Archive All Issues January 2002

The State Amphibian

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The Arizona tree frog claims a loose relationship to celebrity frog Kermit.

Featured in the January 2002 Issue of Arizona Highways

Spotting an Arizona tree frog in the wild must be done in late spring and summer when the little guys emerge from under rocks and logs to feed and breed.
Spotting an Arizona tree frog in the wild must be done in late spring and summer when the little guys emerge from under rocks and logs to feed and breed.
BY: Dennis Lengone

on nature focus The Whole Truth About the ARIZONA TREE FROG, the State Amphibian

"IT'S NOT EASY BEING GREEN," LAMENTS Kermit the Frog. The Muppet character's close real-life relative, however, the Arizona tree frog, might disagree as it glistens with a moist verdant skin, hiding near wet meadows and shallow grassy pools. It exhibits not only green but occasionally colors ranging from gold to bronze. Kermit might just be green with envy.At night, take a flashlight into the high country at 5,000 feet and higher perhaps along the Mogollon Rim, in the Coconino, Apache-Sitgreaves, or Coronado national forests and you might catch a glimpse of the little tree frog before it scurries away. But don't count on it. Not only is this creature nocturnal, it measures less than 2 inches long. And during most of the year, the tiny frog hibernates under rocks and logs. Only from May through September does it emerge to breed and feed, still hiding much of the time under groundcover and in trees.

Though designated the state's official amphibian in 1986, the tree frog suffered a misidentity for years, according to Brian Sullivan, a biology professor at Arizona State University West. "We have been referring to this species as Hyla eximia, native to Mexico," he said. "Not until recently have identification techniques improved enough to differentiate the Mexican tree frog from our Arizona resident, whose true name is Hyla wrightorum." Subtle differences in mating patterns and calls were discovered.

A doctoral student of Sullivan, Eric Gergus has used DNA analysis to conclusively separate Hyla wrightorum as a unique species, actually affirming suggestions made decades ago that both species existed.

Nevertheless, some scientific literature still refers to the Arizona State Amphibian by its old genealogical name. Mike Sredl, resident herpetologist of the Arizona Game and Fish Department, said: "In our department, we use names from a standard biology manual. Unfortunately, until a new edition is published, the Arizona tree frog will retain its present name with us." He added that scientists are slow to change. To some researchers, the name change has been controversial, and adoption of the change will wait until studies are reviewed.Sredl motioned to an aquarium in an adjoining office. Inside, three cute green critters hunched in hollowed tree branches. They stared with bulging omnidirectional black eyes. I wanted to pick one up. Almost as if reading my mind, Sredl told me the critters make appealing pets.

Like fish, the tree frog is an ectotherm, or cold-blooded, meaning its body temperature fluctuates with its environment. But then, like any land inhabitant, it can navigate and breathe on dry ground.

Tree frogs and other amphibians make good indicators of our environment's quality because at all their life stages they are particularly sensitive to toxic substances, according to a conference of worldwide researchers. For this reason, environmental biologists watch their survival and health closely. The Arizona tree frog also benefits the environment by keeping insect populations under control. We can thank our state frog, for instance, for helping to keep pesky mosquito populations down.

According to Game and Fish, our amphibian thrives in its home state, unlike some of its beleaguered relatives, but the reasons are not entirely clear. One helpful factor, however, is the required license limiting capture to only 10 frogs a year. The rule is aimed at restricting overzealous researchers, those wanting tree frogs for pets or as food for their larger pets.

But man is not the only hunter of the frog. The amphibian is prey to various neighbors. Sredl says the tiger salamander, which feasts voraciously on the tadpoles in water, is a major predator. As the frog matures, its survival depends on a keen lookout for raccoons, snakes and large insects. And where man alters the frog's environments, such as ponds and rivers, or removes leaves, logs and trees the natural cover of grassy land - the tree frog population is jeopardized most. In 1986, Arizona elementary school children chose the state tree frog to promote environmental awareness. Its larger cousin, the "green tree frog," basis for the famous Muppet character Kermit, has been adopted as Louisiana's State Amphibian. But perhaps Arizona's own smaller frog, with its alternate yellow, bronze, gold and green colors is uniquely appropriate for the state known for its multicolored flag.