Walking in a country meadow one spring evening at dusk, you hear what sounds like thousands of tinkling sleigh bells. As you approach a pond, the sound grows louder, filling the air until you feel almost dizzy.
Sleigh bells? In March?
The sounds you hear are not bells, but male northern spring peepers calling for mates. When many peepers sing together, their high, piping whistles blend to sound like sleigh bells. If you had a flashlight, you might be able to spot some of the frogs, but they are only an inch long, and they hide themselves well.
Spring peepers are members of the treefrog family. Their toes have small, sticky pads that help them climb on low-growing plants. They also cling to grass blades and weed stalks near water's edge.
All frog and toad males, regardless of species, have breeding voices they use to attract mates. To make their calls, male toads and frogs close their mouths and noses and force air back and forth from their lungs to their mouths. The air passes over the vocal cords and creates a distinct sound. Balloon-like voice sacs help amplify the sounds. Some frogs can even call under water.
As amphibians, toads and frogs live part of their lives in water and part on land. When young, they live in water as tadpoles. As they mature, they grow legs, but their gills and tail disappear. They also develop lungs, allowing them to breathe air and spend most of their time on land.
Frogs resemble toads, but there are essential differences. Frogs have smooth, wet skin, while a toad's skin is dry and bumpy. Frogs have tiny teeth, but toads are toothless. Frogs have longer hind legs than toads. Frogs jump, toads hop. Frogs lay their eggs singly or in clumps, while toads lay long strings of eggs.
Because they eat a variety of insects, spiders and worms, frogs help control destructive insects. However, scientists are concerned that frogs are decreasing and are beginning to study them more carefully.
Many frogs are small and not easily seen. One of the world's smallest, Sminthillus limbalus, lives in the tropical forests of Cuba. It is only 1/2-inch long. The world's largest species is the Goliath frog, which lives on the west coast of Africa. It grows up to 14 inches long and can weigh five pounds.
On spring and summer evenings, you usually can hear frog tunes near marshes, meadows or woodlands. Ponds and creeks in parks are excellent places to hear them. With practice, you can learn to identify the frogs you hear without ever seeing them.
If you hear a loud, deep call sounding like, "Jug-o-rum, Jug-rum," coming from the edge of a pond, you are probably hearing a bullfrog. Missouri's largest frog, the bullfrog sometimes reaches eight inches long. They are easy to find at night because their eyes reflect in the beam of a flashlight.
Raspy sounds resembling those made by plucking a loose banjo string are likely coming from green frogs. These two- to four-inch frogs are common in Missouri, but they are hard to spot because they usually hide in vegetation or rock crevices.
If you hear steady, descending snores, you are probably listening to pickerel frogs. These two- to three-inch frogs are common in southern and eastern Missouri. Female pickerel frogs must find these snoring sounds pleasant, for they come a-jumping to locate the deep-voiced males.
Northern leopard frogs calls make a bit of a snoring sound, too, but it has an ascending pitch, much like that of a revving motorboat engine. These two- to four-inch frogs live in marshes, grasslands and high mountain meadows. In summer, they often wander far from water. This species is rare in Missouri, occurring only in a few counties in northwestern Missouri.
You can imitate the call of the western chorus frog by running your fingernail over the teeth of a pocket comb. These one-inch frogs are abundant in prairies. They also inhabit damp woods, marsh edges and the grassy areas along ditches, streams and farm ponds. They often can be found in cities and suburbs, too.
The mating call of the inch-long Blanchard's cricket frog, which can be heard all summer, sounds like pebbles being clicked together -"gick, gick, gick, gick." The clicks usually start slowly and then gain speed. Blanchard's cricket frogs can be found statewide near the edges of ponds and streams.
Many other frogs sound off in spring. What sounds like ducks quacking at night may instead be the hoarse, clacking sounds of the rare wood frog. Illinois chorus frogs make clear, bell-like peeping noises when they call alone, but when in chorus they sound more like a squeaky pulley wheel.