Blane Klemek: Amphibians that call Minnesota home
While turkey hunting recently near Detroit Lakes, I’ve enjoyed the chorus of frogs emanating from the recently “thawed out” wetlands.
Some basins still have ice, but most are ice-free now. But in all cases, three species of frogs — wood, chorus, and spring peeper — are vocalizing loudly as they try to make up for lost time.
Minnesota is home to many species of amphibians — frogs and toads — also known collectively as anurans. Amphibians, derived from the Greek word “amphibious,” which means, in part, “living a double life,” come in two distinct life forms here in the Northland: salamanders, and frogs and toads. In all, five salamanders and 14 frogs and toads call Minnesota’s waters and woods home.
What is fascinating about amphibians is that parts of their lives occur in the water. Yet, as with so many things in nature, there are exceptions. In the case of the mudpuppy, their entire lives are spent in water. These salamanders, unlike the land-loving adult form of the tiger salamander, live their entire life underwater, complete with external gills.
Frogs and toads native to Minnesota — and all of Minnesota’s amphibians for that matter — lay eggs. The eggs of frogs and toads hatch in the water and subsequently become tadpoles — those fish-like, gilled creatures that eventually undergo the amazing transformation of becoming a frog or toad. That two such radically different life forms and lifestyles exist for one species of animal is nothing short of miraculous.
Basically, frogs are divided into two groups while toads comprise their own. True frogs, which are the smooth-skinned, narrow waisted and long legged species, include bull, green, mink, northern leopard, pickerel and wood frogs. The males of each species have their own distinct voice readily identifiable. Females can also vocalize, but usually can only emit distress calls and do not call as loudly or frequently as do springtime male frogs.
The other group of frogs, treefrogs, includes western chorus, boreal chorus, Cope’s gray tree frog, gray tree frog, spring peeper and cricket frogs. Treefrogs, as their name suggests, are adept at climbing trees. Special pads on their toes enable these petite yet plump-looking frogs to adhere to most anything vertical, even glass windows.
The unmistakable voices of the Cope’s and gray tree frogs, which are typically produced while perched within the branches of trees and shrubs, is a bird-like trill. Some years, their chorus can be nearly deafening. And if your house happens to be near a yard light and suitable wetland, well, chances are good you’ll enjoy visits by these anurans. Treefrogs have learned bright lights attract plenty of insects and that windows and siding afford ample space for which to capture them.
The third group of anurans is the thick-skinned, warty and dry looking toads (no, you can’t get warts from a toad). Toads happen to be one of my favorite amphibians. The males of these sluggish and affable creatures emit beautiful nighttime melodious trills in late spring as they call for mates. You’ll frequently discover toads in your flower beds, in tall damp grasses and in vegetable gardens where they search for prey such as grubs, worms, beetles, moths, flies and slugs.
Three species of toads exist in Minnesota: the Canadian, American, and Great Plains toads. The musical trills of each toad are distinctive, though the trill of the male American toad lasts the longest, sometimes over a half minute per call. Females of each species lay massive numbers of eggs, more than 20,000, and are among the most prolific egg layers of any Minnesota anuran. Of interest are the eggs of Great Plains toads. Their eggs, which are laid in ephemeral wetlands, ditches and flooded fields, hatch in only two days. And in just six week’s time, their tadpole babies emerge as adults.
Right now, the loud, duck-like quack-calls of wood frogs can be heard throughout countryside wetlands. These are the first frogs to welcome spring, and are usually followed immediately with vocalizing chorus frogs and spring peepers (but not this spring!). After this trio, expect to hear leopard frogs, and then toads and tree and mink frogs. Green frogs, those big green-colored frogs of large lakes, will be vocalizing in late spring and on into the summer.
Come to think of it, this reminds me of something that’s fun, educational and valuable. For those of you interested in volunteering your listening ears, your DNR Nongame Wildlife Program sponsors a statewide study of frogs and toads — and you can help. For over a decade now, volunteers have been collecting data by simply listening and identifying species of frogs and toads along specific routes throughout Minnesota.
By visiting your DNR website — www.dnr.state.mn.us — you can learn about how you can participate in the annual Minnesota Frog and Toad Calling Survey.
If you’re like me, the sounds of frogs and toads are a welcome sign that spring has sprung: the quacks of wood frogs, the peeps of spring peepers, the snoring of northern leopard frogs, the trills of toads, and the raccoon-like calls of gray tree frogs and others. What would our marshes be like without them? For starters, it would be a less pleasing spring and summertime experience as we get out and enjoy the great outdoors.
— Blane Klemek is a Minnesota DNR wildlife manager. He can be reached at firstname.lastname@example.org