Excerpts from Jim Conrad's
Naturalist Newsletter

Variable Coral Snake, MICRURUS DIASTEMA

from the August 28, 2011 Newsletter issued from Mayan Beach Garden Inn 20 kms north of Mahahual, Quintana Roo, México
At 9AM on a certain morning I was biking the white sand road along the beach when I met what's shown above.

When you see any cross-banded, red, black and yellow snake you're supposed to think "coral snake." And you know that coral snakes are deadly. But you also know that coral snakes generally are nocturnal and, more importantly, the vast majority of cross-banded, red, black and yellow snakes people come into contact with are perfectly harmless mimics of coral snakes. However, there's a little folk rhyme to help us separate the real corals from the mimics. It goes like this:

Red touches yellow,
You're a dead fellow.
Red touches black,
You're OK Jack!

In other words, if the snake's red bands are framed with narrow, yellow bands -- as in our picture -- it's a real coral. The more commonly encountered and harmless Tropical Milksnake looks just like a coral snake, except that its red bands are framed with black ones.

Actually, that rhyme works only in North America. Down here I've seen some coral mimics with red touching yellow. However, all the real corals I've seen do have their red touching yellow, so, so far, the rhyme works that way.

Our road-crossing snake was the Variable Coral Snake, MICRURUS DIASTEMA. It's very similar to the Eastern Coral Snake, Micrurus fulvius, of the US Southeast, and the "Texas Coral Snake," M. tener, which we met in Querétaro, and which is still on exhibition at http://www.backyardnature.net/q/coral.jpg.

In fact, I don't see any difference between these three species. It's just that experts say that they're different, and that what's in Querétaro is the "Texas Coral Snake" (though it's mainly a Mexican snake), and that what we have here is the Variable.

This is the first venomous snake I've seen at this location. And I was surprised to find a mostly nocturnal coral snake crossing a sun-drenched, white-sand road at 9AM. In the picture he's shining as if he's still wet, so maybe he was evacuating the mangrove swamp as it slowly continues to fill with water. He was traveling in the right direction for that.

from the March 11, 2006 Newsletter issued from Hacienda San Juan near Telchac Pueblo, Yucatán, México

Monday at dusk as I approached my lodging a two-ft-long Variable Coral Snake, MICRURUS DIASTEMA, lay upon the steps right before my door.  Now that I saw how the snake behaved I grew convinced that another snake I'd recently encountered at dusk, also on some steps nearby, also had been a coral. It had been too dark then for me to see the colors, but I clearly saw the shape, the banding and the behavior.

The behavior these two snakes shared was this: When the snake grew agitated he squirmed much more vigorously than normal for an escaping snake on a smooth surface, and every couple of seconds the snakes would suddenly launch their heads upwards and snap the air two or three times before falling back onto the ground and continuing to squirm.

Up north when I find rattlers, cottonmouths and copperheads in places where they might hurt people I put them into buckets and carry them to more isolated places. These snakes behaved far too violently and aggressively for me to fool with them, and they graciously escaped into the bushes before I could think too much about the matter.

Coral snakes are very dangerous. They're in the same snake family as cobras and mambas. Because of their small heads I've been told that corals can't bite anything larger than a finger. However, my new field guide says that they're able to gape their mouths so wide that they can bite almost any part of the human body where the skin is loose enough to be even slightly pinched so it can be held in a bite. Now when I go out jogging before sunrise my ankles tingle in anticipation...

One more note: Our Variable Coral species, different from the Central American Coral which doesn't occur here, but possibly the same as the Mayan Coral Snake found to the southeast, is truly variable. The greatest variation is in the numbers, and therefore the widths, of its colored bands. Variable Corals in northern Guatemala south of here may have as many as 50 black bands, but here in the northern Yucatan they may have as few as 12, the red bands expanding at the expense of the other bands. In fact, the snake I saw Monday basically looked like a red snake with widely spaced black bands. I didn't have the presence of mind to count his black bands but surely there were no more than 12, and my impression was that there were fewer.