Green Frog — Part 3

Rana clamitans Latreille.

The Green Frogs come early from their hibernation in the mud and moss about the ponds. They appear early enough to feed upon the delicate fairy shrimps (Branchipus.) of icy March pools. The truth is, they are more or less active throughout the winter, if the temperature is not too low. It is interesting to keep American Toads and Green Frogs together under the same conditions, to compare their hibernating habits. Even with the temperature at 60 deg. F., the toads disappear early, and for weeks and months at a time will not so much as come to the surface. The frogs scarcely hibernate at all. They sit patiently in the water or on the moss, or possibly in shallow burrows in the moss. They take worms and small fish greedily all through the winter, whereas it is usually difficult to get toads to eat before the arrival of spring.

The eggs of the Green Frog are usually laid some time between the last of March and the last of April. The eggs are larger than those of the American Toad, and the jelly of the large mass (usually fastened to a twig or other support) is very firm, and remains so during the early development. The egg clusters are often laid during times of high water. Placed just below the surface of the pond and attached to the twigs of buttonbush, alder or other shrubs that are growing in the water, they are left some distance above the surface when the water recedes. If this receding comes before they are several days old and the jellymass considerably softened, here they continue to cling to their supports and soon dry under the influence of sun and wind.

The early development of the Green Frog eggs is rapid. The young embryos are light in colour and so may be distinguished from those of the Wood Frog and of the Leopard Frog, although easily confused with those of the Pickerel Frog. The tadpoles, like those of the Common Bullfrog, may live two years before the final metamorphosis. (The mouth structure of the Green Frog tadpole is similar to that of the Bullfrog tadpole.) It is not until the second summer, and possibly until the third, that the change to the frog form occurs.

During almost any of the warm months of the year we may find Green Frog tadpoles changing to the adults. The hind legs grow rapidly, and may be conspicuously barred with dark colour. The left arm appears first, thrusting itself out of the breathing-pore. (Fig. 237.) Then the right one breaks through the skin. The changes in mouth and eyes begin. The tail is slowly absorbed. (Fig. 239.) The ears are the last external sign to tell that the change is quite completed. The variation in the size, colour, and markings of the changing tadpoles is very great. Most curious is the fact that some tadpoles show the lateral folds and the colouring of the adult male or female long before the change is completed, while others take on the frog form entire before the lateral folds are well developed or before the sexual colouring is evident.

The activity and the spirit of adventure which characterize the Green Frog are evident very early, in fact before the tail is wholly absorbed. The young frog may sit contentedly in shallow water (Fig. 234) or float at the surface with only eyes and nose above (Fig. 233), but more likely he climbs out of the water on anything available. (Fig. 232.) Unlike the young. Bullfrog, which constantly hides under water or moss, the young Green Frog is curious and alert, and always in evidence.