The Official Houston Zoo Blog

Texas is home to more varieties of snakes that any other state in the Union.  Over 110 species and subspecies are native to Texas.  Of those, 34 varieties can be found in the greater Houston area.  What does this mean to the average person?  Well, it means that eventually, if you live in this area long enough, you are likely to encounter a snake.  Most likely, it will be a non-venomous snake.  Only six venomous species of snakes have been historically found in the Houston area; of these six, the three rattlesnake species are rarely seen and an encounter with one of them highly improbable.  Below is a brief description of each of these venomous species.

Texas Coral Snake

Texas Coral Snake (Micrurus fulvius tenere)

This is the most colorful of the local venomous snakes.  The body is completely encircled by a series of wide red and black rings separated by narrower yellow rings, while the head is completely black.  The red and yellow rings are always in contact with each other, which gives us the old rhyme “Red touch yellow, kill a fellow; red touch black, venom lack.”  This remains the best way to distinguish the Coral Snake from certain harmless species of snakes such as the Louisiana Milk Snake or the Scarlet Snake, where the red and black bands are in contact with each other.  The Coral Snake tends to be on the small and slender side, with an adult averaging under 24” in length, although the record length is 47 ¾”.

The Texas Coral Snake prefers living in partially wooded sites with a good amount of organic ground litter.  Hence, it can be found sometimes in urban areas around gardens, wooded lots, or any other places with fairly heavy vegetation or ground cover.  Its diet consists almost entirely of small lizards and other snakes.  This is the only venomous snake in the Houston area that lays eggs.

The Coral Snake is a member of the Elapid family of snakes, which includes some of the most deadly snakes in the world.  Consequently, its neurotoxic venom is much more potent than any of our other venomous species.  Fortunately, the Coral Snake is inoffensive, and bites only if provoked or handled.

 All of the other five species of venomous snakes found in the Houston area are what are known as “Pit Vipers.”  These animals all possess the following characteristics:  They have recurved, retractable hollow fangs for delivering venom, eyes with vertical, elliptically shaped eye pupils, and a heat sensing pit on each side of the head between the eye and the nostril.  Their venom is a complex mixture of enzymes which act primarily on the blood tissues.  All species give birth to live young, and do not lay eggs.

Southern Copperhead

Southern Copperhead (Agkistrodon contortrix contortrix)

 This is a light tan/pale brown snake with hourglass shaped crossbands with the narrowest point at the middle of the back.  These crossbands are of a darker color than the rest of the body.  Adults generally range between 24”-36” with a record of 52”.  This animal is the most abundant of the venomous snakes in the Houston area and is responsible for most of the venomous snake bites occurring here.  Fortunately, their venom has a low toxicity; thus, although painful, a Copperhead envenomation does not pose a serious threat to life. 

The Southern Copperhead prefers wooded areas, often in the vicinity of streams or bayous.  It can be encountered in urban parks and wooded lots, where it seeks shelter under brush, boards, rock piles, and other types of human debris. 

Newly born Copperheads measure between 8”-10” and are colored identically to the adults.  The tip of the tail, though, is a bright yellow in color.  This yellow tail gradually fades as the animal grows.

Western Cottonmouth

 Western Cottonmouth (Agkistrodon piscivorus leucostoma)

This animal is also known as the Water Moccasin.  This is a stout-bodied snake that, in general, is rather dark in color; any cross-banding pattern tends to be indistinct and rather ill-defined.  The most prominent feature about this species is its large, flat-topped head which is noticeably wider that the neck.  There also is a wide, dark-brown stripe bordered with white on each side of the head.  Newborn cottonmouths tend to be boldly patterned and, like the Southern Copperhead, have bright yellow tipped tails.  As the animal matures, the pattern darkens and the yellow tail disappears.  The Western Cottonmouth is often confused with several other species of harmless water snakes of the genus Nerodia, which, although ill-tempered and apt to bite, are not venomous.   These species, though, possess a round eye pupil and lack heat sensing pits.  In general, when confronted with a large-bodied, dark colored snake, it is best just to leave it alone.

Most Western Cottonmouths tend to be between 24”-36” in length, although the record is over five feet.  This animal can be found in almost every area that has a permanent source of water; it is especially abundant in the swamps, marshes and slow-moving bayous such as those found around Houston.  They do prefer undisturbed areas over urban areas, but can be found in wet agricultural (such as rice fields) and suburban areas.  Occasionally, the Western Cottonmouth can be found considerable distances from permanent water, usually after heavy rainfalls cause extensive flooding.

Despite its relative abundance in the Houston area, the Western Cottonmouth is responsible for few bites.  However, its venom is far more toxic than the Southern Copperhead and can cause extensive tissue damage, even though fatalities are extremely rare.  Consequently, these animals should not be molested or handled.

Western Diamondback Rattlesnake

Western Diamond-backed Rattlesnake (Crotalus atrox)

This species is the most abundant and wide spread of all the venomous snakes in Texas.  However, it prefers more sparsely vegetated and arid terrain than that found in the Houston area.  In fact, this species is not found in Harris County, although specimens have been recorded on Galveston Island and in Brazoria County.  The Western Diamond-backed Rattlesnake is the second-largest venomous snake in the United States, and has been known to reach over seven feet in length; only the Eastern Diamond-backed Rattlesnake is larger.  Average lengths, however, generally range between three and four feet. 

This large, heavy-bodied snake can be most easily recognized by its black and white banded tail (hence its other name “Coontail”).  The back is patterned with light-bordered dark diamond-shaped blotches.  The head is large and is wider than the neck. 

The Western Diamond-backed Rattlesnake can be easily provoked; when threatened, it will throw itself into a defensive posture and buzz its rattle loudly.  This species accounts for the majority of venomous snake bites in Texas; the large potential venom capacity makes a bite from this animal a very serious matter.  It is fortunate that this animal is not found around the Greater Houston area proper.

Canebrake Rattlesnake

Canebrake Rattlesnake (Crotalus horridus atricaudatus)

This is a grayish brown to pinkish brown snake with a series of dark colored, jagged, chevron-shaped cross bands along its back.  The tail is a glossy black, giving this animal the moniker of “velvet tail”.  The Canebrake is also large-bodied, and can reach over six feet in length, although between three and five feet is a more common adult length.  Its diet consists mostly of small mammals.

 This species prefers moist lowland forests near rivers and lakes such as found in southeastern Texas.  Although never abundant, this snake is seldom seen, and is now so rare in Texas that the Texas Parks and Wildlife Department has declared it to be a protected species.  

In general, this rattlesnake is relatively mild-tempered and not easily excitable.  Combined with the fact that it prefers to inhabit areas far from human habitation, bites are extremely rare.  However, envenomations from this species can be fatal.

Western Pygmy Rattlesnake

Western Pygmy Rattlesnake (Sistrurus miliarius streckeri)

This is a small, grayish-colored rattlesnake with a tiny rattle and a row of small dark spots down the middle of its back.  In addition, there are often similar rows along the sides of the body.   The harmless Hognose Snake has similar markings and is often confused with the Pygmy Rattlesnake.  Adult Pygmy Rattlesnakes are usually between 15”-20”, although the record is slightly over 25”. 

This is another uncommon snake in Texas, and is primarily restricted to wooded and open lowlands of the upper Texas coast.  Usually there is a source of standing water nearby.  Sightings of this snake, even by professional herpetologists, are rare. 

Historically, this snake has accounted for very few bites in and around Houston.  No fatalities have been recorded for this animal, even though it will bite when provoked.

What can I do to avoid snakes?

Snakes are remarkable creatures and have the same needs as any other animal.  Their three most basic needs are food, water and shelter.  Any place that provides these essential elements has a good chance of harboring one or more snakes.  Chances are that if you are encountering snakes around your house and yard regularly, you have an area somewhere that is harboring rodents.  So the first rule of thumb is to keep your house and yard well trimmed and cleaned.  Wood piles, brush piles, tall grass, trash, etc., will attract rodents and the snakes will follow their food source. Keep bushes trimmed so that their branches are off of the ground.  Seal off any gaps that may lead into the house or garage to keep snakes from accidentally finding their way into your residence. 

If you are out hiking or in the field, wear long pants and boots.  Watch where you step and don’t put your hand or foot anywhere without looking first.  Many accidental snake bites have two things in common; you don’t see the snake and the snake doesn’t see you.

If you by chance encounter a snake, our best advice is to leave it alone.  Do not try to pick it up or capture it unless you are absolutely sure it is non-venomous and are prepared to be bitten.  Snakes will not bite unless they are provoked or feel that their life is in danger.

Of course, you could always move to Ireland.

Do commercially available snake repellents work?

A picture is worth a thousand words…