WILDER SIDE OF OAKLAND COUNTY
April is National Frog Month; it’s well underway and things are hopping. Frogs do some mighty strange things, at least in the eyes of humans. Knowing facts about the lives and abilities of frogs will enhance your frog month celebration. That’s what this special blog post is all about. Then it’s time to trek off to a vernal pond in the woodlands, or perhaps lean against a tree at the edge of wildland marsh with a favorite frog-loving friend to enjoy a fantastic frog symphony in the dawn’s early light, or twilight. This link from a 2014 National Wildlife Federation blog in celebration of National Frog Month, has fun frog activities for young children. I won’t tell anyone if you read that link in order to glean more information for yourself about the long-leaping, bug-eating, swamp-singing amphibians that inhabit Oakland County.
Amphibian means “two lives”, referring to the fact frogs begin their life in water before hopping about the edge of wetlands. In scientific terms, “an amphibian is a cold-blooded vertebrate animal that is born in water and breathes with gills. As the larva grows into its adult form, the animal’s lungs develop the ability to breathe air, and the animal can live on land. Frogs, toads, and salamanders are all amphibians. The word amphibian comes from the Greek word amphibious, which means to live a double life. The noun amphibian has its roots in the words amphi, meaning of both kinds, and bios, meaning life.” It’s easier to explain it to kids in a simplified fashion. This should work: Frogs start out as eggs laid in or near water. In their next stage, the eggs turn into creatures called tadpoles. The tadpoles stay in the water and breathe through gills until they grow legs, develop lungs and climb out of water as frogs.
Frogs do not ”croak” because they are happy. The males vocally establish territory and sing to lure lady frogs. Spring Peepers and Chorus Frogs started singing last month, but as shallow waters warmed, the creaky duck-like clatter of Wood Frogs and prolonged rumbling call of Leopard Frogs kicked in and reached top volume last week. Gray Treefrogs remain silent-for now. But if a hot and humid afternoon, or warm weather thunderstorm rumbles into town, treefrogs may explode into their rather harsh short insect-like trilling song from the branches of trees and nearly impenetrable thickets.
Frog tongues are attached to the front of their mouths rather than attached way back in the mouth like the tongue you and I have. Our tongues are not good at catching bugs. But when a frog sees a squirmy insect, wiggly worm, or juicy bug it throws its sticky tongue out of its mouth in a lightning fast maneuver and wraps it around its prey. Then it snaps back in and all but throws the food down the throat.
Did you know that frogs use their eyes to swallow? Well, they sort of do that. When a frog gulps down a meal, it squeezes its large eyes closed. That muscle movement sinks the eyes down into the head and that helps push the still squirming food down the throat. As you may have guessed, frog eyes excel at spotting movement of both prey and predators, even when everything but their eyes and nose are under the surface of the water.
Frog skin, unlike toad skin, needs to be moist. Frogs do not drink water, but they do absorb water through their permeable skin. Because they absorb water through their skin, frogs are excellent indicators of chemical contaminants in water. Dr. Ruth Marcec is the director of the National Amphibian Conservation Center at the Detroit Zoo and is acutely aware of the plight of many species of amphibians, including frogs, and works with rare amorous amphibians and “encourages” them to breed. She was quoted last month in the Detroit Free Press (March 17) saying, “If you combine all the endangered mammal and birds, that still doesn’t add up to the percentage of amphibians that are threatened and endangered.” Consider frogs an early warning system of our wetlands. When frog populations die, we should be concerned. For in the world of nature all things are connected.
As temperatures soared over the 80 degree mark last Saturday, Green Frogs and Bullfrogs were lazily swimming the shallows of small lakes and ponds across our county. Some tentatively started their courtship songs, perhaps in attempt to catch up with the early bird songsters of the frog world, Spring Peepers, Wood Frogs and Chorus Frogs. The unseasonal warmth also stirred frog predators into action, with the list including Great Blue Herons, Egrets and the Northern Water Snakes, three species on the Wilder Side of Oakland County that take gluttonous delight in National Frog Month.
We all have our favorite frogs. These five are mine:
National Geographic describes Spring Peepers perfectly, “Spring peepers are to the amphibian world what American robins are to the bird world. As their name implies, these frogs begin emitting their familiar sleigh bell chorus right around the beginning of spring. Found in wooded areas and grassy lowlands near ponds and swamps in the central and eastern parts of Canada and the United States, these tiny, well-camouflaged amphibians are rarely seen. But by mid-March the crescendo from amorous males is for many a sign that winter is over. Spring peepers are tan or brown in color with dark lines that form a telltale X on their backs.” Here’s another fact of interest. Their Latin name, Hyla crucifer, is derived from the cross, or “telltale X” on their backs.
Gray Treefrogs spend much of their time in shrubbery and trees and sometimes use their suction cup like toe pads to climb up the outside of a window pane. They are not the Peeping Toms of the frog world, but they do know opportunity. When the light from inside the home attracts bugs, the treefrogs climb up for an easy meal. The scientific name for the gray treefrog, versicolor, is derived from Latin and means ‘variable color’, which relates to this species’ ability to change color to blend into their habitat. Gray Treefrogs, may be shades of gray, bright green, brown or a combination of colors.
Green Frogs are the second largest species of frog found in Oakland County and are denizens of the ponds and lakes of our county. They are the species most seen, most loved, and most often chased by children as they sit motionless on the pond’s edge. The unseasonable warmth of the past weekend had one Green Frog at a pond near me struggling to sing. The sound is accurately described as a banjo string being plucked. Mine sounded a bit off-key. But all things may work out, for the early bird frog gets both the worm, and may lure a mate.
Bullfrog can be eight inches long and are the largest species of frog in North America. These pop-eyed inhabitants of large ponds and wetlands are more than a mouthful for some predators and occasional turn the tables and eat snakes, small birds, mice, voles, and other frogs. They are well-known for the deep baritone call which is heard most often on sultry summer days and nights and is often described as “Jug-of-Rum, Jug-of-Rum.” The embedded link from National Geographic has great information on these giants including an excellent recording of their song.
Toads? Isn’t this National Frog Month? According to the University of Michigan’s Museum of Zoology, there is no scientific distinction between frogs and toads. Frog and toads both belong to the Anura order, but are found in different families. The National Wildlife Federation explains the difference to young children this way, “Basically, toads are frogs that spend most of their time on dry land. As a result their skin is rougher, which helps camouflage them in the knobby world of dirt sand and leaf litter.” That simple explanation works for me too. Life can be tough for toads, a species that is renowned for its lack of beauty, at least in the eyes of some beholders. Last Sunday, the toads on the Wilder Side of Oakland County jumped the gun on when they normally emit their loud prolonged high-pitched trills. The trills of the male toads attract the female toads, human frog lovers and predators. Take a look at this video to listen in.
Hognose Snakes have a non-reciprocating love affair with toads. Toads are their favorite entrée. These non-venomous snakes that can flatten their head like a cobra are rare in Southeast Michigan but thrive in some sandy areas of Michigan, including South Manitou Island, where I photographed this hognose last year waiting to ambush a toad, perhaps as its celebratory feast for National Frog Month. Other frog predators are Northern Water snakes, Egrets and Great Blue Herons.
Jonathan Schechter is the Nature Education Writer for Oakland County Government and blogs weekly about nature’s way, trails, and wildlife on the Wilder Side of Oakland County.