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Northern Wood Frog — Part 3
This frog can be recognised at once because of the presence and distribution of red colour on the underparts. This colour is vividly displayed on the sides when the frog is in sitting position; considerable red is sometimes found on the upper surfaces of the body and legs, blending with the rich chocolate-brown of the upper parts. The dark brown or black patch of colour in the region of the ear will help to identify the frog sometimes, but very often this spot is no darker than the background of colour elsewhere. The iris is rich orange-bronze, instead of yellow, as in its near neighbour, Rana pretiosa. But from this species the smooth, firm texture of the skin on the soles of its feet will at once distinguish it. The tubercles under the joints of fingers and toes are unusual in size. There is great variety in the size and appearance of the spots on different individuals. Some are almost plain in colour and some are conspicuously spotted. The spots may be of large size or very small. They may be spots of solid colour or may have lighter centres. The spots may infringe on the lateral folds, in fact, sometimes small spots are aggregated along the lateral folds.
For the exact webbing of the toes. The web of the male is broader than that of the female. The first finger on the hand of the male is thickened and hardened at its base, and is dark-coloured and horny, especially on its upper surface. All of the fingers are unusually long.
Rana draytonii hibernates in the mud at the bottom of ponds and creeks in winter, when the air is colder than the mud and water. Here the frogs would be at the mercy of their enemies--the large water-beetles, water-snakes, and especially the leeches, except that the cold affects these enemies in the same fashion, and they are sleeping also.
In the region of middle California, this frog comes from its hibernation in late January or in February. The large egg-clusters are laid at once in the shallow water of ponds. It is said that the eggs hatch in about six weeks, and that the tadpoles become young frogs in four or five months. (Facts given by S. C. Coombs, Frog Ranch, South San Francisco, Cal.)
The young frog is very small in the first year and still during the second and third years,--in fact, it takes four or five years for it to attain a length of two and a half to three inches, and eight years or more to become full-grown. It is said by people of the Western Coast that RanaDraytonii is the best edible frog in North America, and that the flesh of the Eastern Bullfrog is tough and coarse compared with it.
Rana aurora is a delicately formed, smooth frog, less hardy than most frogs of North America. It is shy and wild, and difficult to keep in captivity, except in a perfect imitation of its environment. In such a place, it seems to enjoy equally sitting under the shade of ferns or in the water, and eats earth-worms greedily. Both male and female give high-pitched, jerky cries, expressing fright, when taken in the hand. One unusually large specimen opened his mouth wide and gave a prolonged high-pitched scream, reminding one of the similar sound produced by the Common Bullfrog.
Judging from the radical difference in the sizes of the frogs to be found in the spring, this frog requires four or five years to become full-grown. It changes colour rapidly, from dark rich browns to delicate shades of rosy tan. Rana aurora is a delicate, timid-looking frog, but, notwithstanding the promise of its name, it does not always compare in beauty with many of the other frogs of North America. It seldom has the richness of colouring that may be possessed by Rana draytonii, its neighbour on the Pacific Slope.
Rana aurora is easily confused with Rana draytonii because of the likeness, both in colouring and proportions. The former frog can be distinguished by the following characteristics: It has a longer leg, the greater length especially noticeable in the tibia. Its skin is very smooth, while that of Rana draytonii, especially in the full-grown frogs, is always tubercular, and may be extremely so (even on the ear). Rana aurora has a longer foot with a broader web, but with a much smaller inner sole tubercle.