Wednesday, February 24, 2010

Adirondack Amphibians: The American Toad

Every fall when I lead groups of students through the woods on a biodiversity investigation, we always have to be careful not to step on toads. It’s a challenge, for once we are off the trails, the forest floor is one big closet, full of hiding places that small animals, like toads, can use, and which we, with our clumsy feet and our eyes towering four to six feet above the ground, never see. More than once we have stumbled upon wee tiny toads and great giant monster toads. Size not withstanding, they are all one species: the American toad (Bufo americanus).

Throughout history, toads have gotten a bad rap. For some reason, reptiles and amphibians in general have been relegated to the realm of “evil” animals. European sensibilities, especially during the Middle Ages, are largely responsible for this. Fortunately, some cultures, primarily Asian, took a more enlightened view of frogs and toads. Still, what we need to remember is that concepts like “good” and “evil” are strictly human. Animals are neither good nor evil, for that implies intent. No, animals are just animals, going about their daily lives doing what they must in order to survive.

That said, the toad has some pretty nifty ways of taking care of itself. Contrary to popular belief, one cannot get warts from a toad. Sure, they are covered with warts, but these aren’t the same as the warts people get. Human warts are caused by a virus. The “warts” on a toad are actually poison and mucus glands, the former containing a milky substance that is chock full of chemicals that can irritate the mucus membranes of other animals. This is a great defensive mechanism. The two biggest poison glands are on the back of the toad right behind its head, the exact location where a predator (say a coyote) might chomp down in an attempt to grab a potential food item. The predator’s teeth puncture these glands and the animal gets a mouthful of poison. The poison will likely make the animal sick, and could potentially kill it. Hopefully the toad lives to see another day.

Here’s another defensive mechanism of the toad: bloat. Let’s say you are a toad and you are hunkered down in your daytime den – a nice cool, damp hole in the ground. A nosy predator comes along and grabs hold of your head and tries to pull you out of your home. What do you do? You gulp down a lot of air and swell up – hopefully increasing your girth enough that the predator cannot pull you out. Or maybe a snake caught you unaware from behind. There you are, your backside partway down the snake’s gullet, so you puff up, hopefully making yourself too big to swallow. This is a great strategy…unless the snake is a hognose, which has teeth in the back of its mouth that are just perfect for puncturing inflated toads, in which case there’s not much you can do.

Toads are pretty ubiquitous – you can find them just about anywhere: in the woods, in your back yard, along a stream. They aren’t too fussy about habitat as long as there is a semi-permanent body of water in which they can lay eggs, and some dense patches of vegetation for shelter and hunting. This is one reason why toads readily adapt to living in our gardens. All they need is a shady toad abode (could be an overturned pot) and they will happily patrol your garden for pesky pests like slugs.

When spring arrives, the air soon fills with toad song. The sound is often mistaken for an insect by those who are not nature savvy. It’s a trilling sort of sound, which can last sometimes 30 seconds or more. I read that you can imitate this sound if you whistle and hum at the same time. I tried it last night and I think it is safe to say I won’t be calling in any toads any time soon. Anyway, when you hear the toads trilling, it is time to stake out your neighborhood pond and see if you can see any action. Males, recognized by their smaller size and dark throats, will group together, trilling their hearts out, waiting for a receptive female to come along. When she does, the males all jockey for position, the hopefuls trying to latch on to her back and become fathers.

The female lays her eggs in double strings of sticky gel. These strands are often loosely wound around submerged aquatic vegetation. They won’t be there long, for most will hatch within a week. This is an uncertain time for toads, for life in a pond is rife with danger. The pond could dry up. Raccoons and herons are constantly looking for meals. Cannibalism lurks around every corner. What is a tadpole to do?

Fortunately, toadlets have a couple fallback positions. First, they, like their parents, have chemicals in their skin that make them less appetizing to predators. And second, they can recognize their siblings. This is pretty amazing when you consider just how many siblings they might have. A single female toad produces on average 4,000 to 12,000 eggs. Even if only a quarter of the eggs hatch, that is several hundred siblings. Knowing your siblings can save your neck, because if you hang out with your family, your back is guarded and you only have to watch out for cannibals coming at you from one side.

With all the dangers a toad faces, it’s not surprising to learn that most live only a year or two. Some robust toads might make it to ten years, and one toad lived a long life of 36 years in captivity. Even with poison glands providing protection, it’s a rough world out there. And since toads provide a great service to us by consuming pestiferous insects and slugs, I figure it’s the very least we can do to watch our steps when stomping through the woods.

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Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





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