Frogs!

Off and on rainy days with warm(er) temperatures have really set the frogs in motion here.  I sat on an upended bucket by one of the ponds in the backyard and trained my binoculars on the pond’s edge, hoping to finally locate those tiny little creatures that were making that hugely loud racket.

Eventually, by trying to ignore the loudest chirpers, I could distinguish three different types of calls, all at different pitches, frequencies, and volume.  Finally, by staring at the water where I thought the calls were coming from (this takes sound localization ability, which apparently I am lousy at), I found the frogs making them.

Leopard frogs made very low intensity calls, very infrequently, and I couldn't really see where the sound was coming from (no obviously inflated pouches).

Leopard frogs made very low intensity, low pitch calls, and call very infrequently.  I couldn’t really see where the sound was coming from (no obviously inflated pouches).

Wood frogs sit horizontally in the water Ilike the leopard frogs, emitting sort of a quacking call that sounds like it should be coming from a duck.

Wood frogs sit horizontally in the water, like the leopard frogs, emitting sort of a quacking call that sounds like it should be coming from a duck.  Dark bodies, striped legs, and a black mask over the eyes outlined with white stripes — make this frog quite attractive.

wood frog, Rana sylvatica

Here the wood frog has inflated its vocal sacs during its "quack" call.

Here the wood frog has inflated its vocal sacs during its “quack” call.  When they do this, the water around them shows disturbances in concentric circles, making them a little easier to find in the pond (if you have bad sound localization ability).

Wood frogs are found almost everywhere in central and eastern North America; they are one of the first frogs out in the spring, as soon as the ice melts off the ponds.  They are unique in that they tolerate being frozen solid over the winter, as they “hibernate” in a state of suspended metabolism under the leaf litter.  Click here to view a short video of wood frogs calling (in Minnesota).  And here is an amazing video of Wood Frogs defrosting from their frozen winter state.

By far, the loudest, shrillest, and almost deafening calls were coming from the Boreal Chorus Frogs (Pseudacris maculata), which were almost impossible to find, mostly because I was looking in the wrong places.  They were sitting at least 3 feet from the shore, out in the submerged vegetation, oriented vertically, with their head, vocal sacs and abdomen out of the water.  Perhaps the volume of noise from multiple frogs confuses predators as well.  Are herons and egrets immune to this racket?

Even maximum telephoto didn't bring these tiny, one-inch Chorus frogs into view.

Even maximum telephoto didn’t bring these tiny, one-inch Chorus frogs into view.  

So, I moved to a better viewing spot, sat, and waited until they got used to my presence, and then got closer-up views of a calling Chorus Frog.  These frogs (once you see them) are easily distinguished by the three longitudinal stripes down their backs.

The cricket-like call is emitted through the larynx (voice box), but is amplified by vocal sacs.  The body cavity of the frog swells when air is inhaled through the nostrils, and the vocal sac shrinks.

The cricket-like call is emitted through the larynx (voice box), but is amplified by vocal sacs. The body cavity of the frog swells when air is inhaled through the nostrils, and the vocal sac shrinks.

Then, the frog contracts its muscles to expel the air during exhalation through the larynx, enlarging the vocal sac, and producing a vibration that amplifies the sound.

Then, the frog contracts its muscles to expel the air during exhalation through the larynx, enlarging the vocal sac, and producing a vibration that amplifies the sound.

If you haven’t had the pleasure of standing next to a group of calling Chorus Frogs, you can view a short video here.  These tiny frogs can emit sound at nearly 90 decibels, which is about as loud as the human ear can stand without damage, about the same as standing next to a truck without a muffler.  And, they call continuously for hours and days on end.  Now how is that for amazing!

For good photos and descriptions of MN frogs and toads, you can click here.

11 thoughts on “Frogs!

  1. Lovely photos, Sue! I really enjoy frogs, too. I’ve had leopard frogs colonize ponds in several of my gardens. They can leap farther than just about any frog I’ve ever seen, and ours look pretty much like yours. But I have never seen ANYTHING like the frozen wood frog! That is utterly amazing! Thanks for including the video. If I hadn’t seen it with my own eyes, i probably wouldn’t have believed it. (Naturally, it doesn’t get cold enough here in central Florida for our frogs to freeze. Or if they do, they do NOT come back again.)

    A great post, as always!

  2. Fascinating post. I didn’t quite understand how the vital organs could survive at an ambient temperature of minus three even if they avoided ice crystal formation damage by drawing the water away. I bet somebody somewhere is trying to work it all out!

  3. We have wood frogs here (in NH) in abudance. We also have leopard frogs, but they are kind of rare – I’ve never seen one, and I understand that if I ever do, I should call Fish & Game so they can come out and verify it. We have spring peepers – a species of chrous frogs (same genus as yours, but different species, but I can’t think of its name in latin). They have crosses on their backs. Like yours, they are very loud, but not easy to see!

    • There are lots of spring peepers around, but not in this particular pond. The spring peeper has been added to the chorus frog genus now, so it is Pseudacris crucifer (for the cross on its back). I wasn’t aware that leopard frogs have become so rare in the northeast. Interesting.

      • I was thinking it would be something like crucifer, but the Pseudacris part was confusing me into thinking THAT was the part that meant cross. I could have just looked it up!

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