What are pit vipers?

Last week I answered a question about coral snakes. The following addresses the major group of venomous snakes found in the South - pit vipers.

The Southeast has five species of pit vipers. All five - three kinds of rattlesnakes plus the copperhead and cottonmouth - are found in parts of every coastal state from Louisiana to North Carolina. Each species is distinctive in behavior, habitat, and venom capabilities, but all have one common characteristic, a heat-sensitive pit located on the side of the head between the eye and the nostril. A pit viper uses the pit in total darkness to detect the presence of warm-blooded prey such as mice or rats and to strike that prey with unerring accuracy.

The pit viper that typically bites the most Americans every year is the copperhead. That's the bad news. The good news is that copperheads have one of the mildest venoms, being determined in one study to be only 1/10th as potent drop for drop as that of the eastern diamondback rattlesnake. As far as I am aware, despite bites by copperheads to hundreds of people over the years, no one has died from the bite of a wild copperhead. Although a copperhead bite usually causes minimal damage to the victim, a trip to the hospital or doctor's office is still advisable.

Copperheads are quite abundant in some localities. However, their presence often goes unnoticed because of body coloration. Dark brown crossbands on a lighter brown background provide very effective camouflage when the snake is coiled on a ground cover of fallen leaves. At least two harmless snakes, banded watersnakes and corn snakes, are often mistaken for copperheads because of similar banding and coloration, but only copperheads have crossbands that resemble the shape of an hour-glass. Copperheads are common in the mountains and also in many coastal areas, but they can show up anywhere within their extensive geographic range in the eastern United States. Interestingly, the species is absent from all of the Florida peninsula and most of the panhandle.

The cottonmouth is the copperhead's closest relative and by far the most common venomous U.S. snake associated with water. The bite of a cottonmouth can be serious, but the snake's aggressiveness is overrated. Many bites from cottonmouths occur after someone has picked the snake up, and most of the snakebite cases I know of with these species have been to herpetologists who did just that. Hard to blame the snake for that outcome.

Of the three southeastern rattlesnakes, the smallest is the pygmy; a large one is only two feet long. The largest is the eastern diamondback, which can reach almost eight feet. The third species, called canebrake rattler in the Coastal Plain and timber rattler in the mountains and most other areas, can be more than six feet long.

What are the chances that a hiker, hunter, or other outdoor nature enthusiast will encounter and be bitten by a pit viper? And what about children? Children should be taught never to pick up any snake without supervision by a knowledgeable adult. They should learn to enjoy snakes by watching them. Of course, the same advice would apply to most adults, as many U.S. snakebites occur because someone picked up the snake. People who see a snake and then simply observe it from a safe distance (a few feet away) virtually never get bitten. And if you do encounter a snake in the Southeast, the odds are 10 to 1 that you need not be concerned. More than 50 species are harmless compared to only five that are pit vipers.

How can you identify southeastern pit vipers and what should you do if someone is bitten? The book "Snakes of the Southeast," published by the University of Georgia Press, has numerous color photographs of all southeastern snakes and is the most authoritative nature guide on the topic. Here's the advice given for snakebite victims: "The best snakebite kit is a set of car keys, a cell phone, and a companion" to get you to the hospital.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory
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What Do We Know About Coral Snakes?

Every spring I receive many questions about venomous snakes from people throughout the Southeast. Answers to some recent questions will be provided in this and next week's columns.

Q. I hear a lot about the danger of rattlesnakes and copperheads in the South but no one provides much information about coral snakes. Are they really different from the other poisonous species?

A. Snakes qualify as one of the world's most fascinating group of creatures with which virtually everyone is familiar. A snake on a playground will nearly always attract a bigger crowd than any bird, with the exception of, say, an ostrich or an albatross. People are intrigued with snakes of every size, in part because we know that some of them are potentially dangerous. Yet only six of the 52 species that occur naturally in the southern United States east of the Mississippi River are venomous. Of the remaining 46, all have teeth, and a few will bite if picked up but even these can be considered harmless.

To most people, the words "venomous" and "poisonous" are synonymous. The technical distinction is that venom is injected into the bloodstream; poison is typically injected or absorbed through mucous membranes. As far as I know, no snakes are poisonous to eat, although I have only tried a few so cannot speak with certainty about all of them. The copperhead, cottonmouth, and three kinds of southeastern rattlesnakes, all venomous, are known as pit vipers. The heat-sensitive pit is located between the nostril and eye. If you are using the presence of this pit to determine if a live snake in the woods is venomous or not, you are probably too close to the snake. The coral snake is distinguished from the pit vipers in several ways. Nonetheless, despite many people's misconception, coral snakes have hollow fangs in the front of the mouth with tubular connections to venom sacs located in the head, as do pit vipers.

Coral snakes are the only North American snakes in the cobra family. The type of venom they inject, generally referred to as neurotoxic, is distinctively different from that of most other U.S. snakes. The venom affects the nervous system and results in muscle paralysis. As the venom effect progresses through the body, the muscles of the diaphragm can become paralyzed, resulting in difficulty in breathing. If that difficulty continues, the result can be fatal.

From a human safety standpoint, southeastern coral snakes are small, rare, and unlikely to bite a person unless picked up, which no one other than a herpetologist should do. An accidental bite from an unseen coral snake is a truly rare event. The greatest likelihood of a coral snake bite is to a child who might pick up a brightly colored red, yellow, and black snake because it is pretty. The eastern variety, which is one of the 70 species of coral snakes found in the Americas, is found in the Coastal Plain from Louisiana to the Carolinas and throughout Florida.

Despite the potency of coral snake venom, a victim has plenty of time to get to a hospital. According to the book "Venomous Reptiles of the Western Hemisphere" (2004; Cornell University Press) even "the onset of symptoms usually begins during the first 2-6 hours following a bite" and "may require 48 hours to reach the maximum effect." Ample time would be available anywhere in the country to reach a medical facility.

I have firsthand knowledge of two eastern coral snake bites (to a young girl and an adult male); both of them had happy endings. Each person was bitten on the finger. Numbness and paralysis slowly progressed up the arm; the attending physician told me the man could not feel a needle stuck into his hand. When each victim was given coral snake antivenin, the process immediately reversed itself and the paralysis gradually disappeared. Why the man picked up a coral snake in the first place is a question he will now be able to answer for the rest of his life.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory
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Let's Begin America's Great Outdoors Initiative

President Obama has announced the creation of a community-based conservation plan, a program called America's Great Outdoors Initiative. The goal is to "achieve lasting conservation of the outdoor spaces that power our nation's economy, shape our culture, and build our outdoor traditions." The initiative seeks to get people, especially young people, outdoors on a more regular basis so they can appreciate the importance of the nation's lands and waters.

The much-needed reinvigoration of outdoor appreciation should include an understanding of the need for our natural environments to coexist with farming, ranching and other agricultural endeavors. We need to rekindle an appreciation in Americans, especially young ones, for hunting, fishing and other activities that put families and friends outdoors. Getting youngsters away from computers and other electronic devices for a few hours a week or month would be in society's best interest.

America's Great Outdoors Initiative gives farmers, ranchers and private landowners an opportunity to contribute by offering support for those who "help protect rural landscapes and provide access for recreation." Likewise, revenues from oil and gas removal will help protect parks, green spaces and wildlife habitats, as well as promote recreational activities at the sites. The idea is to move our country in a direction that creates "a 21st-century conservation ethic . . . for environmental stewardship" that connects us "to our historic, cultural, and natural heritage."

The president's plan is intended to develop local, community-level conservation and recreation agendas. Surveys taken across the country revealed that among the steps needed to accomplish the goals of the program were accessible parks, including "a new generation of great urban parks," or green spaces for children, and restoration of rivers to revitalize communities. The ideas presented on the Great Outdoors website at http://americasgreatoutdoors.gov/ should receive widespread support.

The site invites comments on any aspect of being outdoors and on the many issues involved with outdoor activities. Some links lead to debates among people who favor outdoor activities but do not always agree on the details, such as whether mountain bikers who pay fees should have greater access to certain trails than do hikers who pay no fees. On another topic, someone noted that "one of the things that drives me crazy as a hunter and hiker . . . is the overgrazing on Forest Service lands." Should the federal government be subsidizing cattle ranchers rather than opening up the lands for camping, hunting or bird-watching?

The first thing many will ask is how such an initiative will be paid for; how will it affect the economy? Secretary of Agriculture Tom Vilsack addressed the issue in part, saying, "America's farmlands and woodlands help fuel our economy and create jobs across the rural areas of our country. This plan seeks to work in partnership with landowners, conservation groups, states and others to conserve our working lands and our public lands and to reconnect Americans." The long-term economic value of a program that engenders new appreciation of our natural environment will more than pay for any short-term costs.

Interior Secretary Ken Salazar noted that the program was based on "practical, common-sense ideas from the American people on how our natural, cultural, and historic resources can help us be a more competitive, stronger, and healthier nation. Together, we are adapting our conservation strategies to meet the challenges of today and empowering communities to protect and preserve our working lands and natural landscapes for generations to come." Clearly, this is a long-term perspective. When we think of the environment, natural habitats and native wildlife we should always take a comprehensive, long-term view not a myopic, short-term one.

Today's children spend half as much time outside as their parents did. Also, many Americans live in urban communities without access to safe, open, green spaces. You do not have to be an ecologist or an environmentalist to know that having a society that has drifted away from its environmental roots is not good for the economy, the environment or the country itself.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory.

 

Why Don't Hawks Fight Back?

Q: A pair of red-tailed hawks has nested near our house for years. Several times I have seen one or both of them harassed by crows. I watched a five-minute dogfight today with the hawk just trying to get away. It was very entertaining, but puzzling. Why do these large raptors let the crows that are less than half their size and without their weapons harass them?

Q: I have seen crows pester a couple of big hawks. Sometimes the hawks just sit on a tree branch and let the crows fly around and make a lot of noise. Sometimes they fly away, with the crows chasing them. Would the hawks act differently if they had a nest with babies in it?

A: Very good questions about a commonly observed phenomenon called mobbing, in which several smaller birds harass a larger predatory bird. Why would a red-tailed hawk, bald eagle or great horned owl let a bunch of smaller birds, like crows, pester it? And why would a smaller bird take the risk of attacking these large predators? The answer, as is usually the case when animal behavior and ecology are involved, is complex. Some explanations seem relatively straightforward whereas others are more speculative.

From the crows' perspective, mobbing behavior may have adaptive significance in terms of survival in that a large potential predator may be driven from an area where crows raise their young because the babies might become prey for some raptors. In a situation in which a predator such as a large hawk is simply in between meals, either sitting or flying, and has no special stake in a particular location, mobbing behavior by crows could be very effective. The hawk would presumably not find the annoyance worth the effort of staying around and would move on to another area to hunt. In other words, the crows don't want the predator in the area and the hawk itself doesn't really care whether it is there or somewhere else.

In search of an answer to the question of what a pair of these birds of prey would do when harassed by crows if they had a couple of babies in a nest, I asked an ornithologist. In fact, I asked 11 ornithologists. Some are top-flight amateur bird watchers and some are professional scientists who have studied hawks or eagles. The answers I got were consistent, and surprising.

All agreed that if a red-tailed hawk reached out and grabbed a crow with its talons, that would be the end of the crow. Or as one of the professionals put it, in scientific terms, "the crow would be toast." But although large raptors have the necessary weapons, the energy cost of pursuing or otherwise attempting to catch a crow is normally not worth it. Crows are agile creatures and would be very difficult to catch in flight. So a hawk typically ignores the crows or flies away.

The answers from the bird researchers about what hawks or eagles would do if eggs or babies were in the nest were especially interesting. Statements like the following were telling. "I have never seen crows approach when young were present, but birds of prey will fiercely protect their nests." One commented, "None of our staff has ever seen crows or raccoons be predators on an eagle nest with eggs or young in it." Another said, "I don't know for sure, but when there's a nest involved, the stakes are higher and the raptor would probably fight back. The crows know this and keep their distance." Or as another put it, "When baby hawks are in the nest, the area around it becomes a no-fly zone for crows."

Observations of how hawks respond when crows use their mobbing behavior tactics are frequent. But what a pair of hawks or eagles would do if crows tried their antics when eggs or babies are in the nest remains unanswered. Ironically, the fact that such attacks seldom or never occur, may be because crows already know the answer.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory.

 

Darwin Realized That Animals Are Deceitful

If you have ever played poker, encouraged a child to believe in Santa Claus, or skirted the truth to avoid embarrassing a friend, you have been deceitful. Although humans are generally discouraged from lying, all of us occasionally tell little white lies. You may be surprised to know that the natural world is also full of deceitful behavior.

In his 1871 book "The Descent of Man," Charles Darwin noted the "marvellously deceptive appearance, through variation and natural selection" of certain tropical butterflies. He was referring to edible species with color patterns similar to those of species unpalatable to birds. The mimics resembled the inedible species "so closely in every stripe and shade of colour that they could not be distinguished except by an experienced entomologist." Darwin's innate understanding of biology was amazing.

The discovery of mimicry in butterflies is credited to Henry Bates, another famous English naturalist. Today biologists refer to Batesian mimicry, in which a harmless form has evolved to be mistaken for a noxious one to avoid predation. Early naturalists knew that animals use deceit and subterfuge to survive. Darwin noted that some animals mimic others "in order to be mistaken for the protected kinds and thus to escape being devoured." In short, many animals are unmitigated liars.

The use of color patterns to deceive potential predators is widespread. Ocelli, or false eyes, are a common deceptive feature. Many defenseless butterflies and moths have ocelli on their wings that look like a pair of large eyes belonging to a much larger creature. The ocelli deter certain predators from trying to eat the butterfly. A dramatic example is the peacock butterfly of Europe. Birds avoid attacking the seemingly big-eyed flying creature.

In the natural world, camouflage is the quintessential deceit. Some animals add a form of misdirection called flash colors. For example, the bright yellow on the back legs of the eastern gray treefrog is hidden when the treefrog is sitting on a tree. It is so well camouflaged on a gray-barked oak tree, it is virtually invisible. But when the treefrog jumps, a pursuing bird sees a brilliant flash of yellow. Upon landing, the treefrog folds up its legs and once again blends in with the tree trunk. The bird, meanwhile, searches futilely for a yellow frog.

Animals use other ways to deceive predators, including behaviors that make them appear bigger or more dangerous than they really are. Common hognose snakes carry deception to an extreme, starting with an impressive threat display. When confronted by a predator, the hognose raises the front part of its body, expands its neck and hisses. This would be an honest display if these snakes had hollow fangs and injected venom. But hognose snakes do not even bite, let alone carry any of the weaponry of a cobra or a rattlesnake, which use threat displays honestly. Then, as if it had not already been dishonest enough, if a hognose is pestered further and continues to feel threatened, it will roll over on its back, let its tongue hang limply out of its mouth and play dead. Another deceitful performance. North America's only marsupial has long held the franchise on "playing possum," but many other animals also play dead.

Though plants do not engage in Batesian mimicry, they are not above duplicity. The flower of the voodoo lily of Southeast Asia produces a smell like rotting meat that attracts scarab beetles, which feed on carrion. The flower is like a good-smelling restaurant (to a scavenger). But the restaurant is not open for business. Instead the voodoo lily hoaxes beetles into pollinating its flowers. The bee orchids of Europe engage in a phenomenon known as sexual deception. The flowers look and smell like females of certain species of bees so that males are attracted to them, which results in pollination of the orchid flowers.

Deceit is a common means of survival and reproduction in the natural world and is probably more prevalent among humans than we like to admit.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory.

What Should We Do About Rabies?

I've received the following questions about rabies.

Q. We watched a raccoon climb a tree in our backyard one afternoon. We approached and it just sat there, seemingly unafraid, on a limb five feet above the ground. It started drooling and growling, so we backed away. Later that week we found a dead raccoon in the backyard. Could the animal have had rabies?

A. It very likely did have rabies, and leaving it alone was certainly the right thing to do. Several aspects of its behavior are telling. First, it was out in the middle of the day: Raccoons are usually nocturnal. Second, it let you get close. Third, it was drooling, not something we want to see in a raccoon, one of the most prevalent reservoirs for rabies. It probably died because it was infected with the rabies virus.

According to information received later from the same county, animal control picked up two more strange-acting raccoons that were found to have rabies. Incidental cases of rabies among wild mammals are not that unusual in many parts of the country and are certainly no cause for alarm. Knowing about the disease can help people avoid problems for themselves and for domestic dogs and cats, all of which are susceptible to infection by the rabies virus.

Q. What animals transmit rabies?

A. Any warm-blooded animal can harbor the virus. According to the Centers for Disease Control the most common US wildlife species to be infected are foxes, skunks, raccoons and bats. Unvaccinated domestic pets are also susceptible, as are coyotes, which have become more prevalent in the Southeast in the past two decades. The CDC notes that small mammals, including "squirrels, rats, mice, hamsters, guinea pigs, gerbils, chipmunks, rabbits, and hares are almost never found to be infected with rabies." They are not known to have caused rabies in humans in the United States. One odd statistic is that the woodchuck (aka, groundhog), has a high incidence of the disease. According to some scientists, possums supposedly do not get rabies, although they will certainly bite if given an opportunity.

The rabies virus is usually introduced by saliva during biting; rarely, it can enter the body through mucous membranes. The virus multiplies in the nervous system, and symptoms usually develop within three months, but occasionally can appear in only a few days. Rabies victims have difficulty swallowing water, because of paralysis of the throat muscles. The seeming aversion to water led to the name "hydrophobia," which means fear of water. The loss of muscular control of the throat muscles can also result in excessive drooling, leading to the "foaming at the mouth" symptom.

The first line of safety precautions for dealing with rabies is pretty much common sense. Don't pick up a drooling, growling raccoon (in fact, don't pick up any wild raccoon). Likewise for sick or injured bats. Bats are beautiful animals in flight, especially when they are eating mosquitoes, but if you find one on the ground or in a house, don't let it bite you. CDC records indicate that rabies has been documented in bats from all 48 of the conterminous states. All domestic dogs and cats should be vaccinated, especially those likely to go outside or come in contact with wild animals.

Q. I have heard some people suggest that we should start vaccinating wild animals to prevent rabies epidemics. Is this feasible?

A. Such a plan would be costly - and it's unnecessary. Wild animals are not the problem if we avoid situations in which we are likely to get bitten. CDC records show that "control of dog rabies through programs of animal vaccination . . . reduces the incidence of human rabies." Rabid dogs are the cause of more than 90% of human infections of the rabies virus and the source of more than 99% of human deaths from rabies worldwide.

We should have our pets vaccinated at a vet's or a rabies clinic, but let's leave the wild animals to take care of themselves.

Send environmental questions to ecoviews@gmail.com.

Whit Gibbons is an ecologist and environmental educator with the University of Georgia's Savannah River Ecology Laboratory.