Imagine my surprise and interest when I noticed a newspaper article about an anaconda population crash in Bolivia. Anaconda's are the world's heaviest snake and these impressive animals can be found swimming through the swamps of South America (not Alabama). Although just about everyone has heard of anacondas, it's not a species we know too much about. Some anacondas live in a grassy wetland habitat known as the Pantanal, and there has been some research conducted on these animals. But, other anacondas live in the deepest darkest recesses of the tropical jungle, and it's hard to get in there to study these beasts.
Snakes are secretive animals. For every individual snake you see, it's almost impossible to know if there's another one hiding nearby that you didn't see. Or perhaps there were actually two more...or a hundred. This uncertainty makes it very hard to determine whether a population of snakes is increasing, decreasing, or staying the same. Perhaps that's why I thought the bold headline, "World's biggest snake threatened by backpackers" was so intriguing.
The article makes some more bold statements about anaconda population crashes and quotes a few biologists and organizations that affirm that this crisis is occurring. Although the article makes a couple mentions about various studies on the subject, I could not actually track them down. If a biologist claims that wildlife populations are changing, they should be basing this conclusion on scientific data. These data (and associated conclusions) should appear in a scientific journal. If it hasn't appeared in a scientific journal, then we don't know that it has been reviewed and approved by other scientists. It was a red flag for me that there were apparently no scientific studies or articles that described this apparent snake population crash.
But, I was prepared to give everyone the benefit of the doubt until I read further. The take-home message of the article appears to be that, 1) hikers and other tourists in Bolivia are wearing insect repellent when they venture into the jungle, 2) this insect repellent contains dangerous chemicals, and 3) anacondas are being harmed because anacondas, like other amphibians, have soft and permeable skin that absorbs these dangerous chemicals when they seep into the water.
Say what? Anacondas aren't amphibians. They're not even close, they're reptiles. Anacondas don't have permeable skin either, they have scales just like all other reptiles. It's true that there is some concern about how amphibians respond to chemicals in their environment, but I'd be very surprised if the amount of chemicals coming off of tourists and into surrounding wetlands is large enough to affect any animal, amphibian or not. If we were talking about industrial waste or pollution, that's a different issue entirely. In addition, I am always careful not to handle a frog or salamander (actual amphibians) on the rare occasions that I have insect repellent or sunscreen on my hands because direct contact could harm them. But, I just can't get over how much insect repellent I would need to have on my hands to kill animals swimming around in a swamp, especially those as huge as anacondas. Given the glaring classification error in the article, I have a hard time accepting the entire premise, which was suspect to begin with.
D. A. Steen (2010). Snakes in the grass: secretive natural histories defy both conventional and progressive statistics. Herpetological Conservation and Biology, 5, 183-188
Thursday, December 30, 2010
Saturday, December 18, 2010
A video of something that looks like an alligator attacking an electric eel has been recently pulsing through the worldwide web like the shockwaves of…well, an electric eel. Although several sources identify the reptile as an alligator, this isn’t actually the case. There are two species of alligators in the world, the American Alligator, Alligator mississippiensis, and the Chinese Alligator, Alligator sinensis. The American Alligator is native to the southeastern United States and the Chinese Alligator is native to, you guessed it, China.
Our first clue that the giant reptile in the video isn’t an alligator is the man is speaking Portuguese. Since there are no crocodilians (the group of animals that includes both crocodiles and alligators) in Europe, we can rule out Portugal as the location. That leaves Brazil in South America and a few African nations, which speak Portuguese because of the early colonial influence of Portugal. There are crocodilians in both of these continents so we can proceed no further along this line of investigation.
There are two lines of reasoning that lead us to South America (and therefore Brazil). First, on several occasions the man mentions a jacaré, which refers to a caiman (most accurately the Yacare Caiman, Caiman yacare).
There are about six different species of caiman, and they are in the same family as alligators (Alligatoridae). Characterizing relationships among crocodilians can be confusing. There are two primary families: Alligatoridae, which includes alligators and caiman, and Crocodylidae, which includes just about everything else (except for the Gharial, in the Gavialidae family). All of these animals are in the Order Crocodilia. So, an animal (like a caiman) could be in the Alligatoridae family but not really be an alligator and an alligator could be in the Order Crocodilia but not really be a crocodile. But in any case, the confusion just relates to our system of characterizing these groups of animals and the names we’ve chosen for them.
Back to the subject at hand: caiman can only be found in Central and South America. And the second way we know where this video was filmed is that Electric Eels can only be found in South America and the only country in South America that speaks Portuguese is Brazil. So there we go.
It looks as though the Electric Eel, Electrophorus electricus, is caught on some fishing line, and it’s no surprise the fisherman in the video wasn’t rushing to release it. As advertised, these eels (which aren’t technically eels at all!) can be dangerous. They produce electricity primarily to shock and stun their prey but their unique talent is also useful for self-defense. Electric eels can produce shocks upwards of 500 volts (and one ampere), which is sufficient to kill a person.
The thrashing Electric Eel likely attracted the hungry caiman (which love to eat fish, including piranhas), and the resulting encounter appears to be fatal to both. I can’t fault the caiman for going after seafood; I fondly remember an incredible fish dinner I had on the banks of the Amazon River when I was in Manaus, Brazil, about ten years ago. We were served platter after platter of exotic aquatic creatures, and one of the courses included piranha soup (I recommend washing it down with a caipirinha or two). I don't believe Electric Eel was on the menu. But I digress.
Although the video has attracted a lot of controversy, I don’t think the fisherman meant for this to happen. Rather, it seems to be the unfortunate consequence of not knowing how to react when confronted by a couple of dangerous animals.
Posted by David Steen at 6:08 PM
Friday, December 10, 2010
All too often we are presented with portrayals of rattlesnakes that rob them of their poise and dignity. In response, I contacted my friends and colleagues and requested they provide stories and pictures that more accurately represent the wild creatures we all appreciate. You can read about the campaign here. I'm proud to compile their stories below. Thank you to all the contributors. Do you also have a story to contribute? Please contact me as I hope to produce a second edition. Without further ado....
By Dirk Stevenson
I was enthralled when I first read about foraging rattlesnakes, how they use their tongues to pick up the fresh scent trails of rodents or rabbits, before coiling along a fallen log, or at the base of a tree, in an attempt to ambush their furry prey. Man, I thought, what I would give to observe this first-hand in the field. Years passed, and although I observed many rattlesnakes in the wild—rattlers under tin, under boards, crossing roads, rattlers peering at me from beneath their rocky crevice lairs, and rattlers basking lazily in the straw-colored grass atop sandhills—I didn’t come across any that appeared to be foraging.
A torrent of serendipity came my way a few years ago, when, in the span of only a few months, I met several foraging rattlesnakes. A large and gorgeous male timber (aka canebrake) rattlesnake was spotted in a classic vertical ambush posture, its forebody extending up the trunk of a large laurel oak.
I checked in on the snake on three consecutive days during which it essentially remained stationary, snuggled tight to the trunk as if glued; then, on the 4th day he was gone…”Aw, where’s my friend, I wondered”, feeling a bit lost without him… Then in a nearby sunspot I made out the crisp coal-black chevrons split by the orange line down the backbone. Looking closer I noticed a plump, squirrel-sized bolus ballooning from his belly. A victory, and a much-needed nourishment for the snake.
Getting Down to Business
By Matt Greene
Recently I was working in Walton County, Florida, restoring a sandhill that had been invaded by sand pines after fire had been suppressed. Although the area was covered in ideal groundcover vegetation, the trees were wrong for the habitat. My job was to cut the sand pine trees so they would eventually die, a process called girdling. As I approached a small sand pine tree I noticed a three-foot long Eastern Diamondbacked Rattlesnake coiled up below it. Although I photographed the snake, it barely twitched and gave no indication it was at all disturbed. I had to girdle the tree, and this snake was in my way, so walked away to focus on other trees and hoped the snake would move on in the meantime. When I returned later though, the snake had not moved. But, I had a job to do so I carefully girdled the sand pine and left. The snake never rattled once even though I was working within just a few feet of it for several minutes.
On the Trail Again
By Michelle Baragona
I recently had the pleasure of working with Timber Rattlesnakes (Crotalus horridus) in the hardwood forests of southern Indiana. Using radio telemetry, I tracked these snakes daily, getting the opportunity to observe the same individuals every week and learn about their behavior. By the end of my job, my coworkers and I were able to identify each snake by their unique patterns and individual habits. We lamented "Brian's" propensity to move hundreds of meters on a daily basis, making him exceptionally difficult to track across the hilly terrain. We cursed "Sully" and his affinity for the thorniest, steepest slopes in the area. We anticipated "Claire" giving birth and were excited to see her offspring wriggling around in the leaf litter. We came to know these thirty-some-odd snakes and wished them a fond farewell as they retreated into their rocky dens for the winter.
As challenging as it was to tromp across countless ridges and traverse thickets of brambles in 95 degree heat to locate a perfectly camouflaged snake completely buried in leaf litter, it was nothing compared to the difficulty in convincing the public of the ecological value of rattlesnakes. Most people in the area I worked were convinced that the Indiana Department of Natural Resources (DNR) was spending millions of dollars to airdrop rattlesnakes into their backyards (as well as reintroducing coyotes that kill their livestock and inducing the increasing rarity of the ruffed grouse). We were even told by our supervisors not to mention that we were studying rattlesnakes to curious passersby as to avoid any sort of controversy.
We did what we could when people did ask about the snakes; we also tried to debunk rumors about DNR, offered our services if they ever needed a snake removed from their property, and provided as much information and instruction as we could about safely dealing with rattlesnakes (most of which is highlighted throughout this blog). Although I am not convinced I completely changed anybody's mind, people were much more receptive to the idea of not killing rattlesnakes when they became more educated. And that's what Dave's blog is about: educating the public and trying to preserve these and other incredible animals. Rattlesnakes are truly amazing creatures, and I hope that through increased awareness they will continue to demand the awe and respect they deserve.
Watch Your Step
By Sean Sterrett
This photo is representative of a regular sighting during my stay as a wildlife research technician working in southwest Georgia. This particular Eastern Diamondback Rattlesnake (Crotalus adamanteus) was found in March 2006 in the course of radio-tracking Eastern Kingsnakes (Lampropeltis getula), which I did on a daily basis. My research partner and I walked right by the snake at least once before noticing it, but when we got too close its piercingly loud rattling attracted our attention. The forest was still smoldering from a prescribed burn several days before, so once I keyed in on the serpentine shape it was relatively easy to make out the brown and black pattern atop the blackened wiregrass understory. The snake’s rattling, which began only after it felt threatened, is a perfect example of how these snakes typically behave defensively when encountered, not aggressively.
By Matt Greene
On a hunch that there may be some snakes taking refuge around a rock outcrop I knew of, I hiked along the Ichawaynochaway Creek in Baker County, Georgia to check out the site. The rocky area received direct sunlight in the afternoon and was therefore an excellent habitat for snakes to warm up, particularly in advance of the coming winter. Boy, was I amazed to see this beauty basking. I don’t recall her making too much of a fuss as photographed her. Although she may have rattled when I brought my camera lens too close, she never moved. My photography session was less than a brief distraction for her daily basking.
By Dave Prada
As a field herper, someone that actively seeks out reptiles to observe and photograph, the cold days of Northeastern winters bring about a certain amount of cabin fever. Sure, I can still get outside and go on hikes, but snakes, which are the reptiles I am most fond of, are deep underground waiting for the warm days of spring to emerge. As the winter goes on, I even find myself having nighttime "snake dreams", where I'm finding and photographing multitudes of brightly colored serpents.
Towards the end of the last few winters, just when it seems I can't take the cold days anymore, a couple of my field herping buddies and I have been making a yearly pilgrimage to the Southeast. There, spring has already arrived, and the snakes have begun to emerge from their underground dens. On one sunny day last year, my friends and I were exploring some coastal habitat in the hopes of finding the king of the South and world’s largest rattlesnake. The Eastern Diamondback Rattlesnake.
We walked through the habitat with eyes peeled, as these snakes can be difficult to spot in the vegetation. I'm sure we walked right past a few without knowing it, as they would prefer to let you just walk on by without alerting you to their presence. Finally, after much tromping through the sand, I spotted some diamonds under the brush of a fallen tree. It was indeed a large Diamondback, probably around five feet long, coiled next to the hole where he had spent the winter. I quickly called my friends over, and we proceeded to admire and photograph the snake from a distance. The Diamondback was happy sitting in the warm sunshine and never budged or rattled as we slowly crept in closer for more photographs. After spending ten minutes or so taking photos, with no more reaction from the snake than a couple of tongue flicks, we continued on our way with wide smiles on our faces, feeling privileged to share our encounter with the beautiful, placid serpent.
By Aubrey Heupel
In January of 2008, my friends and I were on St. Vincent Island for an annual survey of the area’s amphibians and reptiles, and so far I hadn’t found much of interest. In fact, I rarely find much of interest on St. Vincent in January; the species I’m after tend to make themselves scarce during the winter months. However, this year as I was wandering around the trails near the lodge I came across this beautiful animal. I must have walked past it earlier in the day and only noticed the snake on my return trip, as it was catching some rays just off the trail. Although the snake was completely aware of my intrusion, it never rattled or even moved the entire time I was taking pictures and calling the others over to see my first St. Vincent Diamondback.
By Dirk Stevenson
The eastern diamondback rattlesnake is a “frequent commensal” of gopher tortoise burrows, commonly using the deep, cavernous burrows of this turtle for winter dens; occasionally, adult females give birth to their litters in or near tortoise burrows.
The iconic diamondback is a “light sleeper” and may be active on the surface during periods of mild winter weather, sometimes even taking prey during December-February. Another iconic giant, the eastern indigo snake (to 8 feet, 9 inches long), is also active during the winter months, with breeding taking place in protected subterranean shelters (like gopher burrows) from October-February.
While conducting surveys for snakes in southern Georgia and north Florida over the last 20 years, I have visited many thousands of gopher tortoise burrows (at hundreds of sites that possessed choice sandhill habitat) under ideal weather conditions specifically looking for eastern diamondbacks. Of the 60 rattlesnakes I have found doing so (that’s correct, only 60!), one has yet to act aggressively or strike at me (although a handful did rattle when I or my field companion/wife accidentally stepped near them).
The Eastern Diamondback on the left is an adult female, 4.5 feet long, found on a remote Canoochee River sand ridge, Georgia. Remarkably, we found her close to tortoise burrows during three different winters over a 5-year period! Note how cryptic (i.e., hard to see) she is when coiled against a backdrop of oak litter and wiregrass. When I discovered her on a mild (65 F) but humid January day, she was tightly coiled and oblivious to my presence—a regal lady with important things to do (namely, basking to warm her core body temperature). Another attached photo shows an awakening rattler just inside the entrance to a tortoise burrow on a warm December morning. His only interest in my camera was an occasional tongue-flick; at one point, to situate him for a photo I gently moved him with my snake stick; it was like sliding a scaly hockey puck across the sand…
The diamondbacks I have found basking on the surface near tortoise holes typically make a hasty retreat back into their burrow refuge when disturbed. Although a large and highly venomous species, seemingly indomitable, eastern diamondbacks up to four feet long are commonly preyed upon by large indigo snakes, which are mostly immune to the effects of rattler venom.
By Aubrey Heupel
In late March 2007, I decided to visit a Timber Rattlesnake den site I knew of in southwestern Georgia to see what was up and about. As the days warmed with the coming spring, I hoped I might see some snakes emerging from the ground to enjoy the sun’s light. It took a few unsuccessful visits that year before I noticed two beautiful adult snakes, they had ventured out just far enough from the ground to gain the benefits of the sun-warmed rocks. The snakes were extremely wary of my presence and as soon as my companions and I got too close they retreated back into the safety of their rocky underground den. We spotted another individual that retreated before we even got a good look at it. It is amazing how these usually solitary creatures will congregate in the same den site during the winter months, and regardless of how far they venture during the summer, they will usually return to the same den site every year
By Aubrey Heupel
One day in southwestern Georgia, I was headed to work when I came upon a beautiful Timber Rattlesnake stretched across the road. Although the snake was exposed and vulnerable, it never moved or rattled even as I was walking around it and taking pictures. It remained stretched out and as calm as can be until we safely moved it off the road.
On the other side of the state, on my way to Okefenokee Swamp, I was forced to come to a screeching halt for another Timber Rattlesnake coming onto the road. Unfortunately, roads pose a major threat to snakes and cause many deaths, as so many people feel the only good snake is a dead snake. I am the opposite, I brake for snakes (I even have a bumper sticker that will warn tailgaters of that) and help them on their way.
A Shared Prize
By Todd Pierson
Perhaps nothing is more rewarding than introducing a non-naturalist to the great outdoors. A few years ago, I convinced several of my best friends--none of which had any particular interest in reptiles--to travel west in search of scenic landscapes and rattlesnakes. Their enthusiasm for encountering these venomous snakes was low, to say the least, but I insisted.
A week or so into our trip, we had witnessed majestic mountainscapes, sunsets, and waterfalls, but we had not yet sought rattlesnakes. We had seen the charismatic megafauna of Yellowstone--grizzlies, moose, and elk--but no buzzworms. On a clear, sunny morning, we hiked through the arid plains of the northern part of the park.
Aside from a few antelope, the land appeared lifeless. Two of us passed an inconspicuous sage bush, enticing no response, but the third footfall was followed by a loud buzz. Ah, there it was! Inside the bush was a beautiful adult Prairie Rattlesnake (Crotalus viridis); my friends--inexperienced with venomous snakes--showed no signs of fear, but awe. These creatures, when respected and appreciated are not scary, but beautiful.
Don’t Tread on Me
By Jim Godwin
The Cahaba River National Wildlife Refuge lies along a stretch of the Cahaba River in Bibb County, Alabama, a short drive from either Birmingham or Tuscaloosa. Remnant patches of mountain longleaf pine forest can be found along the ridges overlooking the river and a key management goal is the restoration of longleaf on the refuge. But other, and more widespread, natural communties also occur on the refuge, one being mesic hardwood forest. Two years ago I was conducting a herp inventory of the refuge for the United States Fish and Wildlife Service (USFWS). During this time USFWS conducted an early spring prescribed burn, the timing of the burn was mid-March. An area that I used for camping was within mesic hardwood forest and this site had also been part of the prescribed burn.
During one of my trips in early April I set forth early in the morning to check a cover board array but what caught my eye was an adult Timber (Canebrake) Rattlesnake calming coiled on the hillside. The presentation of this beautifully colored rattlesnake was one of quiet poise. Two things immediately struck me, one being the total lack of crypsis, with the snake lying fully exposed in the recently burned forest. The light coloration of the body of the snake was in stark contrast to the blackened leaves and twigs on the forest floor. The second, and this from closer examination, was the presence of a light covering of dew on the snake. Immediately adjacent to the snake was a stump hole, I assume this was the snake’s usual refuge. But based on the presence of dew, instead of retreating for the evening into a protected environment the snake had apparently remained on the surface throughout the night; at the time it was found it appeared to be asleep. Although exposed to predation in this position at night, the snake was likely hunting, perhaps waiting for a mouse to walk along the adjacent branch.
After spending 15 minutes or so photographing the rattlesnake, I went about my business for the day. The snake never made the slightest movement. Although I returned to this same location many times afterward I never had another encounter with this rattlesnake.
Posted by David Steen at 1:02 PM