Just Blending In
Nearly weightless tree frogs sit on leaves awaiting insects
Published August 6, 2022, in the McAllen Monitor
Story and photos by Anita Westervelt, Texas Master Naturalist
Not all tree frogs live in trees. In the Valley, though, the common Mexican tree frog (Smilisca baudinii) usually lives in trees near a water source. Like most other frogs, tree frogs are nocturnal. They sleep during the day in tree holes, under loose tree bark or sit in trees, blending in, weightlessly sitting on leaves or thin branches.
Another favorite Valley habitat for these small frogs is in banana plants, especially during a dry period. Tree frogs like humidity, which make banana plants attractive because the trunk, called a pseudostem, is a sturdy stalk of overlapping leaf sheaths, consisting mostly of water.
Although small, the common Mexican tree frog is the largest tree frog native to the United States -- and it’s just barely here at all; its most northern native range is the Lower Rio Grande Valley where small, isolated populations have been found in Cameron and Hidalgo counties.
Tree frogs have the typical frog shape, where the head is broad, flat and indistinct from the body. Common Mexican tree frogs are chunky, with rather short legs. Females are slightly larger than males at three and one-half inches long; males measure nearly three inches long. Frogs are measured snout to vent, meaning the tip of the animal’s nose to the posterior opening at the base of the tail.
Common Mexican tree frogs vary in color and markings from tan to brown, gray or green; some may have the classic pattern of darker colored, irregular patches on the back; their underside is typically light gray or white. They can change color depending on the circumstances. Regardless the color or pattern, the legs will show a distinctive banding. They travel via land to water to mate. They move by leaping, using forelimbs and hind limbs.
The most distinguishing feature of tree frogs is that the last bone in their toes is claw shaped. Many also have extra skeletal structures in their toes. Disc-shaped adhesive pads on their fingers and toes help them climb about in trees and land on leaves where they sit and wait for insects to pass by.
Common Mexican tree frogs have a row of warts along the lower arm which distinguishes them from other species. They are insectivores with exceptional eyesight for nocturnal hunting. They eat crickets, flies, mosquitoes, ants, worms, spiders, beetles, moths and other small invertebrates, ambushing prey with their long, sticky tongues.
In the early morning hours before dawn, these little tree frogs, as well as other frogs, toads, and house geckos, are frequent visitors around a moth sheet and black light setup, snacking on the variety of insects and moths attracted to the light.
Tree frog predators include raccoons, squirrels, hawks, fish, birds, some snakes and possibly bats.
Also called Mexican smilisca, the species is listed in Texas as threatened, although there is no federal listing. South of the border, through Central America to mid Costa Rica, the frog is very common and classified in the least concern for extinction category.
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Websites helpful in writing this article were Amphibiaweb.org, National Wildlife Federation www/nwf.org, and kidadl.com.