Mississippi is home to quite a few taxonomic families of frogs and toads, including Ranidae, or the true frogs (such as bullfrogs and leopard frogs), individuals of which are largely aquatic and can be found in ponds, lakes, and streams; Bufonidae, or the true toads; Microhylidae, or the narrow-mouthed toads; Pelobatidae, or the spadefoot toads; and Hylidae, or the treefrogs, a group that encompasses the chorus frogs (including the spring peeper and the upland and Cajun chorus frogs), as well as many other species that can be heard calling right now. Let’s take a look at some of these hylids.
Treefrogs are distinguished by the sticky pads at the ends of their toes, which enable them to climb. They are typically found in trees and shrubs near sources of water. In the southeastern U.S., one of the most common species is the American green treefrog (Hyla cinerea). As its name suggests, this frog is typically bright green. However, like other treefrogs, it is capable of changing color to adapt to changes in temperature and environmental surroundings. It usually, but not always, has pale stripes running along its sides, and its skin is very smooth. The call is a nasally quank that carries for a good distance. Large choruses of this frog can be heard in almost any wet, wooded area.
Another common species is the squirrel treefrog (Hyla squirella), a small frog with a raspy call that is reminiscent of a squirrel’s barking sound. This extremely variable species may appear almost any color from bright green to dusky brown, depending on environmental conditions. At first glance, a bright green specimen of the squirrel treefrog might be mistaken for a green treefrog. However, the squirrel treefrog is smaller and always lacks the pale lateral stripes of the green treefrog. Squirrel treefrogs were formerly restricted to the southern half of Mississippi, but have recently expanded their range northward.
The next three species to be discussed, the common gray, Cope’s gray, and bird-voiced treefrogs, can be visually separated from the green and squirrel treefrogs by virtue of their bumpy skin. Like all treefrogs, they are more likely to be heard than seen, so it is still a good idea to learn to recognize them by their calls.
As their name suggests, gray treefrogs are frequently mottled gray in color, although they may also be various shades of green or brown—again, depending on temperature and habitat. The two species of gray treefrogs, common gray (Hyla versicolor) and Cope’s gray (Hyla chrysoscelis), look identical and are impossible to distinguish from each other in the hand. This is due to the fact that one species, the common gray treefrog, is thought to have diverged from the other, the Cope’s gray treefrog. Interestingly, common gray treefrogs are tetraploid, meaning that they have four pairs of chromosomes (i.e., genetic material)—twice the usual number. Tetraploidy is fairly common in plants and invertebrate animals, but it is not as frequently observed in vertebrates. While common gray and Cope’s gray treefrogs cannot be reliably distinguished from each other by sight, they can be easily identified by sound. Both species have low-pitched trills, but the Cope’s gray treefrog’s call is faster and more snore-like than the drawn-out trilling of the common gray treefrog. If you are a Mississippian, though, it's possible that you will not need to distinguish between the two, since the common gray treefrog may occur in only the northernmost sliver of the state: http://maps.iucnredlist.org/map.html?id=55687. The Cope's gray occurs statewide: http://maps.iucnredlist.org/map.html?id=55448.
Bird-voiced treefrogs (Hyla avivoca) look like smaller versions of gray treefrogs. One quick way to identify them in the field is to look at the ventral portions of their legs; unlike gray treefrogs, which have bright orange skin in this area, bird-voiced treefrogs have greenish-yellow. You should have no trouble with identification if you hear the frogs, though; the whistling, bird-like call of the bird-voiced treefrog is drastically different from the sounds of gray treefrogs. Also, while you could find gray treefrogs in almost any type of forest, bird-voiced treefrogs tend to be most common in swampy woods, especially those containing cypress and tupelo trees. This is one of my favorite frog species in the state.
The pine woods treefrog (Hyla femoralis) and the barking treefrog (Hyla gratiosa) are two species found in the deep southeastern portions of the U.S. Unfortunately, I have had few encounters with either, and have heard pine woods treefrogs only in forests on the coast. However, a friend and mentor of mine has heard that species as far north as Newton County, Mississippi, so it is certainly possible to find them fairly far inland. They have strange calls—perhaps best described as sounding like hyperactive Morse code messaging. The call of the barking treefrog, on the other hand, is throatier in sound than the green treefrog’s call. Choruses of this species bring to mind—well, for me, anyway—hundreds of bouncing rubber balls. The barking treefrog frequently has dark spots and is also noticeably bumpy-skinned, making it easy to distinguish from green treefrogs. In the hand, pine woods treefrogs could be mistaken for squirrel treefrogs, but their inner thighs have rows of pale spots, unlike those of squirrel treefrogs.
The tiny, aptly-named cricket frogs are not technically treefrogs, as they belong to the genus Acris. Nevertheless, they are hylids, and, like their relatives, they can commonly be found in vegetation near water. Unlike treefrogs, cricket frogs tend to stay very low to the ground. The southern cricket frog (Acris gryllus) and the northern cricket frog (Acris crepitans) are the two most common species in the state. They are similar in appearance, and their insect-like calls are also a bit difficult to distinguish from each other. However, the southern cricket frog has a raspier sound than the northern. Both of these tiny frogs can be found in grasses and herbaceous vegetation near water.
So much for the adult hylids—but what about the earlier life stages: eggs and larvae? Well, if you peer into small ponds, woodland pools, roadside ditches, or potholes on old dirt roads, you might be lucky enough to see these. Frog eggs are in clusters, while toad eggs are in strings. Tadpoles may take a month or more to fully metamorphose. May the summer months be hopping!
Sources
The IUCN Red List of Threatened Species, http://www.iucnredlist.org/
Species Profile: Cope’s Gray Treefrog (Hyla chrysoscelis), Savannah River Ecology Laboratory, http://srelherp.uga.edu/anurans/hylchr.htm
Species Profile: Pine Woods Treefrog (Hyla femoralis), Savannah River Ecology Laboratory, http://srelherp.uga.edu/anurans/hylfem.htm
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