Most everyone recognizes frogs. Frogs, like salamanders and newts, are amphibians. Unlike salamanders, they have made a major evolutionary detour from the body plan of their ancient ancestors. The hind legs of frogs are much larger than the forelegs and the tail has disappeared. This allows a new mode of locomotion, namely jumping, an effective method to elude their many predators. Because they leave the ground to get around, using scent to communicate with each other is not a viable option, as it is for salamanders. Consequently, frogs are among the most vocal of vertebrate animals (birds fly, so they vocalize a lot as well!). Frogs in New York fall into four major groups (families) linked by anatomy and other features of their biology.
Toads are frogs that, due to the nature of their coarse dry skin, are adapted to spend most of their life on land. We have three kinds in two different families. The very common American toad is easily recognized by the warts all over its back and sides and by a pair of large bean-shaped glands are located just behind the head. These glands produce a mild poison that the toad stores in its bladder. When handled, toads will produce a copious urine with enough of this foul-tasting toxin to deter most predators. As a consequence, toads do not need to be good leapers to escape their enemies. Toads begin breeding late in April when males begin producing their long, rather musical trill. One can imitate this call by whistling and humming at the same time. Toads use all sorts of water bodies to deposit their long strings of eggs. Since hatching and tadpole development can be completed in as little as four to six weeks, toads often use temporary bodies of water to deposit eggs. This may include large puddles and deep tire tracks that hold water.
One representative of the spadefoot toad family reaches New York, although they are restricted to the sandy-soil pine habitats of Long Island and the Pine Bush near Albany. Spadefoots can be recognized by their rather smooth skin, vertical eye pupils, and the dark hard patches of skin on their toes used for digging. They spend much of their time underground and are most active on the surface at night following heavy spring and summer rains.
The only true tree frog of New York, the gray treefrog, is common over the entire region. It is most often observed in late spring and early summer when the males make their characteristic loud trilling calls. Calling sites are usually in the lower branches of trees near the water's edge. They possess large round toe pads that enable them to maintain their grip even on vertical surfaces. Adults are mostly gray with black splotches but they can change their color pattern to a degree and may appear bright green to silvery. A flash of yellow is found on the undersides of their legs.
The spring peeper is clearly one of the most common vertebrate animals in New York, found in nearly all forested habitats within a few miles of standing water. Although few have actually seen one, nearly everyone has heard the distinct, and very loud, peep these tiny frogs produce. Despite their inclusion in the treefrog family, peepers are rarely found in trees. Outside of the breeding season they may be found leaping along the forest floor in search of insects. And what a leap it is, nearly 50 times their inch and a half length! In the breeding season, male peepers gather in the weedy vegetation at the edge of ponds to call and attract females for mating.
Eggs are attached singly to underwater plants and hatch within a week. After about 45-60 days, depending partly on water temperature, the tadpoles emerge from the water and inhabit the leafy litter of the forest. Other members of the treefrog family include the northern cricket frog, found in a few areas south of the Catskills, and the western chorus frog, which occurs along the western Lake Ontario plain and the Watertown area.
The bullfrog is the clear winner in the size department among New York frogs, attaining lengths of 7 inches from snout to tailbone. The low frequency "jug-o-rum" call they produce is familiar to all May and June visitors of the region's lakes and ponds.
One of the most common mid-sized frogs across New York is the green frog. They can be superabundant in marshes, ponds, lakes, and quiet backwaters of streams if their insect food supplies are also abundant. Male green frogs, like those of bullfrogs, have visible eardrums on the side of their heads that are bigger in diameter than their eye. The eardrum of females is smaller than the eye. Green frogs make at least six vocalizations, but the most often heard is the advertisement call of the male. It has been compared to plucking a banjo string.
Mink frogs may be found in the colder waters of northern New York, primarily in the Adirondacks. They are small frogs that at first glance are easily confused with the much more common green frog. Careful examination of the spotting pattern across the folded hind limbs, which appears random in mink frogs and continuous in green frogs, will distinguish the two. The presence of a strong musky odor on your hands after you release one will clinch the identification as a mink frog.
Before winter is officially over, and often while there is still ice on the ponds, a sound like quacking ducks may be heard in forest ponds and beaver flows. This is the wood frog, the first of the New York amphibians to make an appearance each year.
Wood frogs hibernate in the leaf litter of the forest floor, usually just a few inches below the surface. Scientists have learned that these frogs, as well as the spring peeper and gray treefrog, can tolerate partial freezing of their body tissues, a condition that is lethal to most animals. They accomplish this through two methods. The first entails the use of antifreeze compounds, including the same ethylene glycol we put in our automobiles, that circulates in their blood and lowers the freezing point. The second mechanism involves removing much of the water from their cells so it doesn't freeze inside the cells. When water freezes, it expands and the resulting ice could easily break apart cell membranes.
Wood frog in amplexus.
There are two species of common dark-spotted frogs found across New York, often side by side at pond edges. The northern leopard frog is light brown to bright green with dark round spots, each with a light border, found irregularly on its back and legs. The pickerel frog has a lighter background color and squarish spots with no light border which occur in two rows down its back. There is often a distinct flash of yellow coloration on the thighs of pickerel frogs. Both are fond of the grassy and weedy borders of ponds, and are often found quite some distance from the water. Their early spring staccato calls sound like a particularly loud snore and the two species may be distinguished by the pitch of their call.
Like most organisms, frogs are vital links between food web feeding levels because they are important food sources for many other organisms. Frogs, however, play a unique role in connecting aquatic and terrestrial food webs, due to their two lifestyles. All New York frogs start life as aquatic tadpoles, feeding on plant and animal material in water. When they metamorphose into air-breathing adults, they carry some of this aquatic energy stored in their bodies and export it onto land, where it can enter new food chains.
Checklist of Frog Species Found Within New York
Frog Call Calendar
Conant, Roger and Joseph T. Collins. 1991. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Houghton Mifflin Co., Boston, MA. 450 p.
Tyning, Thomas F. 1990. A Guide to Amphibians and Reptiles: A Stokes Nature Guide. Little, Brown and Co., Boston. 400 p.
Written by Glenn Johnson, Environmental and Forest Biology, SUNY-ESF. Illustrated by Melinda Gray Ardia and Liza Corbett.
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