Sunday, January 31, 2010

This ain't like the swimmin' hole back home

We were given some free time this afternoon to explore the area, with the hope we’d use the break in our schedule of presentations and paper writing to think about the independent research projects we’d be starting tomorrow. I thought this was a good opportunity to not ponder my project but to hike to the nearby Rio Tempisque. Although the marsh adjacent to the research station was chockfull of juvenile crocodiles, the adults could be found only in the deep and flowing river. So, after lunch, I filled up on water and began the roughly four mile hike to the nearest access point. I was disappointed to hear that I wasn’t likely to see any of the large animals I was after, as they’re most often seen basking along the river far from any area I would be able to reach without a boat. But, I figured it was worth a shot.

Wildlife is a professional interest of mine; I plan to make a career of researching the ecology of animal populations and assemblages. However, sometimes my interests are less formal…sometimes it’s just neat to see something cool. And crocodiles fit the bill. Reptiles are an often maligned bunch, as a group, they’re frequently ignored, disparaged, or killed. But crocodiles are the reptilian cousin you know better than to disrespect. Share their territory without taking appropriate precautions and there’s a very good chance that they will take the opportunity to kill you, drag you to the bottom of the river, and eat you. Period. That kind of power is awesome, and sometimes it’s beneficial to be reminded that humans aren’t always the top dog. We’re just a piece of the puzzle.

Shortly after I disembarked, I realized one in the afternoon was probably not the best time to take a significant hike, even if the terrain wasn’t more hazardous than a dirt road. As the tropical sun beat down on me relentlessly, I took occasional refuge in the shaded woods nearby and waited until I felt sufficiently recovered to return to the road. About an hour into the walk, I noticed a shaded concrete structure on the side of the road that looked as though it was built to control a small stream. Reduced to a single puddle now, the water likely flowed freely during the rainy season. Knowing this small amount of water was likely to attract thirsty animals, I spent some time poking around the pit while enjoying the shade.

Back on the road, the forest broke suddenly and I was quickly on a steep slope overlooking a muddy and flowing river perhaps 200 yards wide. Before I had even gathered my bearings, I noticed a dark shape in the far distance, just above the water’s surface.

It seemed to defy the current as it steadily crossed the river. Incredulously, I used the zoom on my camera to gain a better view of the distant form. Once I had taken the picture, I magnified it within my camera and could finally make out the distinctive bumpy profile of a crocodile.

It was huge, there’s no way to know with confidence how long this crocodile was, but it was clearly an impressive animal.

A boat suddenly appeared from around the bend of the river and I saw no more crocodiles for about twenty minutes as I relaxed along the bank. Not looking forward to the hike back to the research station, I was rewarded by the sight of another large crocodile (the same one?) quickly hauling itself onto a muddy bank to bask. Way too far away to make out the details of this individual, I longed for a powerful spotting scope.

I had signed myself out only until 4:00; afterwards the course instructors would start to wonder whether I had gotten lost or needed help. So, with a long hike in front of me I reluctantly stood up from my rocky seat. Immediately I noticed yet another large crocodile, this one on the opposite bank; my best look at these large animals yet. It sped down the river and out of sight like a torpedo.

On my hike back I was quickly once again upon the concrete holding pool, and what I saw within it froze me mid-stride.

Although I was in disbelief, there was no mistaking the eight foot crocodile in the shallow water. Shallow water I had casually strolled around just a little over an hour earlier.

Suddenly confronted by a large crocodile less than ten feet from me, I instinctively looked behind me and into the surrounding forest to scan for danger. When I came to my senses, I realized I was safe. Protected by the concrete walls of the pool, I slowly raised my camera and took some quick photographs. The crocodile was motionless, but when I saw its back foot shift slightly I realized I was probably pushing my luck. Fearing an impending freak out by a large cornered crocodile, I quickly made my exit.

When a large lizard rustled in the underbrush shortly thereafter, I think I left the ground.

Saturday, January 30, 2010

Act like you've been here before...

Nine years ago, almost immediately after arrival at a biological field station in northeastern Costa Rica, I noticed a small and colorful frog hopping across the path before me. My mouth dropped as I realized the black frog lined with neon green was a poison-dart frog (specifically Dendrobates auratus). Growing up in the temperate United States, poison dart frogs could almost be considered mythical creatures, a representative of deep dark jungles unreachable and far away, beautiful but potentially deadly animals. I had read about them in books and seen them on nature programs and suddenly here was one a foot away from me.

Excitedly, I began taking pictures and motioning to my companions to share my find. A passing instructor was verbally assaulted by me as I vigorously told her of our extreme good fortune in finding such an exotic animal.

“Neat.” She said, as she smiled politely.

She had, of course, seen thousands of these frogs, and of over the course of the next two weeks, I would too. But I didn’t know that at the time and had no frame of reference for what was rare or common in the region. Looking back, I was afterward probably a little embarrassed at my exhilaration at seeing what eventually proved to an abundant creature. I swore that if I were ever to return, I would act as if I’d been here before.

Fast forward nine years. The night we arrived at Palo Verde National Park, I spent some time exploring the edge of a nearby marsh. As the light from my flashlight careened around the landscape, a dull red circle reflected back at me. Freezing mid-stride, I realized I had caught the eyeshine of an American crocodile, Crocodylus actus, in the nearby water. This species is an interesting study in how animals may behave differently in varying regions. The same species occurs in southern Florida, and is generally considered a shy and docile creature. In Central America however, it’s known as a potential man-eater and is accordingly afforded substantial respect. I wasn’t too worried though, because large crocodiles prefer deeper waters, and the shallow marsh was populated primarily by juveniles, less than four feet in length. It was still exciting to know there were crocodiles nearby and within sight, as they were one of the species I wanted most to see, and have eluded me in previous attempts.

The next morning, my first at Palo Verde, I was awake early and back in the marsh photographing wetland birds including wood storks, roseate spoonbills, and black-bellied whistling ducks, among many other species.

After about twenty minutes my eye caught a familiar form less than twenty feet from where I was standing. A juvenile crocodile was basking motionless on some nearby mud and it had escaped my attention the entire time. To catch a glimpse of a crocodile was exciting enough, but for one to present itself for photographs was an incredible opportunity indeed.

Excitedly, I began filling the memory card of my camera with shots of the crocodile from various yet probably indistinguishable angles. When I accidentally got too close, the alarmed reptile retreated to the water and I took the chance to peruse my new pictures before breakfast, silently approving my own work. Arriving later at the dining hall, I eagerly showed them to all the students I passed. Several course instructors, when I eventually made my way to their table, were also subject to an impromptu showing of my new and expansive gallery of crocodile photographs.

“Neat.” They said, as they smiled politely.

This is part two of my travels through Costa Rica.

Friday, January 29, 2010

Return to Costa Rica

As my rain-delayed plane repeatedly circled around Charlotte, North Carolina, I cast increasingly frequent glances at my watch. The scheduled departure time for my connecting flight to Costa Rica was approaching rapidly.

It had been nine years since I was last in the country, nearly a decade. It’s unfortunate how steadfast attitudes to make plans for imminent returns dissolve over time. An engrossing and life-changing experience reduced to fuzzy memories seldom recalled.

Mexico, North America’s portal to first the tourist havens, then the jungles of Central America, and culminating in the majestic vastness of the Amazon rainforest, is in the United States Southwest. So, it’s natural for an East Coaster like me to abstractly consider Central and South America as far to the west. But, due to the curve of the continent, Costa Rica is actually a near straight shot south from Alabama or the Florida panhandle.

When my plane finally landed in North Carolina, I could count the minutes to my scheduled departure on one hand. I impatiently maneuvered around other passengers lazily removing their stowed baggage while carrying on inane conversations about who cares what and sprinted off the plane. I was hopeful but resigned to the knowledge that I’d probably be missing my flight. I took the chance that my departure gate hadn’t changed as I ran towards the concourse noted on my boarding pass.

Final boarding calls for my flight resonated over the airport’s public address system as I ran, my heart racing and chest burning. Out of shape from months of office work and my bad knee (differentiated from my good knee by a couple more dislocations) protesting, I ran to the counter as fast as I was able to manage. The agent, seeing me huffing and puffing, hurriedly asked me if I was headed to Costa Rica and I couldn’t believe my good fortune when he accepted my pass and told me he was glad I was there.

On the plane, I sunk into my seat, relieved and still out of breath. I had made it. I was safely on my connecting flight and on my way to Costa Rica. I couldn’t say the same for my luggage however, which wouldn’t join me until after I had already begun to settle into the wilds of the Pacific dry forest of Costa Rica.

For the next eight weeks I will be traveling through Costa Rica learning about the varied habitats and the organisms that can be found within them as I participate in a course offered by the Organization for Tropical Studies. At some sites, I will be staying in state of the art research facilities; at others, I’ll be isolated in the jungle and far from the nearest internet connection or cell phone tower. I will try to update this blog as I can, including information about what I’ve been up to, what I’ve learned, and what interesting wildlife species have been revealed.

Monday, January 11, 2010

Watch Out for Falling Iguanas

The southeastern United States has been hit with a cold front the likes of which it hasn’t seen in a long time. As I try to stay warm inside, my thoughts drift to the wild animals that depend on the temperature outside to regulate their internal temperature, the reptiles. In this area, and Florida in particular, it may get below freezing periodically but it doesn’t often stay this cold for this long; and it’s becoming difficult for some animals adapted to warmer temperatures.

Lately, there have been many news stories describing the plight of reptiles facing the bitterly cold weather. Some of the particularly entertaining reports describe Green Iguanas in Florida falling from trees at night and found on the ground in a sort of cold-induced coma the next morning. When brought inside to warm up, these comatose animals gradually regain consciousness. If they had been left outside however, there’s a chance they wouldn’t have recovered.

Why do these Green Iguanas seem so poorly equipped to deal with the cold? The answer is that Green Iguanas aren’t from the southeastern United States; they’re normally found in Central and South America, where they never had to evolve mechanisms to deal with very low temperatures. The animals we see in Florida are the descendants of released or escaped pets. These iguanas have thrived in the typically warm temperatures and established themselves throughout the Florida peninsula, particularly in the southern portions. In these regions, the climate is similar to what can be found in their native range. One difference though, is that can sometimes get a lot colder here.

As far as many animals are concerned, the critical difference between the southeastern United States and more tropical regions isn’t that it’s hotter in the tropics (although it often is), it’s that the tropics don’t experience the temperature fluctuations over the year that we do, as the seasons change. It’s these temperature fluctuations that the iguanas are unprepared for. There hasn’t been a freeze of this type in a few years, enough time for the iguana population to get fairly large, and now we’re seeing what happens when they experience weather unlike what their bodies are suited for.

It’s unpleasant to think of the iguanas dying (a good reason to never release unwanted pets) but it’s not considered a conservation concern, because they are not part of the native ecosystem. Exotic species in general may wreak havoc on local plants and wildlife and are therefore sometimes the subject of eradication campaigns. Nobody is too worried about the iguanas in Florida; they’re doing fine in their native range, where they belong.

On the other hand, some of our very own reptile species are having a hard time dealing with the cold as well. Wildlife rehabilitation centers up and down the coast are being overwhelmed by the number of cold-shocked sea turtles rescued over the last week or so. Unable to function in the cold water, over one thousand sea turtles have shut down and floated to the ocean surface, and rescuers have been busy trying to save as many as they can. Although many sea turtles we usually see in the summer probably migrate to warmer waters during this time of year, there are still many that hang around, and these are the animals that are now succumbing to the cold. Most of these turtles probably won’t require too much attention at the rehabilitation centers, just a warm place to revive themselves and wait out the cold snap. Still, space and resources are at a premium.

So what, you might say. Sure, it’s unfortunate the sea turtles are in trouble, but that’s nature’s way. Often, I’m inclined to agree with this sentiment, but these animals are highly endangered already, and not for natural reasons. Sea turtles, of which there are five species to be found along the southeastern United States coastline, have lost much of their nesting habitat due to development, been killed by the thousands in shrimp nets and on commercial fishing lines, and died en masse by ingesting our garbage (mostly plastic refuse that looks like their jellyfish prey). Together, these threats (and some others) have combined to make their situation a perilous one.

Although they may be facing a natural threat now, our previous actions have put these turtles in a position wherein they are less able to respond to these occasional natural events. Many would argue it’s our responsibility to do everything we can to restore sea turtle populations to healthy numbers; I’d be inclined to agree.

To donate to a couple of the centers that are taking in cold-stunned turtles, visit:
Georgia Sea Turtle Center, Jekyll Island
Mote Marine Laboratory, Sarasota, Florida
Clearwater Marine Aquarium, Clearwater, Florida

Green Sea Turtle pictures are courtesy of Shannon Hackett

Friday, January 8, 2010

Mommy Dearest

It was a dark summer night, I was up to my knees in a southwestern Georgia pond, and I just saw the scariest thing I could imagine. I was there trying to figure out how much effort was needed to catch a large sample of water snakes for a future study and my eyes were focused on keying into their serpentine shapes along the shoreline. But when I caught sight of a large mound of sticks and dirt just above the water’s edge, that’s when I started to get nervous.

I slowly and instinctively turned and looked out across the center of the open pond and, just as I had suspected, the light from my headlamp reflected back at me from dozens of little yellow eyes.

I had stumbled across an alligator nest and the small pond was covered in recently hatched animals. It wasn’t these baby alligators I was afraid of though, it was the mother, assuredly somewhere close, watching my every movement. And mother alligators are very protective.

When a female alligator feels her time is near, she’ll laboriously construct a mound of mud and debris and lay her eggs in the middle of it. After carefully covering up the eggs with more mud and plants, she’ll retreat to the nearby water and wait. If a raccoon or other potential egg predator ventures too close, she’ll torpedo from the water hissing with mouth agape. It’s an intimidating display, and an effective one. But her motherly duties don’t stop there.

When the baby alligators hatch in late August, they begin to emit a guttural chirping noise. These chirps alert the mother alligator of the new arrivals and she starts to excavate them from the nest. After uncovering the youngsters, she’ll delicately pick them up in her mouth and carry them to the nearby water. The babies will stay with the mother for up to a year and their chirps, which they’ll utter when distressed, continue to inspire a prompt protective response from the dedicated parent.

Alligators make excellent parents (at least the females do), and that makes them unique among reptiles. Take turtles for example, females will lay their eggs in a nest some distance from the water, cover them up, and then never have anything to do with her young again. Most reptiles will lay their eggs (or in the case of some groups, give live birth), and let them fend for themselves. One interesting exception includes some pythons; females will coil themselves around their clutch of eggs and shiver to generate warmth.

But when it comes to protecting the young after they’ve hatched or been born, alligators are apparently a reptilian exception. They’re the only ones seeming to demonstrate bona fide parental care, parental care being the term used in scientific circles. What is parental care anyway? Mammals nurse their young, birds bring food back to the nest for their young; alligators don’t do anything like that at all. But, would anybody doubt that chasing away potential predators from their babies is taking care of them? It’s probably best to consider parental care as any behavior that increases the chance of survival among offspring.

What’s more, it’s probably safe to say this behavior is due to a genetic attribute, at least in alligators. Alligators that are good mothers give birth to young that carry this same genetic disposition, those young have a good chance of surviving to adulthood because they’re taken care of, and these young can then breed themselves and take care of their young, and so on. If we don’t think that parental care is due to an animal’s genes, what alternative is there? That alligators learn to take care of their young? That seems to be an unlikely scenario. If we accept that behavior can be influenced by an individual’s genes, it’s easy to see how a beneficial behavior like parental care can evolve.

So, to include alligators among the group of animals that exhibit parental care, we must broadly define parental care as simply any behavior that increases the survival of young. And if we do this, we may need to reexamine the other reptiles we previously dismissed. For example, let’s take a look at the turtle we mentioned earlier, the turtle that just lays her eggs and leaves. If some females have a genetic predisposition to build their nests in areas where predators are unlikely to find them, such as under dense vegetation, does that count as parental care? It might.

Another interesting example includes the rattlesnakes we have in the region. Many naturalists have observed female rattlesnakes that have recently given birth surrounded by their new babies. These snakes may be found together for some period of time, crawling over each other in their refuge, usually some sort of underground shelter. Is the female sticking around because the babies are safer when she’s there? Or maybe the birthing process was so exhausting that she needs a few days to recuperate enough energy to leave. It might not matter in this case, in both scenarios the end result is the increased survivorship of the young, therefore, it’s parental care! Even if it does sometimes backfire.

Behind the oblivious snake researcher,
note the alligator eyes reflected by the camera flash.
These thoughts weren’t of much concern to me as I wading through the water that dark summer night. I managed to make it back to dry land without pissing off the mother alligator; I even found and caught a few water snakes while simultaneously keeping one eye peeled for any sign of an impending attack. I decided though, I could find different wetlands for further study.

Alligator photos courtesy of Matt Greene.
Photograph of yours truly courtesy of Sean Sterrett.

Friday, January 1, 2010

This Is Why You Should Never Kill A Blacksnake!

It ain’t easy being a snake. If people don’t run away screaming at the sight of you there’s a good chance it’s only because you’re about to be killed with a shovel. For serpents, your average citizen of the southeastern United States is very hard to please. But in the eyes of many, some species at least do have one redeeming quality, that being they eat other snakes. The lives of many kingsnakes, for example, have been spared because the species is ophiophagus (this is the scientific term for individuals or species that eat snakes; I myself have been known to be ophiophagus once during a camping trip a few years ago, but that’s another story).

In addition, another ophiophagus snake around here is the Indigo Snake, Drymarchon corais couperi , famous in particular for their ability to eat rattlesnakes. Pit vipers may actually even be their preferred prey. Since rattlesnakes have a shot at being the most reviled organisms on the planet, indigo snakes, in turn, enjoy considerable popularity (although this relative popularity has not been enough to keep populations from declining precipitously over the last few decades). The indigo snakes’ rattlesnake-eating behavior is on full display in an e-mail I’ve received several times, often entitled something along the lines of, “This is why you should never kill a black snake”.

The series of photographs shows a large indigo snake, identified by its uniform dark body, orange-tinted chin, and dark line running below its eye, consuming a Western Diamondback Rattlesnake, Crotalus atrox. Many have identified the snake in these pictures as a kingsnake, Lampropeltis getula, which it certainly is not. Although kingsnakes may also eat rattlesnakes, they will typically have white or yellow chains or bands along the length of their body. The rattlesnake, sometimes erroneously identified as the Eastern Diamondback Rattlesnake, Crotalus adamanteus, is easily identified by the black and white striped tail that is characteristic of the western species. Since it's a western diamondback rattlesnake, we know that this picture did not originate in the southeastern United States, where they do not occur. We also know that this can't be an Eastern Indigo Snake, Drymarchon corais couperi, because they aren't found where Western Diamondback Rattlesnakes live. This must be a Texas Indigo Snake, Drymarchon corais erebennus. If the picture was taken in the United States, it must be from south-central Texas, the only area in the country where the species occurs (both species also occur in Mexico).

Many commonly inquire how Indigo Snakes are able to safely consume rattlesnakes, dangerous predators in their own right. I don’t think it’s accurate to suggest Indigo Snakes are completely immune to rattlesnake venom, but it’s probably safe to say they are less susceptible to its effects than other animals. When a prey snake is located, an Indigo Snake will grasp its head and chew it into oblivion (demonstrated in the below picture) before swallowing it whole.

So long and Happy New Year!