Thursday, October 18, 2012

Tree Frogs

While at my son's house last weekend, a tree frog climbed up onto one of their windows. Three pictures I took are included below.  So I decided to learn more about these cool amphibians.

There are more than 3400 species of frogs and toads worldwide, with the majority living in the humid tropics. Michigan can boast only 13 species, but they are an important part of the State's wildlife heritage.

Frogs and toads, along with the salamanders, are members of the class Amphibia. Amphibians are characterized by a life cycle which begins with an unshelled egg laid in water, the egg hatches into a fish like, gill breathing larva (called a tadpole or polliwog in frogs and toads), followed by the transformation of the larva into an adult. During this transformation, the larva gradually develops legs, lungs, and other modifications for life as an air breathing adult capable of living on land. Most amphibians have rather thin skins through which they can "breathe" and absorb or lose water. Because of this, they prefer to live in moist or wet habitats.

How can you tell a frog from a toad? It's been said that a toad is just a lumpy frog! Toads do have thicker, more warty skins compared to the smoother skin of most frogs. Toads are adapted for drier conditions than frogs, though they spend much of their time burrowed into moist soil during times when the air is drier. Toads have shorter hind legs than frogs, comparatively speaking, and move in short hops or simply walk instead of making long leaps.

Michigan has two species of "true" toads, the American Toad and Fowler's Toad. Some species are hard to fit into either category. For example, Cricket Frogs have a warty skin, and the Gray Tree Frog (often called a "tree toad") spends much of the summer high in the trees away from water. The pictures above are of a Gray Tree Frog.

Most species pass the winter in a dormant ("sleep like") state underwater, either burrowing into mud, or just sitting on the bottom in ponds and swamps. Toads burrow deep into woodland soil.

From a human standpoint, frogs and toads are extremely beneficial animals. Their springtime choruses are a pleasure to hear, and most people enjoy seeing them, whether in wetlands or suburban gardens. Adult frogs and toads feed largely on insects, and destroy vast numbers of insect pests every year. It has been estimated, for example, that a single Cricket Frog an increasingly rare species in Michigan can consume about 4800 insects in one year. A hundred frogs would thus eat about 480,000 insects, a thousand frogs perhaps 4.8 million insects, and so on.

Tree frogs have large, sticky toe pads. Color can change gray, green, or brown, according to environment or activity.

HABITAT: Woods, swamps, backyards. Able to climb vertically, or move horizontally, with specially adapted toe pads.

BREEDING: May, in woodland ponds. Males call from low vegetation, near or over water. Eggs in small cluster. Transformation of tadpoles by mid to late summer.

VOICE: A short musical trill. Often heard before and after breeding season on warm nights. Trills of the two species sound different.

RANGE AND STATUS: Common statewide.

NOTES: They will often cling to windows of houses at night.

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