Tuesday, August 6, 2013

Adirondack Wildlife: The American Toad

toad cropThe damp weather pattern over the Adirondacks since mid-May, while being a challenge to some creatures, has been most favorable to many others. Among those forms of wildlife that benefit from a moist atmosphere and frequent bouts of rain are the numerous terrestrial amphibians that occur in shady locations across the region.

While the Adirondacks is home to over a dozen species of these moisture-loving entities, the largest and most frequently encountered is the American Toad, a chubby and slow moving animal that is among the most recognizable members of our wildlife community.

When full grown, a toad is about 3 inches in length and has a stout or robust body that causes it to seem larger than it actually is. While a toad has the same general body form as the frog and tree frog, this brownish-gray amphibian is characterized, in part, by wart-like bumps on its back. The largest of these skin protrusions are located near its shoulders, just below its neck. These two conspicuous surface bubbles are known as parotoid glands and contain a creamy white solution of alkaloids that is quickly released over its back and sides when disturbed by an intruder.

The affect of this ill-tasting toxin causes a predator, like a fox, coyote, or bobcat to immediately spit the victim from its mouth. While in the jaws of such a carnivore, even for a brief instant, a toad may experience a fatal, crushing injury, yet the predator learns to leave toads alone, which benefits other toads in the immediate area, along with future generations of this species of terrestrial amphibian.

Regardless of how effective any defense is, some predators learn how to circumvent a protective strategy. The raccoon, for instance, has figured out that it is able to quickly grab a toad with its hand-like paws and flip it over on its back so that the secretion from the parotoid glands fails to flow over its entire body. Once the toad is on its back, the raccoon rips open the belly to expose the meaty tissues from the unprotected underside.

In response, a toad urinates on itself in an attempt to cover its body with as unpleasant a taste as possible. While this tactic may discourage some individuals from eventually eating a toad, research into the diet of several predators, like the raccoon and skunk reveal that toads are an occasional component of such forest marauders.

In the southernmost foothills of the Adirondacks, the hog-nosed snake is another animal that is not discouraged by the toxic fluid produced by a toad when attacked. This fair-sized reptile has evolved an immunity to the potent, repulsive tasting substance produced by a toad and is known to track the scent of this amphibian in order to eventually attack the chunky creature.

In addition to its chemical defenses, the toad also inflates its body cavity to appear much larger than it really is. Some smaller predators, like an ermine, may elect to pass on attacking a toad that has puffed-up its body for fear of grabbing hold of a creature that may be too big and powerful.

Like other amphibians, adult toads have poorly developed lungs which limit their intake of oxygen from the air. In order to acquire an appropriate amount of this atmospheric gas, a toad is able to absorb additional oxygen through its skin. In a setting in which the air is extremely dry, oxygen absorption through its skin is greatly reduced. This is why a toad, and other terrestrial amphibians, restricts their activity to times when the air is moist, such as after dusk when the dew point has been reached, and during overcast days when the relative humidity is near 100%. The need to prevent its skin from becoming too dry also keeps toads in shady settings where exposure to sunlight is minimal. A rocky outcropping on the forest floor with damp cracks and crevices provides numerous moist microhabitats where a toad can find shelter during those hot, dry days in summer.

This summer, sunny days with low humidity have been few, much to the delight of the toad and other terrestrial amphibians. Around my house this summer several toads have taken up residence, as I have regularly seen these creatures after dusk, as well as noting their excrement on patches of open soil during the day. The droppings left by a toad are black in color, about an inch in length and have a rounded diameter that is slightly smaller than a pencil.

Care should be used when touching a toad, as your hand could be exposed to the fluid designed to gag any larger creature. Should some of this substance be accidentally transferred to an item placed into one’s mouth, the consequences could be memorable. Please remember to wash your hands with soap as soon as possible after touching any wild creature, especially a toad, although it is best to just leave wild animals alone.

Photo: American Toad by Ellen Rathbone.

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Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

4 Responses

  1. Charlie says:

    Toads,frogs,salamanders…these are an indicator of a healthy eco-system.Whenever I see one of these kind that is what I think about and am grateful and respect and appreciate them.But then I respect and appreciate just about all living things.There’s hope for me.

  2. Dave Gibson says:

    Great post and info as always, Tom. Thank you. One of those amazing critters. One year I was putting up tennis nets at summer camp and found a toad who had overwintered deepdown in the metal sleeve that holds the net post. I took him or her out of course !

  3. Melissa says:

    What is the life span of an American Toad? What do they eat?

  4. Tom Kalinowski says:

    Hi Melissa: Most toads live for only a single year. The larger toads that you see in very late May and early June in shallow ponds are mature adults that are breeding. It is believed that in the Adirondacks, toads do not mate until they are 3 years old. These successful individuals may live to be 7 to 10 years of age before eventually dying. Toads in captivity have been known to live in excess of 20 years. Toads feed mainly on ground bugs, like crickets, grasshoppers, worms, beetles and spiders.
    Thanks for reading the Almanack and for your interest in nature.

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