Michael Ellis

Now I want you to imagine that you’re on a movie set… there’s a soft rain falling, a couple embracing passionately on the porch of an antebellum mansion, the warm, heavy southern air envelops them, heat lightening flickers in the distance. The mood is nearly perfect but not quite; the director senses that something is missing– something he can’t quite put his finger on. What is it? WHAT IS IT? pause “FROGS” he shouts, “Frogs! We need croaking frogs! That’s it!” He sends the sound technician scurrying for frog sounds.

And so once again our hero, the Pacific tree frog, is called into action. It’s the most common frog sound heard in the movies. Whether the movie takes place in Britain, New Guinea, Texas or the Serengetti, if it’s shot in Hollywood it gets the local frog. Not coincidentally this is the most common frog in southern California. So, even though frog sounds vary around the world, for the sake of expediency this frog is the star of the night.

The tree frog’s scientific name, Hyla regilla, means “the little king of the woods” and I would add that they are also the little king of the fields. Every winter we hear loud and wonderful evening choruses throughout California. Wherever there’s standing water, whether it’s a roadside ditch, a farm pond, or even an outdoor hot tub, you’ll find uncountable numbers of males— singing, each one trying to attract a mute female. Imagine her dilemma: she chooses a mate based on his singing ability alone— one voice out of thousands. This is cutthroat (or is it frog throat?) competition.

Even though these little guys are easy to hear they are tough to see. They’re small; only 1 1/2 inches from nose to rear. And while they’re called “tree frogs,” I usually find them hidden in the grass. They get their common name from their great ability at climbing not only trees but even glass.

Pacific tree frogs range in color from brown to green with every shade in between and they can change those colors completely within ten minutes. They do this with special pigment cells on the skin called chromatophores. But regardless of its color phase each frog has a brown stripe running from the tip of the nose through the eye to the shoulder. When you see this field mark you’ll know it╒s a Pacific tree frog, even if you’re a novice frog watcher.

In addition to their loud calls males have olive throats and roughened toes that distinguish them from the quiet females. Also, the females are usually a bit larger. They mate in quiet waters–ponds, streams, usually not hot tubs. The male jumps on the female and uses his roughened toes to hang on to her slippery back. Then he discharges a cloud of sperm. She sheds her eggs onto submerged vegetation. Eggs and sperm then unite externally. They may repeat this act several times. The entire event takes 8 to 40 hours-or even longer!

The eggs hatch into little tadpoles in a very short time. Remember speed is critical when you depend on standing water that’s rapidly evaporating! Tadpoles breathe through gills and they’re vegetarians. After they grow for awhile they transform. It’s a miracle: their hind legs appear, their digestive tracts shorten, lungs replace their disappearing gills, and their tail is gradually recycled into other body parts. What was a tadpole becomes a little tree frog that hops from water onto the land.

The Pacific tree frog ranges all the way from British Columbia to Baja California and east as far as Montana. It lives from sea level up to 11,000 feet and is found many different habitats. It is the most widely distributed of any amphibian in the west and it’s done well in suburbia.

So the next time you are watching old reruns of MASH and see Major Houlihan and Frank trysting in the “Korea” night, remember it’s our very own Pacific tree frog that serenades them, the same one that’s in your backyard.

This is Michael Ellis with a Perspective.



Posted on

December 1, 2010