Gopher Frog — Part 2

Rana aesopus Cope

This frog is so wary and has such strong habits of hiding, that but few specimens have come to light. The wariness of this species has resulted in a habit of spasmodic instead of continuous activity. Its method, like that of the cricket grasshopper, is ludicrous to observe. It remains absolutely quiet for minutes at a time, relying on its protective colouration until the danger is well-nigh upon it. When the movement comes, it is with startling suddenness and despatch, leaving the frog statuesque again and observant, but in a new place.

Rana aesopus is comfortable in water, though not conspicuously a water-frog. It sits with head and shoulders protruding from water-weeds, invisible because of the colour and spotting of its dress. When the air becomes cooler than the water, it withdraws under the surface, and rests for hours, even days, at a time, with motionless flattened body, closed eyes, and arms and legs in hibernating position.

Outside of the breeding season, it lives solitary in gopherholes, hence its name. These so-called gopher-holes are the burrows of a Florida highland turtle. The burrow--about eight inches high, and fourteen wide, and sometimes as long as thirty feet--extends obliquely and irregularly through the sandy soil, starting under a clump of palmetto, or under a log, stump, or fence. The frog sits at the mouth of the burrow, watching for an unsuspecting insect, bird, or batrachian. It disappears so quickly at the approach of danger, that not only is it seldom seen, but, to be captured, must in all cases be dug out of the burrow.

This frog seems especially fond of toads as an article of diet. It ejects the poison from the mouth as soon as it has swallowed the toad. A toad of surprisingly large size can be managed, owing to the unusual development of the jaws and throat of this species. If the toad is too large to be all swallowed at once, so that the poison can be sent out through the mouth almost immediately, the frog gives up the attempt and disgorges the toad after about fifteen minutes. This time, however, is sufficient to allow some action of the poison to take place, and the frog shows many signs of discomfort. It has convulsive movements of the muscles, it leaps blindly upward, and finally, lowering the head and opening the cavernous mouth, uses the hands in frantic efforts to remove the irritation from there. During several weeks of captivity, Rana aesopus fed almost wholly upon toads, of species lentiginosus, woodhousei, and fowleri. This habit of eating toads may be duplicated in the case of Rana catesbiana. At least this frog has been found dead with full-grown specimens of Bufo fowleri partially swallowed.

RANA ONCA, COPE (1 Rana fisheri Stejneger. Annotated List of Reptiles and Batrachians Collected by the Desert Valley Expedition in 1891. Leonhard Stejneger. North Amer. Fauna, No.7. 1893.

Also Rana draytoni onca Cope. Cope's Batrachia of North America.)

This species of frog (Fig. 257 and Colour Plate II) is not nearly related to the black-cheeked frogs of the Pacific Slope. It is apparently much nearer the eastern Rana clamitans, and the spotted frogs Rana pipiens. The general colouring, also the shape and proportions of head, body, and legs are remarkably like those of Rana clamitans (Fig. 230); the spotting reminds one of Rana pipiens (Fig. 197), but differs in that it represents a temporary colour pattern instead of a permanent one. Rana onca never attains the size of either of these other frogs.

Rana onca is a very bright, active little frog. It eats worms and insects greedily. It will try to take a worm away from a companion frog, biting at the frog's head again and again. In locomotion it proceeds by short hops, given in quick succession with short toad-like legs.

The power for rapid change of colour is considerable. The frog may be brown or green, of light or dark shade. The spots may or may not be rimmed with light colour. They may be darker or lighter than the background of colour. When lighter, they are shining gold or bronze. There is much iridescence in the colouration. In fact, the young frogs may wear a coat everywhere rich in metallic lustre.

The frogs examined have shown no external vocal pouches. The large webs and the unusually large tympanum make this frog easy of indentification within its western range.