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Identification
Key to Texas Snakes Using Minimal-Cue Technique by Jerry Cates Part of the difficulty in putting together a dichotomous key to Texas snakes has to do with how intimate the key assumes you are with the snake you are examining. Most keys assume you have the snake in captivity, or that it is dead and you are able to examine its carcass without worrying if it will bite or not. Most of the time, however, neither of those situations applies. Most happen to see a snake in their yard and want to know what kind it is without getting too close. Many take fuzzy, out-of-focus, or long-distance photos of a snake they see and want to use that, alone, to get an idea of the snake's identity. Or, after someone else describes a snake they saw, they'd like to use that limited information to learn more about the kind of snake that person encountered. Contrary to what a lot of us believe, all of these methods work amazingly well, much of the time, provided we are willing to study the evidence on hand and use it diligently in what may be termed minimal-cue technique. Minimal-cue technique works on the theory that the visual, superficial features presented by a snake, even in a poor-quality photograph or in the hazy recollection of a friend, can provide enough information to allow us to identify its genus, and sometimes even its species. Some herpetologists could argue that that isn't true, because many--if not most--snake species exhibit a wide range of markings, colors, sizes, and shapes. Adult markings, colors, and sometimes even shapes, differ from juvenile ones. Those same "experts" will often argue that you cannot determine the sex of a snake by merely looking at its external features, but--in fact--most species of snake exhibit different characteristics for the male than for the female, if you know what to look for (it differs by species). Minimal-cue technique does work, but like sexing from external cues, you have to know what to home on in with your examination. Furthermore, minimal cue technique is needed. Minute anatomical features are, to be sure, essential parts of a complete identity picture, especially if you must distinguish with absolute certainty, for example, between a juvenile black-necked garter snake and an adult red-striped ribbon snake. But, what if you don't have all the minutiae at your disposal? What if all you saw was one small section of the snake's body, with the head and tail obscured from view? Is all hope lost? Aren't keys supposed to help the average guy or gal on the trail who can't--or won't--study the snake they saw up close and personal? This key, at least, is supposed to do that, because, for most of us, minimal-cue technique is an absolute must. In fact, most of us use it (or rather, misuse it) already, and the result, for the snake, is often disastrous. Not long ago, a good friend of mine pointed out a poisonous cottonmouth he saw while we were hiking along a small creek in northwest Austin. It turned out to be a blotched water snake. Should we assume that every dark-colored snake we see in or next to the water is a cottonmouth? Is every terrestrial snake with orange or copper-like markings automatically a copperhead? Is every banded snake with red, black, and yellow markings a coral snake? And are all snakes that vibrate their tails rattlesnakes? Are snakes with triangular heads always poisonous? Are all snakes that coil up and strike at you when cornered "dangerous"? The answer to each of these questions is no. With a little extra attention, using minimal-cue technique, most of us can distinguish between poisonous and non-poisonous snakes. This key is an attempt at achieving that goal. The key presented here, when used properly, can help you get some idea of a snake's identity with minimal cues. Keep in mind, though, that there are risks involved. Misidentifying a snake can result in a dangerous, life-threatening, even fatal snakebite. If, but only if, you act on the mistaken assumption that a snake you think isn't poisonous turns out to be, and you get too close or you pick it up, really bad things can happen. Where is the most serious error in this picture? Not in making a tentative identification that turned out to be wrong, but in acting on that tentative identification by placing yourself at risk based upon it. Please don't make that mistake! Though this key tries to limit those risks somewhat, it cannot eliminate them entirely. Even where the key works perfectly, you may still misunderstand something in a way that leads you to an incorrect or unwarranted conclusion. Consequently, it is imperative that you obey the following rules when using this key: 1. Never use this key, by itself, to positively identify a snake. Use another key, from a different source, to corroborate the information shown here, before reaching even a tentative conclusion. 2. Never use a tentative conclusion on the identity of a snake as justification for handling the snake or otherwise placing yourself or another at risk of a snakebite. 3. Always get another competent individual, whose reasoning powers are well known to you and others, to examine the available evidence with you. Consensus isn't a cure-all, but it beats going alone. 4. Remember that this key applies to snakes native to Texas only. It won't work with snakes in another region of the United States, or to other regions of the world. The Minimal-Cue Key To Texas Snakes This key assumes you have already made sure it is a snake, using the key "Is it a snake?" to answer that question. It also assumes you have already determined if the snake is poisonous or not, using the key "Is it poisonous?". If those assumptions are incorrect, please go to those keys first, then return to this key to delve more deeply into the identity of the snake you are investigating. Gross Anatomical Features 01. Distant observation Of Upper Body: 01a. Distinct body markings are evident........02 01b. No body markings are obvious..............03 02. Distinct Body Markings consisting of- 02a. -one or more lengthwise stripes...........04 02b. -side-to-side bands.......................05 02c. -blotches, saddles, or spots..............06 02d. -neck band only...........................07 03. No Body Markings, body is colored a- 03a. -pink or flesh-tone.......................09 03b. -green or blue............................10 03c. -black or white...........................11 03d. -all other colors.........................12 04. One or more lengthwise stripes, with a(n)- 04a. -orange, red , or green spinal stripe: The snake is a ribbon or garter snake in the genus Thamnophis, and is both non-poisonous and beneficial. 04b. -black or gray spinal stripe..............14 04c. -black body, salmon lower side "stripe"...15 05. Side-to-side bands with bands in- 05a. -distinct yellow, black, & red bands (not blotches or saddles[see note 05a, below], but true bands that stretch across the snake's body from side to side) arranged in the following order: (1) RED-YELLOW-BLACK--Texas Coral snake (Micrurus fulvius tener); poisonous and very dangerous. "Red touch yellow, kill a fellow" (2) RED-BLACK-YELLOW(OR WHITISH YELLOW)--one of four possible milk snakes (Lampropeltis triangulum spp.) found in Texas. "Red touch black, friend of Jack" These are harmless, non-poisonous, even-tempered snakes with gentle dispositions. Assigning a specimen to its correct subspecies is difficult, even for experts. NOTE 05a: The northern scarlet snake (Cemophora coccinea copei) and the Texas scarlet snake (Cemophora coccinea lineri) have spinal saddles, often with this order of coloration (sometimes yellow is replaced by gray) that may be confused with true bands. If the markings stop at the sides, do not extend beyond the sides to the belly, and are shaped more like saddles than bands, your snake is probably a scarlet snake, not a milk snake. Scarlet snakes are docile, rarely bite when provoked, and are harmless. 05b. -distinct red, black, & gray bands: (1). Gray-Banded King Snake (Lampropeltis alterna). Like many other snakes, this species exhibits a wide variety of colorations. 05c. -distinct black and gray bands............18 05d. -distinct red and gray bands..............19 05e. -distinct orange, gray, & black bands.....20 05f. -distinct cream, black, & red bands.......21 05g. -distinct orange, black, & red bands......22 05h. -distinct cream & dark gray bands.........23 05i. -indistinct narrow, dark & light bands....24 05j. -indistinct, broad, dark & light bands....25 06. Blotches, saddles, or spots: 06a. Large spinal blotches or saddles..........26 06b. Regularly spaced spots....................27 06c. Irregularly spaced spots..................28 07. Neck-band Only, body otherwise unmarked: 07a. Narrow black/yellow/black neck bands......16 07b. Wide black & yellow neck band with black head............................................17 12. Bright or dark green, unmarked body: 12a. Dark green................................29 12b. Bright green..............................30 29. Dark green body: 30. Blue, unmarked body: A. If the snake is dead: Both of the two species of green snakes found in Texas, the western smooth green snake (Liochlorophis vernalis blanchardi) and the rough green snake (Opheodrys sestivus), turn blue at death. No other snake native to Texas does this. B. If the snake is alive: The western smooth green snake (Liochlorophis vernalis blanchardi), which is rarely found in Texas and then almost always along the Texas Gulf Coast, sometimes presents with an olive-green body color, and very young specimens sometimes are bluish-gray or olive-green. The body scales are 15 mid-dorsal rows, and the anal plate is divided. 31. Dark green or dull brown body above: Adult Mexican or eastern yellow-bellied racer. These snakes are longer than green snakes and more heavy-bodied. Juvenile racers are easily distinguished from green snakes by their boldly blotched patterns. ---NOTE: THIS KEY IS UNDER CONSTRUCTION AND IS A WORK IN PROGRESS. COME BACK FROM TIME TO TIME TO VIEW ADDITIONS... THANKS. Click Here to go to: Texas Snakes ... Bugsinthenews |
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