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Annual Anuran Chorus Tunes Up

Spring 1997 Newsletter

The soft spring music of frogs and toads has long begun, and their melodies are balm to the soul. It is a comforting reminder that spring really is here — regardless of what the weather man reports.

But who sings what? And where? And how can you tell a frog from a toad? And do you care? If so, read on. Although I don't qualify as even a pseudo-scientist, I do have an ear for music. So hang in there with me as I endeavor to make this subject as simple as I can.

Toads and frogs, Order Anura, are the most widely distributed of all the amphibians. There are nearly 3700 known species, and each species has its own distinctive mating call.

Illinois toads and frogs are mostly insectivorous and primarily nocturnal. Although some exist quite happily on land, they all require water to breed. Only males vocalize. Don't ask why.

Their calls have to do with territory, weather conditions, and self-defense. each spring, males begin their incessant calling to which the females respond in a few days. That's when all that clasping begins and tadpoles are made. (All right, it's called amplexus.)

Picture this common spring scenario: a few small children peering into a bucket full of squirming tadpoles. "What are they?" -- "They're tadpoles, silly." -- "I KNOW, but what ARE they?" -- "I dunno, they're too little to tell yet. We'll keep'em 'till they turn into something."

And usually they turn into a bucket of dead tadpoles. Returned to the water, they would develop into frogs or toads. Unless they were polliwogs or mud puppies -- or guppies. Let's clear that up first.

A mud puppy is an adult aquatic salamander. A guppy is a small popular fish which gives birth to live young. A tadpole is an amphibian in the larval stage which develops into a frog -- or a toad. And a polliwog is just another name for a tadpole. So -- let's keep going.

Toads are tiny. Frogs are larger. Except for the teeny weeny Little Grass Frog, Pseudacaris ocularis, which measures 7/16", and the huge Giant Toad, Bufo marinus, at 6".

As in all things, exceptions exist to confuse the learner. Short of having an illustrated field guide ever handy, it is pretty difficult to tell one from another. A suggested method is to identify their breeding calls.

A few years ago, Southern Illinois University at Carbondale conducted a pilot program to monitor the breeding status of frogs and toads. As I read through the volunteer instructional manual, I had to chuckle at the thought of all those people lugging flashlights, tape recorders, clipboards, field books, and mosquito spray, slogging around at night through watery habitats.

Oh well, somebody has to do it. Usually people like me. I was also amused at the manual's description of some less than musical anuran utterances, such as: metallic sounding 'tricks', in progressively more rapid cadence; a nail being rapidly struck with a hammer; a soft, snoring 'meow'; a snore and a chuckling sound. However, I am only going to include the more melodious listings in this survey.

There is only one common toad found locally, Bufo americanus, 2 - 3.5", the American toad. It likes a variety of habitats -- ponds, marshes, residential lawns and even ditches. This toad begins his musical courting in late April - May with a long 'whirring trill', so we know right off that this is "toad" and the other sounds are all "frog".

The earliest of lovesick anurans are the chorus frogs. Spring peepers, Pseudacris crucifer, 0.75 - 1.25", can be heard in late March - early April in shallow pools and ponds in woodland areas. Their call is, of course, a 'peep' or 'peep-er'. The western chorus frog, Pseudacris triseriata triseriata, 0.75 - 1.5", prefers woodland and prairies and will breed in any body of water, but rarely in rivers or streams. Theirs is a unique love song, sounding like a fingernail running along the teeth of a comb.

All chorus frogs are tiny and, obviously, it takes quite a lot of them to make a chorus. You probably have heard them already; they are usually the first spring vocalizers. Within days of the first spring thaw in late March, they are seeking to romance the females with their siren song.

Tree frogs have tiny toes equipped with adhesive discs. they are sometimes called tree toads, although why is uncertain, as they are not toads. Whatever, they are usually arboreal and breed in ponds or wetlands or near woodlands.

Their bird-like trills can be heard from early to mid-May through mid-June. Tree frogs and chorus frogs are very small and very similar, and you probably couldn't tell the difference between them -- unless you caught one of each and compared their toenails!

Short of that, you'll just have to stay confused about which is which. But! -- none of these are 'true frogs'. (See what I mean?)

True frogs, Family Ranidae, are very typical frogs, dependent on a watery habitat. This Family occurs on all continents except Antarctica. They are long-legged, narrow-waisted and rather smooth-skinned.

The Bullfrog, Rana catesbrina, 3.5 - 6", is our largest true frog with a record length of 8". Its aquatic needs can be satisfied by any permanent body of water, and its romantic needs are advertised in late May through August.

The female Bullfrog is able to make some occasional vocal sounds (another exception!). Some even scream when captured. Understandable, given the fact that the male's best attempt at wooing a sound described as a low, basso "vroom-vroom" which has always sounded to me like a sick cow.

The Green Frog, Rana clamitans, 2.25 - 3.5", is smaller than the Bullfrog and prefers heavily vegetated shorelines in shallow water. It is characteristically a frog of brooks and small streams. The throat of the adult male is bright yellow. The country & western crooner starts calling in late May through August, with a 'twang', or 'twang-twang'.

Incidentally, the Green Frog seems to be so in name only, as it varies more to brown than green -- except when it is blue, which means it is lacking in yellow pigment. This also can happen to Leopard Frogs, Rana pipiens, and Bullfrogs.

If it is starting to occur to you that identifying frogs and toads is confusing, it's because it IS confusing. A brief venture into the guide books will confuse you even further.

Some authors admit there are no hard and fast rules for telling the difference between them, and for lots of us, they all look alike. At least we don't have to be concerned with toads, since around here there's only good old Bufo americana.

So, let's go back to the basics we've all been taught. Generally, frogs are moist and smooth-skinned. Toads are dry and warty. Frogs leap on long legs. Toads hop on short ones.

Never mind the exceptions. And your mother was right -- you should wash your hands after handling a toad. It won't give you warts, but its skin gland secretions will irritate open cuts, eyes, and mouths.

However, it IS safe to kiss a frog -- it just might turn into a prince with a voice like Neil Diamond, singing "Spring is Here." Do venture out soon, and search for the crooner of your choice.

— Lou Strobhar