Monday, August 24, 2009

Heavy Rain + Amorous Amphibians = Toad Explosion

Tropical Storm Claudette had barely cleared the Florida panhandle when I was back in the woods to check my amphibian and reptile traps, scattered throughout the forest. Some of my buckets, designed to entrap small animals that fall within them, had filled with water due to the recent torrential rain and I set upon them to begin the laborious task of bailing them out. In the distance, I heard a cacophony of sounds I attributed to a noisy mob of crows, perhaps angry at a hawk that came too close.

One of my first captures that day was a large grayish toad streaked with lime green stripes.

As I held it in my hand and peered into its vertically oriented pupils (like a cat), I admired the spadefoot toad, Scaphiopus holbrooki, before me. It was the first I had seen in months. These unique animals spend nearly their entire life safely nestled within their deep underground burrows. There they wait, until heavy rains trigger some instinct within their small amphibian brains, and they are compelled to emerge. Although it matters not what time of year this rain occurs, not just any storm will do; however, a deluge will suffice. And Claudette had provided the perfect conditions.

Spadefoot toads are considered explosive breeders, meaning that when the time is right, they will emerge from their underground burrows en masse and find nearby depressions in the landscape that have filled with recent rainwater. In a flurry of singing, wrestling, and courtship, they will mate, lay and fertilize their eggs, and then disappear back into the uplands as quickly as they appeared, often returning to the same burrow from whence they came. Left behind are thousands of strings of their gelatinous eggs, the only indication of the breeding frenzy that had just occurred.

I glanced at the back feet of the toad in my hand and quickly noticed their namesake spades. Looking like the blade of a tiny shovel, the dark structures on their heels assists them in their burrowing, which they do butt-first.

When I placed the toad on the ground, it took a moment to collect itself and then hopped away into the underbrush. The next bucket I checked had two spadefoots within it, as did the bucket after that. When I peered into the third bucket three toads gazed back at me, waiting to be released. All of the animals had been captured on one side of the trap, indicating that they had come from the same area, but perhaps more interestingly, were all headed in the same direction. As I headed back to the truck, I again noticed the sounds in the distance and was puzzled by both their number and intensity.

Driving to the next site, my eye was caught by a large flooded area in the forest, an area that was dry before the storm. As I brought the truck to a stop and rolled down the window, I was overwhelmed by a rock concert of sounds. The realization slowly dawned on me that the noises I had heard in the distance were not from a massive flock of crows at all, but rather hundreds of spadefoot toads with one thing on their collective mind. I exited the truck and let my eyes wander along the shoreline and within the depths of the pool. Everywhere were toads singing, toads clasping each other and mating (knocking down vegetation in the process) and toads swimming through the water, perhaps females heading to investigate males with impressive calls. And the calls, what a sound to experience. So many species of frogs have beautiful and melodic songs; it’s no wonder how they are able to serenade females with their trills. Spadefoots however, are no Tom Jones. At risk of offending their amphibian sensibilities, I tend to describe spadefoot songs as the sound of dry-heaving.

“hooo ahhhh, hwaaaaa, hwaaaa, hoooahhh”

And they were everywhere. This was surely one of the awesome spectacles of nature that the southeastern United States can provide for the enthusiastic and alert naturalist. Reliably finding spadefoots requires both paying attention to weather patterns and knowing of historic breeding pools. When the conditions are right, one may be treated to quite the show, a show that reveals how subtle features of the landscape may be vital to the persistence of certain amphibian species.

Singing alongside the spadefoots were innumerable oak toads, which sound like baby chickens peeping. These toads also prefer to breed in temporary wetlands, where there are no fish to feed on them or their eggs. The sounds were overwhelming; to make myself heard to my field companion I had to yell over the din. I pledged to return to the site at night, when the bulk of toad activity is thought to occur. If the scene was tremendous at 11:00 in the morning, I couldn’t imagine what the experience would be like after the sun had set.

Although other obligations kept me from returning that night, I visited the site after dark the next day, eager to once again observe the frenzied toads. I donned my headlamp and waders and stepped into the water, hoping to get a close look at some of the amorous amphibians. A few minutes of listening revealed nearly a dozen different species of frogs calling to one another, I identified the boinging noise of barking tree frogs, the banjo call of bronze frogs, and the quick trill of gray tree frogs, among many others. There were also several cottonmouths cruising through the water, likely looking for frogs more interested in attracting females than paying attention to hungry and prowling snakes.

Conspicuously absent however, was any sign of adult spadefoots. I couldn’t believe that the hundreds of toads I had seen wrestling, mating and patrolling the water only the day before had disappeared. But they had. Adapted to sporadic heavy rainfall and quickly drying wetlands, the toads had come and gone in the blink of an eye. Most were likely already back in their underground burrows, patiently waiting until the next downpour to once again reveal themselves to the world. They left behind hundreds of thousands of spadefoot eggs, hard-pressed to hatch and develop into baby toads before their pond quickly dried. Strung along patches of vegetation throughout the pool, the eggs were the only evidence of the massive explosion of spadefoot activity that had transpired just the day before.

Toad photos are courtesy of Michelle Baragona.

Tuesday, August 11, 2009

The Cost of Poise and Dignity

“She never wounds 'till she has generously given notice, even to her enemy, and cautioned him against the danger of treading on her.” Benjamin Franklin

    Driving along the rural northwestern Florida road I travel nearly every day, I suddenly caught sight of a familiar serpentine form sprawled out along the dirt shoulder. As I brought my foot down upon the brakes to bring the truck to a stop, I steeled myself to pounce on the snake before me. My adrenaline pumped as I slammed the truck into park and noticed the characteristic gold and black patterning of an eastern diamondback rattlesnake.

    Almost instantly, I knew something was awry. The snake was motionless. Flustered, I noticed two additional snakes, another diamondback and a huge rat snake, the latter’s long, limp body draped along five feet of the sandy road. That the snakes were dead and mutilated was immediately apparent. Both rattlesnakes were missing their distinctive namesake; the rattles hacked from their body. All three had taken severe blows to their head; the larger rattlesnake’s head was missing altogether. They hadn’t been here for long.

    Puzzled, I took in the scene of carnage before me, shaking my head in wonderment. Had these three snakes just been run over and then salvaged for souvenirs? No, coming across a large, live snake was a rare occurrence, finding three large animals in the same spot was not likely at all. As my mind progressed from shock to disgust, I realized these snakes had been killed elsewhere and then brought here to complete some sort of macabre roadside display.

    Scratching my head and trying to ascertain some motive behind the bizarre find, I began loading the snakes into the bed of my truck. I figured I would try to salvage what I could from their shortened lives. I knew a researcher from Florida State University was attempting a large-scale genetic study of diamondback rattlesnakes; by comparing their genetic makeup in varying areas, he aims to determine if there are distinctive groups of these animals. The two rattlesnakes before me could represent important data; the species has become increasingly scarce over the years, making it difficult to obtain large sample sizes for research. The rat snake could be useful in my own studies, by examining its stomach contents I hope to better understand what this species eats and the role it plays in the surrounding landscape.

    The first snake had barely hit the bed of my truck when a pickup rolled to a stop beside me. From within, a tattooed and shirtless man gazed at me curiously with a smile. I knew immediately that this was the man who had killed the snakes. In a valiant attempt to disguise the distaste I felt, I asked if he knew anything about them.

    “A little bit.” He replied with a brief nervous chuckle.

“She never begins an attack, nor, when once engaged, ever surrenders: She is therefore an emblem of magnanimity and true courage.” Benjamin Franklin

    I assured him that killing these snakes was not illegal, so he wouldn’t be in trouble if he wanted to discuss it with me. Wearing my best poker face, I informed him I was simply interested in these animals and curious where they had come from.

    So began a familiar story. The rattlesnakes had apparently been wandering through his backyard and his children were saved in the nick of time by a few well-placed bullets. Nodding solemnly, I related that I could certainly understand the desire to remove rattlesnakes from a yard where pets and children played even as I silently wondered what kind of yard he might have to attract so many reptiles. I had seen only a handful of diamondbacks all year.

    “But why the rat snake? They’re harmless, a danger only to mice and rats around the house.”

    Although I received no comprehensible answer, I figured my point was made. Returning to the rattlesnakes, I noted I hoped he left animals alone when he came across them in the neighboring forest.

“This sounds simple: do we not already sing our love for and obligation to the land of the free and the home of the brave? Yes, but just what and whom do we love?...Certainly not the animals, of which we have already extirpated many of the largest and most beautiful species. A land ethic of course cannot prevent the alteration, management, and use of these 'resources', but it does affirm their right to continued existence, and, at least in spots, their continued existence in a natural state.” Aldo Leopold, in A Sand County Almanac

    Tapping against the side of my work truck and squinting under the hot Florida sun, I tried to summon an aura of authority as I stressed how important snakes were to my work and my research. He seemed to respect that. “Sure, I leave them be. I don’t see them too often anyway, I don’t see them much around my place anymore either.”

    I strained to sense any note of nostalgia. I often wonder if people will ever appreciate the unique wildlife of the southeastern United States before it’s too late to conserve it in any meaningful way. Rattlesnakes are an important component of southern culture; found primarily in North America, they are part of our identity. Would they be remembered as more than dangerous nuisances if they ever disappeared? Would they be missed around the campfire as men reminisced about the giants they had once killed? I wondered if he was aware of the irony of discussing a decline in rattlesnakes around his house as we sat and spoke above two of their recent corpses.

    I tried to lead him on, “Why do you think that might be?”

    He thought for a few moments, “Well, one year we sure got a lot of them, I killed seventeen of them, including a nine-footer in my rabbit cage.’

    Being familiar with the ubiquitous penchant for exaggerating the size of dead snakes, I ignored the mention of the world’s largest rattlesnake and instead asked, “You killed seventeen rattlesnakes in your yard in one year, and you don’t see many anymore?”

   He nodded.

    Although he was predictably following my carefully scripted opening, it wasn’t gratifying; it only meant that even here, bordering a vast protected area, adult diamondbacks were becoming increasingly scarce. And so I began, “That makes sense. These animals,” I nodded towards the two dead rattlesnakes, later confirmed as adult females of breeding age, “take years to mature. So, if you kill many of them in an area, it will take the population years to recover, and that’s only if all the killing stops. Once they’re gone, there’s nothing to take up their niche, to eat all those rodents.”
He nodded.

    I continued, “I’ll tell you what, I’ll give you my e-mail address and phone number. You can let me know if there’s a snake in your yard and I’ll come and relocate it. I’ll also send you some brochures I made that’ll give you information on how you can keep rattlesnakes away from your house in the first place”

    “Got it. If I see a snake I’ll let you know. So, you’re interested in them dead or alive then?”

    “No.” I said, shaking my head and smiling incredulously.

    “Preferably alive then?”

    “Yeah, preferably alive.”

“During an encounter with man the diamondback conducts itself with poise and dignity.” R. Mount, in The Reptiles and Amphibians of Alabama.

    The man slowly coasted away and the air was filled with the gritty sound of tires crushing sand. As I leaned against the truck and glanced down at the bodies of the dead snakes, desecrated and dumped unceremoniously by the roadside only moments before, I wondered if we could ever hope to emulate the dignity that Dr. Mount attributed to them in life.

Monday, August 10, 2009

The Road Less Traveled

As I slowly coasted the truck to a stop, I rolled down the window and gazed in amazement at what lay before me. Sprawled out on the pavement, encircled by alternating red, yellow, and black bands, was a dead coral snake; the first I had found despite sharing their habitat for five years. This highly venomous snake is as secretive as it is deadly, living nearly their entire lives underground. Recently, a coral snake was found in Coosa County, Alabama, after not being observed there for forty years. You can be assured they were there the whole time though, evading prying eyes due to their low-profile lifestyle.

It’s nearly impossible to make a successful, targeted search for coral snakes, even if you know they’re in the area, you just have to hope that one may show up while you’re out in the woods. Unless, of course, you’re the beneficiary of perhaps the most effective snake sampling technique out there: other people’s tires. In the course of finding mates, food, or more preferable temperatures, snakes are often required to cross roads, where they may be killed in high numbers. If you pay attention, you may realize that the roads on your daily commute are littered with the bodies of hapless snakes. If you don’t pay attention, you may be the reason why.

If you time your trip right and pay attention to the weather, driving along roads may be an effective way of surveying local snakes, especially if you pass by wetlands. The best conditions are thought to be at night after heavy rains, when the moon is not full. Although, not all species have the same preferences. If it’s a heavily traveled road, you can tally the dead snakes to get ideas about their abundance in the area. But your data collection need not stop there, for many specimens found dead on the road (or, DOR), I routinely collect them in re-sealable plastic bags, store them in a cooler, and later collect information such as the snake’s species, weight, length and sex. I’ve learned to politely smile and wave passing motorists by as I’m completing this unglamorous and occasionally odorous task. Although I strongly believe in the merits of environmental education, sometimes it’s just not worth it.

Many museums and universities hold vast collections of dead turtles, snakes, lizards, frogs and everything else you can imagine. Most of the snakes I collect end up in Auburn University’s vast collection. The specimens are used to help teach anatomy and species identification to students while researchers use the animals to test hypotheses about morphological variation and geographical distribution, among many other questions. These collections also represent baseline information about what animals were found in a particular place and time. This is particularly important when describing a new species or documenting an already known species in a previously unknown area.

My research interests include figuring out what snakes eat. Specifically, I’d like to know what snakes eat when they live in the same habitats as potential competitors. If two species eat the same things when they’re apart but feed on different types of prey when they’re in the same area, it suggests that interactions between them have influenced their behavior. Collecting and dissecting snakes found DOR allow me to non-invasively sample and answer these types of questions. For example, in 2007, I, and others, published a paper describing the habitat surrounding areas where timber and eastern diamondback rattlesnakes were found in southwestern Georgia. By comparing many of these locations, which were collected over several years, we found that timber rattlesnakes preferred to live in hardwood forests close to creeks and rivers. Diamondbacks, on the other hand, weren’t as picky about where they spent their time but they did like large areas. The differences in habitat use between these closely related species may reduce competition.

Paying attention to snakes found on the road allows me to answer questions I couldn’t have thoroughly addressed within the confines of a structured study. The next time you’re driving along, minding your own business, and spot a snake crawling across the road, imagine how hard it would’ve been to find if you had actually been looking for one.

In mid-July, while I was walking through the woods at 6:40 AM, I stumbled across this live coral snake. I'd like to say I was looking for them, but really I was scanning the treetops and listening for birds. If I hadn't accidentally startled the snake and lead it to rustle quietly in the underbrush, I never would've known it was there.

Wednesday, August 5, 2009

Have You Ever Been Bitten By A Snake?

Harmless Mud Snake
    Upon revealing to others that I research the biology and conservation of snakes, turtles, and similar animals, I can typically expect one of two reactions. The first of which is disgust and amazement that money could be allotted to such pursuits. Nice to meet you too. The second reaction, which is considerably more welcome, tends to be an expression of interest in and enthusiasm about wildlife, followed by amazement that money could be allotted to such pursuits.

    I’m often posed the same questions by different people about my career, so I imagine there are other individuals lurking out there curious about the same subjects. I include three of the questions I’m asked most frequently, in order of times asked. If you were to ask me a question about my work, would it relate to snake bites? I bet so.

1. Have you ever been bitten by a snake?

    If you mean today, there’s a strong chance I’ve been bitten by a snake. If you’re referring to over the course of my life, I’ll conservatively estimate I’ve been bitten over 100 times. I’ve only been bitten by harmless, non-venomous snakes so there is no cause for alarm here. This reliably segues to question two.

2. Have you ever been bitten by a venomous snake?

    No, and I don’t plan to be. Although I may have a cavalier attitude regarding non-venomous snakes, I am extremely cautious regarding the pit vipers and coral snake in our area. I only handle these animals when it’s a necessary component of my job and never when it is not. Don’t be fooled by television shows which serve to entertain as much if not more than to educate; I never handle a venomous snake with my bare hands. Capturing one of these animals entails a slow process of persuading the snake into a customized bucket using specially made snake tongs or hooks (similar to a golf club) Once the animal is inside the bucket, a screw-top lid is carefully placed on top and securely fastened. When processing the animals back in the lab, they are nudged (again with a snake hook) into a clear but sturdy plastic tube. Once half their body is within the tube, they are picked up where the tube ends, firmly grasping both the snake and the tube to eliminate the possibility the snake can break free.

Timber Rattlesnake

    I’m sorry to say, it can be boring to watch if you’re expecting an extended face-off with an ornery rattlesnake hell-bent on destroying me as I taunt it and wave my hands around. On the other hand, I’ll be around to bore you for many years as long as I stick to my tried and true techniques.

3. Does it hurt when you’re bitten by a (non-venomous) snake?

    For many smaller snakes, a bite doesn’t even break the skin. Imagine a sewing needle pressed against your skin (without penetrating it) and you’ve just imagined what it feels like to be bitten by the majority of snakes. For larger species, a bite can indeed break the skin but it’s hardly an emergency. Again, imagine the sewing needle just breaking the skin on your finger (perhaps as a home blood sugar test would). Snakes typically have backward facing teeth, so if there’s a snake on your finger I wouldn’t advise tearing it away. In addition to making your (tiny) wound worse, you risk pulling out the snake’s teeth. As much as it may pain you to imagine, I recommend placing the snake (and your attached hand) on the ground. When the snake is comfortable, it will try to escape as soon as it can.

    My vote for the most sensational looking snake bites go to the water snakes. In addition to being large animals they have a chemical in their saliva that acts as an anti-coagulant. So, water snake bites tend to bleed a lot more than other snake bites, but this is only a cosmetic issue rather than a health concern.

    I wash my hands after a snake bite if it’s convenient and I remember to do so, however this is often impossible when in the middle of a swamp. I haven’t yet experienced any health problems due to a snake bite, but they are known to produce some good stories.

Monday, August 3, 2009

Get Out Of My Face

Everyone knows what it feels like when their personal space gets invaded. When somebody gets too close to me, it makes me so uncomfortable that I’m almost compelled to step back and gain some distance from the other person. Just a precious few steps make a huge difference. Being from New York, perhaps I’m particularly sensitive. The amount of space a person needs is influenced largely by cultural factors; I have a few international friends who tend not to follow the same guidelines as I do. Often when interacting with them I’ll have to remind myself that they aren’t trying to determine what it takes to get punched out while I politely find some excuse to move behind a nearby chair or desk.

Many animals, typically mammals such as wolves, also like to keep some space between themselves and others. When this occurs, we tend to say the species is territorial. But although the term is often used casually, as in when referring to a neighborhood dog, it is anything but an abstract notion.

As with any biological concept, our ideas about territoriality have been refined over many years as result of scientific research, pontificating on conjectures, and arguments during scientific meetings. As a result of this debate, a specific set of conditions have been formulated to define when it is justified to characterize a species as territorial. First of all, an animal must have a territory that stays in the same place over time. So, a dog that strolls around randomly, snarling at anyone they come across isn’t territorial. Second, they must exhibit some sort of behavior that results in other animals of the same species avoiding the area. Most people probably think of bears fighting or bighorn sheep ramming heads in efforts to persuade each other to scram, both purely physical strategies. But there are more subtle methods of establishing one’s territory as well. In the animal world, scent may be the most important sense and it’s used often to dissuade others from coming too close. Think of the stray cats you’ve had strolling around in the middle of the night, they’re not just yowling, they’re spraying urine all over your house. It’s all in an attempt to keep other male cats from coming too close. So, the next time your house smells like cat pee, don’t get upset. At least there aren’t two cats prowling around.

Finally, the third condition is that through this behavior (physical or otherwise) their territory becomes an exclusive area. In other words, before an animal may be considered territorial, it must be shown that they have a specific space that they reside in by themselves only by keeping others from entering. An unfriendly dog that growls at any other dog isn’t territorial. A dog that keeps other dogs from entering its yard is. In the wild, a territory isn’t as clearly defined as a backyard, but still, animals including bobcats, coyotes, wolves, and bears defend spaces with borders known only to them. Many birds defend territories by singing (or hooting). Their sounds are often enough to persuade other birds from coming too close. Some fish species become territorial only during the mating season, forming a small territory around a nest site and chasing other fish away.

Many lizards are known to be especially territorial, they do push ups and display their colorful throats in an attempt to scare off other males (and attract females in the process) and, if that doesn’t work, they’ll fight. Interestingly, although snakes are closely related, none are known to be territorial.

I recently completed a radio-telemetry study of kingsnakes, Lampropeltis getula, wherein we implanted transmitters inside a dozen snakes and used an antenna to track them down and find out where they went. The original goal of the study was to determine how much space kingsnakes used and which habitats they prefer. But, sitting in front of the computer after the study was over, I noticed that when you traced an outline around all of the places we found a particular snake, they rarely overlapped with the outlines generated by other snakes. It was almost as if each outline was a piece of a jigsaw puzzle across the landscape. This was intriguing.

Scientists often lack the ability to research the fine points of territoriality. It’s hard to know what an animal is thinking when it’s fighting, or singing, or doing pushups. Are they acting territorial? Or maybe they’re just cranky. Instead, researchers typically focus on studying the space that an animal uses (often referred to as a home range) and then making inferences about territoriality. One of the most common methods used is to identify the region an animal patrols and then determine how much of that area overlaps with another animal’s home range.

Scientists have determined many mammals are territorial by demonstrating limited overlap between home ranges. But when I showed that kingsnakes also had low overlap, many found it hard to believe that these animals were territorial as well. There just weren’t other compelling lines of evidence to suggest they fulfilled the criteria I note above (even though they are known to fight and eat each other). My findings were eventually accepted for publication, but I had to stress that what I found was only consistent with territoriality and did not definitively state that kingsnakes were territorial. But, I still think my results were interesting. They either are the first to document territoriality in a snake or, on the other hand, effectively demonstrate that examining space use alone is not an accurate way of determining territoriality in any animal.