Green Frog

Rana clamitans Latreille.

Colour.—Extremely variable and changeable. Typically, the colouring is brilliant metallic green on head and shoulders and dusky olive (perhaps spotted) posteriorly. There may be a yellowish band (widening anteriorly) along the lines of the jaw from the shoulder forward. Throat of the male bright orange-yellow; that of the female, white, spotted with dark. Sides of the body often marked with large blotches of dark. (This is especially true of the female.) Legs spotted or barred with dark. (See Plate XIII for colouration of the Green Frog.)

Measurements.—Size somewhat above medium, i.e. male, 3 to 3 1/2 inches, female 3 to 5 inches. Legs relatively short; the length of the leg to the heel being much less than the combined lengths of head and body. Tibia and femur about equal in length.

Structure.—The skin may be rough. Head unusually thick through. Head somewhat pointed. Ear of male much larger than the eye; that of female no larger than eye, often smaller. (Figs. 229 and 230.) Body stout. Lateral folds conspicuous; a groove occupies the midline of the back. The web is broad; it leaves the last two joints of the fourth toe free.

Range.—Very common throughout eastern North America, including Canada and Florida.

As we walk along the path that skirts the meadow brook, we are surprised by a scream, followed by another and still another. Our curiosity demands that we investigate. The sound suggests a frightened bird, though there is almost no shrubbery for the concealment of a bird. We walk more slowly, and approach the brook. There is nothing to be heard now, except the occasional splashing of water as a startled tadpole rushes to safety from the shallow water; or the whirring of wings as a dragon-fly passes startlingly near to our faces. We walk on along the muddy bank of the little stream. Again we hear the sound ahead of us, and surely something is moving toward the water. Now we suspect that it may be a frog, and so we are on the lookout still more alertly as we proceed. This time we see the creature plainly--a small Green Frog. (Fig. 234.) It leaps high into the air and drops into the water, uttering the short, high-pitched cry. It is hard to believe that the sound which startled us was made by this small creature, but we remember that the "Screaming Frog" is one of the old names given to the Green Frog. Day after day confirms our experience. Year after year we become accustomed to the fact that young Green Frogs--especially in the spring months--give this short, frightened scream when they are alarmed.

The older frogs of this species make the same high jump, but they give a very different call when they take refuge in the water. (They may give the screaming call also, but I have not heard it.) This sound is very familiar indeed to every person who has been in the country. It is a nasal "chu-n-ng," or "k-tun-n-ng," so low-pitched that it may be almost or quite an octave below middle C. It is a cheerful, vigorous call, somewhat musical in quality. The croaking of the Green Frog is a sound still different, and is given from shallow water. It is explosive, prolonged, and low-pitched and is likely to be repeated five or six times in succession. When we hear it given with less than its usual force, we may be deceived into thinking that we hear the drumming of a woodpecker. It may be imitated very well by cutting on a table, with heavy shears, some kind of coarse resisting cloth. Or it may be imitated less well by tearing heavy cloth in a jerky fashion. It resembles the croaking of the Pickerel Frog, but has more strongly accentuated notes in it.

The explosive character of the sound will be better understood if we watch the frog when he is croaking. He works hard; there is no appearance of external vocal pouches (as in the Leopard Frog, Fig. 9), but the yellow throat and the sides expand with such force as to jerk the whole body forward. Slowly the distended parts sink in as the vigorous sounds proceed. Then the throat and sides swell out again, and there follows another explosion of sound. And so on over and over. One yellow-throated creature, hidden among the green slime and brown leaves of the pond margin, gulps out his ejaculatory remark; exclamatory responses come from other yellow throats hidden in other parts of the shallow water.

It is easy to confuse the Green Frog with the Bullfrog. This is not alone because the two look alike, but because both are more aquatic than most of the other frogs of eastern North America. From season to season they remain in the water or wander out on the bank only a few feet from the water. The Green Frog can always be identified by the conspicuous lateral folds of skin which extend from the eyes to the posterior part of the body. The Bullfrog has no such folds.