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Reptiles and Amphibians of Yosemite National Park (1946) by Myrl V. Walker


TREE TOADS

Another of our interesting amphibians is the small tree-toad or tree-frog which is so often heard but seldom seen by the average person. Although the tree-toad is the smallest of all the amphibians found in Yosemite National Park, it is, nevertheless, one of the most interesting. The tree-toad does not spend all its life in trees, as one might infer from the name. Instead the tree-toad must go to ponds and streams to deposit eggs which hatch into tiny tadpoles that spend two or three months in the water before being able to maintain themselves on land. Of all our toads and frogs, the tree-toad is the only one equipped with the necessary tools to climb up into trees or bushes. This it does quite often as an adult and it may occasionally be found sitting on a leaf patiently waiting for some insect to come along. This special equipment consists of small round sucker-like discs which it has on all its toes, both fore and aft, and these make it possible to climb with ease; in fact, it seems to delight in walking up the glass panes of the aquarium jar, and out, if the cover is not always kept in place.

But the most interesting feature, as far as our amphibians are concerned, is the fact that it can change skin color to match the color of the background; hence, it is quite inconspicuous among the low leaves of vines or shrubs. Only when it visits the water holes in the spring, or after sudden rain storms, are we aware of its presence, but at that time it puffs out its throat and sings a song no one can mistake, a non-melodious “crack-it” which is all out of proportion to the size of the individual making the noise.

Although the tree-toad is an expert in the art of camouflage, there is one color feature of its anatomy that seems to change very little, and that is the dark black line or bar that extends from the snout through the eye and back through the ear membrane nearly to the shoulder. This tell-tale mark is always present for ready identification of the little tree-toad.

PACIFIC TREE-TOAD
Hyla regilla

In one respect the Pacific tree-toad differs from all other of our amphibians, for it seems to pay no attention to life zones, changes in elevation or forest cover, but is found from the lowest elevations in the park up to over 10,000 feet. No other amphibian has been able to adapt itself to such

PACIFIC TREE TOAD
[click to enlarge]
From Slevin: The Amphibians of Western North America. Courtesy of the
California Academy of Sciences
PACIFIC TREE TOAD
divergent life zones or habitats. Even in areas where conditions seem to be extremely arid, it manages to absorb enough moisture from the early morning dew, or from the leaves and foliage, so as to keep its skin moist and functioning properly.

The tree-toad is small and usually measures less than two inches in length, and is always readily recognized by the small rounded discs on the ends of all toes. The color is variable, being gray, green, or nearly black. The underside is less variable, being nearly white and unspotted, but with a blackish patch on the throat of the males. They are usually found singly except during the spawning season.

Tree-toads have been taken on the floor of Yosemite Valley, in the pools along the Merced River, and even around the houses where watering of lawns and shrubs provides an attraction. They have been taken at Tuolumne Meadows, Yosemite Research Reserve, Lukens Lake, Yosemite Falls, Miguel Meadows, and even on the back porch of the Museum. They seem to be abundant nearly everywhere, but it takes quick, keen eyes and a little knowledge of tree-toad habits to be able to locate them at the various seasons of the year.



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