-find amphibian in the southernmost third of the state.  It produces a mellow peeping sound.  Yet another possible find in southern Mississippi is the Gulf Coast toad (Incilius valliceps).  Its call is lower in pitch than that of the southern toad.

Spadefoot toads are a separate family that have a hard, sickle-shaped spade on each rear foot that they use to burrow into sandy soil.  The eastern spadefoot (Scaphiopus holbrookii) is the only species that occurs in the southeastern United States.  It is widely distributed but local in Mississippi, and the call is a very loud, throaty sound. 

If you hear a whiny, high-pitched nasal bleat while walking around a pond or weedy ditch, try not to be too alarmed.  It’s not a half-submerged goat, but an eastern narrow-mouthed toad (Gastrophryne carolinensis), the plump, small-headed Microhylid that is also sometimes called the eastern narrow-mouthed frog. 

When you think of frogs, you probably also think of water, and there are several frog species that spend their lives around lakes, ponds, streams and marshes.  These are the true frogs, or the family Ranidae.  One of the most abundant and attractive Ranids is the southern leopard frog (Lithobates sphenocephalus).  The leopard frog, which can be green or brown, is named for the many dark spots that cover its back and legs.  The call of this species is a rolling series of clucks and croaks.  A frog that appears fairly similar to this one is the pickerel frog (Lithobates palustris).  The spots on this brownish frog are square, and its call is a low-pitched snore. 

If you're near a pond and hear a sound similar to the thump of a rubber-band, you’ve probably heard the bronze frog (Lithobates clamitans clamitans), a medium-sized brownish subspecies of the green frog.  In the northeastern corner of Mississippi, the greenish version is present instead of the bronze frog.

The largest Mississippi frog is the American bullfrog (Lithobates catesbeiana).  Nearly everyone is familiar with this huge frog that produces a deep sonorous rooum-rooum similar to that of a bull.  And if there’s a frog that sounds like a bull, then it shouldn’t be terribly surprising for there to also be one that sounds like a pig!  The pig frog (Lithobates grylio) occurs in the southern portion of the state and closely resembles the bullfrog.  Its snout is more pointed, however, and the fourth toe doesn’t extend past the webbing as it does on the bullfrog.  Its call is a series of deep hoglike grunts. 

There are a few other Mississippi frogs that are very local or rare, including the gopher frog (Lithobates capito), the Mississippi gopher frog (Lithobates sevosus), and the river frog (Lithobates heckscheri).  Notably, the Mississippi gopher frog is a federally endangered species found in only a few locations on the coast.  Its rarity is a reminder of how fragile ALL amphibians and their habitats can be, so be sure to tread carefully in the frog environs that you may visit.


Sources:

The IUCN Red List of Threatened Species, http://www.iucnredlist.org/

USGS Frog Quiz, https://www.pwrc.usgs.gov/frogquiz/index.cfm?fuseaction=main.lookup