Pickerel Frog — Part 2

Rana palustris Le Conte

The appearance of this frog will deceive us into believing that he is our familiar Leopard Frog, unless we are observing enough to see that the spots are square instead of round, and that as he makes one of his flying leaps there is a flash of orange under the back legs and posterior part of the body. These things mark him as a Pickerel Frog. He is in fact very closely related to the Leopard. However, he is always brown of some shade, instead of green. The head is usually less long and pointed than that of the Leopard. The spots do not have yellow rims. The Pickerel Frog has no large external vocal pouches, like those of the Leopard, but the throat, the region back of the eye and under the ear, as well as the sides, all expand considerably during the croaking. The male is much smaller than the female. It is he alone that does the croaking. This species has a distinctly unpleasant odour, due to the secretion of the skin. Because of this, it is not considered edible. The frog is used to a large extent as bait in pickerel-fishing, hence its name.

These frogs live out of the water (Fig. 221) more than in it, even at the breeding season. They go to the water to avoid their bird and snake enemies, to lay the eggs, to absorb the cool water through their shining coats. They spend the greater part of their time hunting, probably for caterpillars that feed on the violets and grasses, meadow caddis flies, butterflies and millers, flies, gnats, and beetles. It is likely that Pickerel Frogs find acceptable any insect that makes its home about the brook or that comes there to deposit its eggs in the water or to get honey from the flowers that grow there. They are known to feed on snails, small crayfishes, and aquatic amphipods and isopods. Pickerel Frogs are extremely common throughout the Eastern part of the United States. They are not to he found at all on the Great Plains of the West, where the Leopard holds supreme sway among frogs. They make their home not only in brooks and meadow marshes, but do good work in keeping pure the water of cold springs. We see their large eyes and palpitating white throats also in crannies at the mouths of surface drains.

The eggs of this species are laid in shallow water during the month of May. Frogs brought from the pond laid eggs on the nights of May 18, 23, and 26, 1902. The irregular egg masses are about two inches in diameter, and contain between two and three thousand eggs each. The upper half of the egg is rich brown in colour; the lower half cream-white. The eggs are small (1 1/4 mm.) and enveloped in triple spheres of transparent jelly. The earlier stages of the development take place very rapidly. The jelly holds its compact shape but a very short time; it softens, and the whole mass spreads and flattens. The tadpoles, which are light yellowish-brown in colour, leave the eggs very early. Eggs laid May 23rd were hatched May 27th. The tadpoles cling to the jelly side by side in rows and circles, with their heads up and their tails extending downward. The next day they are festooning the waterweeds as well as the jelly. Now they begin those circling tours, from which they settle to some new support, only to start off again in large circles, which give place to smaller ones until they find another support or drop lightly to the bottom. By the first week in June, the gills have become wholly covered, and the bits of life have grown to ordinary round-bodied "pollywogs," with the usual pollywog hunger. (1 The mouth structure of the pickerel frog tadpole is similar to that of the bullfrog tadpole.) From now on they vary greatly in size, some far outstripping the others, although all live under the same conditions. The larger ones change to the frog form in July and August; the smaller ones may be kept back in the process until September; and still others may delay the change until the following spring.