Hyla of the Pine Woods — Part 6

Hyla femoralis Latreille

Chorophilus nigritus Le Conte.

Colour; Changeable from a colour so dark that it is nearly balck, to flesh colour. When light, the colouration may be bluish or ash grey, fawn colour, or even salmon or red in tone. Iris golden or copper-coloured. There is a dark stripe, which begins at the muzzle and extends through the eye and ear, and less conspicuously to the middle of the side of the body or beyond. This dark colour is bordered below by a light band which extends to a point back of the arm. The immediate edge of the jaw is dark. There may be a pattern of dark lines or spots on the back, head, and legs. This pattern consists typically of the following: 1. Three longitudinal stripes (or series of spots). The middle one of the three occupies the midline of the back and may fork posteriorly. The two others extend backward parallel to this, from the posterior angles of the eyes. 2. A transverse band between the eyes connected with the median stripe. 3. Crossbands, or more or less irregular lines of spots, on the hind legs. The underparts are yellowish white. The throat of the male is greenish yellow. (See Studies of Chorophilus)

Pickering's Hyla is not the only tree frog that sings in ringing choruses in early spring. In the Southern States the Swamp Tree Frog is heard singing in late January and early February, usually before Pickering's Hyla has begun peeping. The chorus of the Swamp Tree Frog proceeds from ditches, marshes, and pools, especially in low lands. These tree frogs are partial to temporary pools which are wholly shut in from approach by tangled growths of shrubs and woody vines. From such sheltered, sunny places they sing throughout many of the days, and of course during the night, until late April, when the breeding season is over.

The chorus is not so penetrating as that of the Pickering's Hyla, nor has it the ringing sleigh-bell character of the latter. It is soft, relatively low-pitched, and is said to have a soothing sound that swells and recedes "like the waves of the seashore."

However, the chorus is loud enough, so that it is usually attributed to some large frog (Rana.) The single call is a somewhat musical rattle that lacks great carrying power. It is not shrill. (The pitch varies with the individual between E above middle C and C above.) There is a slight rise in pitch, an increase in emphasis, and the crepitations are not especially rapid (The call is not so loud nor so sharp in quality as that of the Cricket Frog (Acris); the crepitations are not so rapid.). The call conveys to the mind something of the idea of gentleness and comfort so distinctly given by the trill of the Common Tree Frog. The call is given by the male only; the inflated throat-pouch is large.

The Swamp Tree Frog stays about the marshes throughout the summer and fall. We may sometimes hear the isolated call from marshy land during the hottest part of the summer, but on the whole, the species is rather silent except during the breeding season. These frogs seek refuge in the water when they are disturbed, but are very poor swimmers, and soon come back to the shore or crawl out on some miniature log. They are seldom seen after the spring months, owing to their minute size, their protective colouration, and their silence. They feed upon flies, beetles, and various insects that frequent marshy places.

The Swamp Tree Frog is slender and delicate in appearance. It has great power to change its colour between light and dark shades. It has a colour pattern that not only is variable but has the evanescent character common among the Hylidae. That is, each tree frog has its own distinctive pattern of dress-we can scarcely find two alike among several dozens caught in the same locality-and in addition to this great variation, the given patterns may be wholly absent at one time, faintly outlined at another and prominently marked a third, all within the space of an hour.