Sunday, August 7, 2011

Things that go Jump in the Night: American Toad (Bufo Americanus or Anaxyrus americanus)

American Toad, Bufo americanus
Photo by Brad Sylvester, copyright 2011, all rights reserved
Fortunately, not everything that lives in my yard is hard to identify. This creature, for example, is an American toad (Bufo americanus). I don't need to spend time looking up any identification options, or tracing the taxonomy tree for this fellow.

There are only two types of toads in New Hampshire: the American Toad and Fowler's Toad (Bufo fowleri). From this view, they are fairly easy to tell apart. The largest black spots on the back of the Fowler's Toad would contain 3 warts each. The American Toad as you can see easily in this photo, has one or at most two warts contained in each of the large black spots on its back.

The American toad also has noticeably larger warts on its tibia (between the knee and the ankle) than on the rest of its leg, another trait clearly visible here. If you were to look on the underside, you'd find dark spots on the belly of the American Toad which would be absent on a Fowler's Toad.

The only complicating factor is that occasionally the American Toad and the Fowler's Toad will mate with each other resulting in a hybrid of intermediate features. That is definitely not the case here. The Fowler's toad tends to live along the major rivers of New Hampshire (The Connecticut River and the Merrimack River), so it would be unusual to find one in my yard, anyway.

American Toad (Anaxyrus americanus or Bufo americanus)
Notice the dark spots on the  underbelly.
Photo by Brad Sylvester, copyright 2011, all rights reserved
Do Toads Cause Warts?

OK, most you you are waiting for me to address the issue of warts. As a kid growing up in New England, it was common knowledge that handling a toad could cause you to get warts, especially if the toad decided to wet your hand as you held it. I say it was common knowledge because every kid knew it. It is completely false however. Warts are caused by a virus that is not zoonotic (passed between animals and humans). If you don't believe me, Kids Health backs it up. There is absolutely zero chance of catching warts by handling a toad.

Don't Lick a Toad!

American toads do, however, have a poison gland above the eye. This poison is designed to deter some predators. While this poison is generally not harmful through normal skin contact, care should be taken not to get it in your eyes (such as by rubbing your eyes after handling a toad) or to swallow it (I don't know, by licking a toad, I guess...).

A Common New England Night Caller

In most parts of New England, the American Toad is one of the most misidentified night callers. People with no experience or training often mistake its call for peeper frogs even though the two have very different voices and calls. If you are often out after dark in New England (outside of a city environment) you have probably heard the call of the American Toad. It is a long trilling sound. You can find a link to the audio of the American Toad call about halfway down the page here at Nature North who also informs me that the Genus Bufo has been officially changed to Anaxyrus, so instead of Bufo americanus, American Toads are now Anaxyrus americanus and Fowler's Toads are now Anaxyrus fowleri, but what's in a name. That which you call Anaxyrus is still covered in warts...

American toads don't have a specific habitat. They live pretty much everywhere in the eastern United States and Canada. They can be found in forests, river valleys, on mowed lawns, planted fields, and everywhere in between. Consequently, numbers of this  species is not in significant decline because they are not being displaced by habitat loss. If a forest is converted to suburban development, the American toad stays and continues to prosper. They are often seen in the daytime, but are actually nocturnal. If they can, they stay hidden in their burrows during the daytime.

American Toad Tadpoles:

American Toad tadpoles are small with a skinny tail and often seen in very densely populated permanent or semi-permanent pools or small ponds. Because of the small pools in which they are often found, they tend to be easy to catch and it is not uncommon for children to scoop up a few and bring them home to watch them slowly turn into toads (although most kids are expecting frogs from these little black tadpoles). They are generally OK with water conditions that would be suitable for a goldfish, and will even eat fish flakes, although natural algae and decaying vegetation is probably better for them. If decaying vegetation is put in the tank, then a charcoal filter is absolutely required.

Quick facts about Anaxyrus americanus:

Diet: Adult toads eat insects and worms of all sorts, especially beetles - like the Common Black Ground Beetle that seems to be so prevalent in the wooded area of my yard. As tadpoles, I've observed them eating algae from the sides of rocks in the shallow pools in which they hatch, it's a likely bet that they also eat decaying vegetation from the bottom of the pool. Because of the population densities I've observed, they most likely do not rely on zoo plankton which would be quickly stripped from the pool.

Life Cycle: American toads lay eggs in water in the spring which hatch in less than two weeks, sometimes considerably less. The tadpoles stay in the pools for roughly 30 days or a little longer as they become toads. They first grow tiny back legs and then front legs appear. The tail will slowly shorten and disappear until the toad is completely metamorphosed. Once that happens it will soon leave the water and begin life as a land-based toad.

Lifespan: Ohio History Central says the American toad's average lifespan is 5-10 years, but they have been known to live as long as 30 years.

When is it here? The American toad does not migrate and is here all year round.

Where do toads go in the winter? In the winter, American toads hibernate in a burrow in the ground. I didn't have any information on the depth of its burrow, but it seems very unlikely that this cold-blooded creature is getting below the freeze line which, here, can run a couple feet deep during a cold winter. That means that their tissues almost certainly contain some sort of antifreeze chemical that prevents them from freezing solid.

Species status: Prevalent, not threatened at all

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