If possible, actual dimensions should be gathered. Many pit vipers have triangular heads, but other snakes can resemble the same shape when they deliberately flatten their heads in aggression or anxiety. Knowing if the snake has a round, long, or oval head will help in identification but is not any proof of venom or lack thereof. Eye color, pupil shape, location on the face, and eye size should all be noted.
These three identifiers: body length and width, head shape, and eye characteristics will narrow down the possibilities for species identification. Color is usually very helpful in determining the type of snake you have located.
Many snakes have distinctive patterns. Noting the patterns and the colors is very important. Sometimes the difference between a harmless snake and a deadly viper is one ring of coloration. Blotches usually refer to patterns with no symmetry. Theses markings are often rectangular with darker edges. If a diamond pattern is noted, color and color pattern should be noted as well. Are there speckles flecks of color or spots large or small defined, solid color circles? Ring patterns appear like bands around the width of the snake.
Stripes are patterns lengthwise down the body. Note color contrasts. Some snakes are one color on the dorsal side and a different color on the belly. Distinctive markings on the head and neck may be present. Lastly, some snakes have no markings at all and are one, solid color. Tail characteristics are another guide to identifying a snake. Tails can end with a rattle. They can be pointed or rounded. Some have specific patterns. When the snake is turned over, is the scale near the anus single or divided?
Experts are able to use the number and arrangement of scales on a snake to further assist in the identification process. Once all the information is gathered, a field guide will help you narrow down your list. The characteristics noted will pinpoint one or maybe a few species suspected. Some snakes are almost identical, and it is these snakes that need the assistance of habitat evaluation.
Some of the best titles for Texas are listed at the end of this document. The more species of snakes you observe and identify, the more you will come to appreciate the beauty and complexity of coloration and pattern design. For many herpetologists people who study reptiles , snakes embody incomparable works of art. Many snakes give their identity away by their characteristic and sometimes bizarre behavior.
An excellent example of this is that of the super thespian, the Texas hognose snake, who can really put on a show. This amazing critter has evolved an elaborate pattern of behavior designed to make it as unappealing as possible to any potential predator. If molested, according to Alan Tennant, it may coil or raise its head, and flatten its forebody to make you think it's bigger than it really is. If you are still unimpressed, the snake will next launch several pseudo strikes in your direction, violently jerking its head backward each time.
This should immediately suggest to you the aggressive style of pit vipers and frighten you off. If not, next the intrepid snake will emit a sharp, hair-raising hiss with each breath it takes. If the observer continues to be unmoved by all this, the snake will proceed to act two of the performance.
It now resolutely conceals its head under its tightly spiraled tail and begins to writhe convulsively, regurgitating and at the same time discharging a foul-smelling musk form its anal glands. Still not convinced? The final ploy - the piece de theatre so to speak - the snake turns belly up with its tongue hanging loosely and pathetically from its open jaw - to all appearances dead as a door nail. Should you take a stick and try to turn it upright - bingo it will flop back over again. Just to let you know in no uncertain terms, there is no such thing as a dead snake in an upright position.
In evolutionary terms, this amazing repertoire of behavior must have worked more times than not, or these snakes wouldn't still be around doing this. Not all snakes exhibit such amazing antics, but many of them do have characteristic behaviors that will give you immediate clues to their proper identity. Generally snakes are shy and retiring. And when you think about it, they really live rather sedentary lives. Most are non-migratory and if they do migrate, they don't go long distances.
Much of their behavior is a function of survival within the limits and opportunities of ectothermy or "cold-bloodedness. Like all living reptiles, snakes are cold-blooded or, more appropriately, ectothermic. This does not mean that their blood is always cold, but that their body temperature varies with that of the external environment. Unlike war-blooded birds and mammals, snakes are unable to regulate the temperature of the body internally.
Snakes can, however, absorb heat form the ground, form the surrounding air, and from objects next to them. They can also create certain amounts of heat by flexing their muscles. This makes their life style different, but not necessarily inferior to that of birds and mammals.
In fact, snakes have been able to colonize and adapt to many environments which have proved hostile to warm-blooded animals. Being ectothermic demands less energy. High levels of metabolism don't need to be maintained. So snakes aren't forced to eat all the time. Growth does not have to be constant, rather it can be discontinuous with long pauses between spurts. There can be long periods of fast between meal-times, sometimes as long as three years.
Cold-bloodedness is the original or ancestral state of life all invertebrates, fish, amphibians and reptiles are ectothermic , it is not an inferior state, just different, with different limitations and possibilities. Being ectothermic makes snakes sensitive to both very cold and very hot temperatures. They have a narrower range of temperatures, only about 30 degrees, within which they can survive. Snakes need to hibernate when the ground freezes and air temperatures descend below 32 degrees for extended periods of time.
Likewise, they need to take shelter during times of excessive heat. Temperatures over degrees for prolonged periods can be lethal. Snakes protect themselves from temperature extremes by means of behavioral modifications rather than by internal thermoregulatory devices.
To warm itself, a snake can bask in the sun, or lie on a paved road at night. To protect itself from cold temperatures, it can burrow deep below the ground where the soils are warmer and unfrozen.
Snakes are absolutely dependent on external heating for their muscular activity and the important life processes of digestion and gestation. They cannot derive their body heat chemically from their own metabolism. So they can live only in parts of the world where the daily and seasonal temperatures are fairly equable. Snakes are just as sensitive to overly hot weather as they are to excessively cold temperatures.
Survival time under extreme conditions can be as short as ten to twelve minutes. Even sidewinder rattlesnakes may succumb to the heat at about degrees depending on the duration of exposure.
Under cold temperatures, a snake becomes increasingly lethargic. Instinctively it will seek some refuge. It must do this before it becomes immobilized by the cold.
In paralyzing cold, snakes can no longer procure food or defend themselves against enemies. In short they can no longer move. The can endure temperatures of 37 degrees for a few days, but not extremes in the teens. Temperatures between 80 and 90 degrees are probably the best and most comfortable for them.
Snakes will behaviorally adapt to the temperature ranges of an area. In habitats where daytime temperatures are lethally hot, they will confine their activities to the night. In an area with excessively cold winter temperatures, a sudden drop in temperature will induce long periods of wintertime hibernation with activities resumed in the spring with the return of warm temperatures. Many snakes mate and resume foraging activities in the spring. Snakes can cool themselves by seeking shade, lying in shallow pools of water or crawling down a rock crevice out of the sun.
They can warm themselves at night in hot climates by lying on still warm paved highways. Snakes are essentially solitary and don't congregate into large organized groups. Certain favorable environmental conditions such as the burrows of other animals, attractive shelters for hibernation, or termite galleries may attract small groups of individuals. There is, however, no community like or social structure within these groups.
This lack of social organization may make it difficult for snakes to find members of the opposite sex during mating season. Males search out females by smell. Females may, however, congregate at egg-laying areas that are especially suitable. Snakes are comparatively long-lived. Even small snakes may live as long as 12 years. Large species may live to a ripe old age of 40 years or even longer.
There are no snake vegetarians. Snakes are confirmed meat-eaters. Eggs are also a favorite menu item for some species. Prey is generally swallowed whole. It is usually take alive. Thorn-like teeth which are curved backward help move the prey item in the direction of the stomach.
The prey is often seized in the mouth by a rapid strike, and the process of overpowering and swallowing begins.
If the snake is nonvenomous, the prey is usually small in size relative to the snake. A few species can subdue larger more active prey by constriction, thus immobilizing the victim before swallowing it.
Poisonous snakes are able to subdue large active prey items by striking them, envenomating them with a complex proteinaceous substance which both begins the digestion process and kills the victim at the same time. Many venomous snakes will immediately release their prey, allowing time for the poison to do its work, and locate them later by means of the heat-sensing pits, sight or scent.
Once relocated, they proceed to swallow the moribund carcass. Teeth are frequently broken off in the process of the strike, but they are soon replaced with new ones ready for use.
Most snakes have restricted food preferences, while others are more eclectic in their tastes and will take anything that they can effectively subdue and engulf. A number of snakes specialize in taking certain kinds of prey only and have special adaptations to do this. Slender blindsnakes specialize in eating ants and termites. Hognose snakes are toad specialists.
The crayfish snake, as its name implies, targets crayfish or similar crustaceans. Some snakes are fish-eaters, others are bird egg specialists. Kingsnakes and Indigo snakes are snake specialists, Smooth and Rough green snakes are insect-eaters with a special liking for crickets, grasshoppers and caterpillars.
Rat snakes, great friends of the farmer, of course, love to eat mice, voles, cotton rats and the like. In temperate climates, mating usually takes place in the spring. Commonly a snake will have spent the winter in the company of others of its kind in a large hibernation burrow.
Snakes emerge en masse from their dens at this time and can be found basking in the sun, sometimes in significant numbers. The first order of business, aside from eating, is for the snakes to shed their skin. This molting activity releases a chemical signal in those female snakes that already have mature eggs in their oviducts triggering a readiness to mate.
Males probably locate females by scent which arises from epidermal secretions emanating from just inside the female's cloaca. Certain female snakes mate with only one partner in a season while other females store viable sperm from several males for various lengths of time, sometimes up to five years. Courtship usually consists of pushing, rubbing and weaving movements initiated by the male. He will rub his chin against the female's neck thereby stimulating her to receptivity.
In some cases there may be a nuptial interlude where the snakes coil around each other. Males of some species participate in what is described as a ritual display of aggression called a combat dance. It is not known whether this is territorial or a display to females in the vicinity. It is only done during mating season and it occurs only between males. Fertilization is internal and the male will terminate courtship activities by getting into position with relation to the female and inserting one side of the double pronged intromittent organ called a hemepene.
Sperm passes along a groove in the hemipenis and enters the cloaca then travels up the oviduct where it fertilizes the waiting eggs. Females of some species appear to guard their eggs, but this is not commonly observed in most species. Young rarely if ever receive any kind of protective care form the female. Most snakes simply lay their eggs on the ground usually in warm damp soil. May lay eggs in or under rotting logs, under bark of downed trees, under stones, in holes in the ground or other secluded spots.
Snakes can lay as few as 1 to as many as eggs. A number of snake species bear live young. Few snakes exhibit any kind of parental care. Snakes and people have the same arch-enemy: people. Humans have always waged war on snakes and there is no way of knowing just how many millions of harmless individuals have been battered, shoveled, run over, gassed, and shot to death through the years.
And while it's understandable that people object to the dangerously venomous snakes, it is a shame to kill all the harmless ones too, giving as a rule of thumb - the only good snake is a dead snake.
For many of us, any enemy of a snake is a friend of ours, no matter what form it may take. In the natural environment, several animals stand out as enemies of snakes.
Badgers are major snake predators so are weasels. Several species of wild cats including mountain lions, bobcats, ocelots and jaguarundis will take snakes. The domestic and feral cat should be included in this group. Domestic cats will often take the smaller snakes, both harmless and venomous.
Other snakes and large lizards are known to prey on snakes. The indigo snake and the kingsnake are well-known snake predators. Kingsnakes appear to be highly resistant to the venom of most venomous species and over power their victims by constriction.
As a matter of fact, a kingsnake will eat almost any snake they find that is small enough to be eaten whether it is venomous or not. When you think of it, the elongate body of a snake is a very convenient shape for consumption by another snake - no pesky legs or horns to get in the way. Some people in South Texas and Mexico used to keep indigo snakes as pets around the house to keep other snakes away.
Some birds are well known snake predators. They may eat them as part of a diet which includes other groups of animals or they may be specialists. In the United States, perhaps the best known avian snake predator is the Greater roadrunner.
They probably eat more lizard than snakes but that has not prevented quite an elaborate folklore to grow up about their snake hunting prowess. Some roadrunners were reputed to build a wall of cactus spines around the rattlesnake victim so that it would die of heat prostration. Smart bird, probably fiction. Laughing falcons in Mexico are snake specialists and focus most of their foraging attention on the capture of snakes.
Turkeys, many large buteo hawks, eagles, herons and cranes are also known to devour snakes with relish when they are small enough to capture. As for domestic animals, pigs like to eat snakes and will attack them viciously before devouring them. They also appear to have a high resistance to snakes venom due to the slow transfer through all that fat. But finally all of the above are no match for man.
Through direct actions or indirectly we have completely eradicated snakes in some localities. We have destroyed or modified their habitat and their food supply. We have wiped out great numbers of individuals due to fear, anger, sadism, greed, fun, desire for their hides, or to a lesser extent, for food. Of course, snakes are not our only victims, other animals suffer too.
But because of widespread human aversion, snakes have been singled out and targeted as bad animals and have been persecuted beyond all reason. Think about it, suppose you had neither arms nor legs and were shaped like a flexible hose, with top speeds not exceeding 3 mph. Add to that, being cold blooded and always at the mercy of the weather, especially the temperature, how would you defend yourself?
Amazingly snakes have evolved a number of ingenious behaviors and clever strategies to stay alive in an often hostile environment filled with hungry, aggressive, warm-blooded predators with highly developed senses.
Snakes are like magicians, and many of them sport a versatile bag of tricks. Most snakes have adopted a somewhat cowardly or cautious attitude towards danger. Defensive tactics include staying hidden and relying on their excellent camouflage in hopes that the predator won't notice that they are even there. I suspect that this is one of their most successful ploys.
Some snakes will curl up into a tight ball with their vulnerable head tucked safely and inconspicuously away somewhere in the middle of their body.
Other snakes will play dead or try to "bluff" the potential predator into thinking they are larger and more dangerous than they really are. A very common and consistently resorted to strategy is to leave the scene of danger as quickly and unobtrusively as possible, avoiding confrontation at all costs.
Discretion is the better part of valor. Finally a few snakes have evolved the ability and the arsenal of equipment necessary to stand their ground and defend themselves against enemies much larger than themselves.
If cornered and not given an opportunity for retreat, they will strike with speed and force and envenomate their enemy. An animal that has venom is called "venomous. So although some people refer to those snakes as "poisonous," technically, they mean venomous.
Unfortunately, there is no one simple hard and fast criterion a person can use to tell a venomous snake from a harmless one. None of the popular criteria such as a broad, triangular head, a heavy body, cat's eyes vertical pupils , a flat body, or rough scales are safe since both harmless and dangerous snakes are known to share some or all of these traits.
The only unfailing method is an examination of the snake hollow of grooved fangs and venom glands. For obvious reasons, this is not a practical approach.
A better method is to know which venomous snakes occur in your area and have a good idea about what they look like. With this in mind, keep a copy of a good field guide to Texas snakes handy, and remember a few simple facts.
While many species of harmless snakes will vibrate their tail, only rattlesnakes have rattles which produce a recognizable "cicada-like" buzz. And while most rattlers will sound their rattles when they sense your presence, this is not always the case. If you catch a rattlesnakes totally by surprise, ti may choose to strike first. Pit vipers, such as rattlesnakes, water moccasins, massasaugas, and copperheads, do have cat's eyes with vertical pupils, but so do Texas lyre snakes, Northern cat-eyed snakes and Black-lined snakes which are harmless.
Knowing the range of these latter snakes and knowing where you are will make this a more valuable criterion. The Texas lyre snake occurs only in extreme West Texas while the Texas cat-eyed snake and the Black-lined snake occur in extreme South Texas. Coral snakes, which are venomous, do not have cat-eye's. They are the only venomous snake in Texas that is brightly colored red, yellow, and black bands completely encircling the body.
Because harmless Texas scarlet snakes and Louisiana and Mexican milk snakes share the red, black, yellow coloration pattern, it is important to notice the order of the colored bands. A good memory-jogging device to learn is "Red next to black is O. Many large harmless snakes appear to have large triangular heads which are wide in proportion to the neck, especially when you are looking down at them, so this is really not a good criterion in the field.
Additionally, many harmless snakes can make themselves look and act like pit vipers, the Texas hognose snake is a good example. Water moccasins, also known as cottonmouths, do not have rattles, but the do have facial pits. Sometimes these are hard to see without binoculars and still maintain a safe distance. Blotched, Yellowbelly and Diamondback water snakes are often mistaken for water moccasins because they share thick trunks, dark, dimly patterned backs and sides, as well as the same aquatic habitat.
Cottonmouths do exhibit rather distinctive behavior, however, that usually helps to differentiate them in the field. They are significantly less agile than water snakes and often hold their ground and gape open-mouthed in a threat posture. The open gape is cottony white, hence their common name. Copperheads are venomous and can be prevalent in wooded suburban neighborhoods.
While their venom is only about half as destructive as that of an equal quantity of western diamondback venom, they are sometimes hard to see in habitat. Due to their cryptic coloration, they blend in beautifully with their surroundings.
While they are not highly aggressive, they often get stepped on. According to Alan Tennant in Texas Snakes , not a single death resulted from copperhead bites over a year period. The best defense against venomous snakes is avoidance. To avoid a particular animal, it is best to know what it looks like and where it is likely to be found. Snakes are often found under rocks, fallen limbs and in the leaf litter.
Rodents are one of a snakes favorite meals, so avoid areas where mice and rats may be, such as trash, brush and rock piles, stacked lumber and stone walls fences. When outdoors, always look where you step. When you know you are going to be in snake territory, wear boots, thick jeans or chaps and gloves. Never reach under rocks or into holes or other blind crevices. This is definitely asking for trouble. If your are playing ball or frisbee and it lands far from you in tall grass, LOOK before you reach down to pick it up.
This also goes for hunters who are retrieving their downed game. Look before you reach. Don't remove or turn over stones and rocks with your bare hands. Be careful when climbing around rocks and watch where you sit. Always watch where you step on warm rocks, especially in spring. Basking on rocks is a popular activity among snakes as they warm themselves in the cool morning air.
Be careful when stepping over or on fallen logs. Always pay attention to where you step and make sure you can see where you are placing your feet. The best rule of thumb is to watch where you put your hands and feet; don't put them in places without looking and don't put them in places where you can't see.
If you lift a stone or log or any object under which a venomous snake might be, first move it with a stick or hook. Don't place your fingers under it. You can use your foot if you have thick leather boots. If you are walking in grass brush or cactus patches, stay in the cleared areas as much as possible.
Remember rattlers are hard to see in their natural habitat as they are protectively colored. Avoid walking around your campsite in the darkness. Rattlers are nocturnal much of the year.
0コメント