Friday, November 25, 2011

Is the South Florida Rainbow Snake Really Extinct?

A Georgia Rainbow Snake (courtesy D. Stevenson)
A few weeks ago I wrote about how the South Florida Rainbow Snake, of which there are only a handful of known specimens (and not to be confused with the "normal" Rainbow Snake), was officially declared extinct by the United States Fish and Wildlife Service (USFWS).

Not so fast, say the Center for Snake Conservation and the Center for Biological Diversity. These organizations claim that the USFWS made their official announcement before enough was done to confirm the snake's absence. Ideally, the feds should have carried out multiple, intensive, surveys before concluding that the animal no longer existed, but they didn't do that. If there are still some South Florida Rainbow Snakes left, the two conservation organizations argue, they deserve to be protected, not written off by being declared extinct before a rigorous search was even conducted. To encourage people to obtain evidence of the continued existence of the South Florida Rainbow Snake, the Center for Snake Conservation and the Center for Biological Diversity are offering a $500 reward for official documentation.

I completely agree that the USFWS should make sure that a species is truly extinct before officially declaring it as such, but I'm skeptical that the animal is going to turn up now. Finding any Rainbow Snake, let alone the group of Rainbow Snakes in South Florida, is like finding the Holy Grail of herpetology. Although there may not have been official surveys to find the snake in South Florida, amateur naturalists and field-herping enthusiasts have made many trips and spent countless hours searching for the animal and none have been found since 1952. For these die-hards snake-searchers, the value of the bragging rights that would be secured by finding a South Florida Rainbow Snake would greatly surpass $500.

Another Georgia Rainbow Snake
What happens if the South Florida Rainbow Snake is still around? Chances are, its long-term prognosis is not very good. If the animal is not extinct, it's hard to believe that it still exists in any meaningful way. In other words, even if there are still a couple of animals left, it's hard to believe that they are part of a population with enough individuals to sustain itself over the long-term.

Occasionally, species that were officially declared as extinct are found to still be around after all, the Ivory-billed Woodpecker is the latest high-profile example. In fact, over the last 122 years, 351 "extinct" species have been rediscovered. These stories get a lot of press and people start to feel good and excited. But, even if a few individuals of a particular species still exist, that doesn't mean that the species is in the clear. Often, it's just a delay of the inevitable. As a recent study indicated, the vast majority of "rediscovered" species are still highly threatened and are likely to be truly extinct very soon, regardless of their official status.

I could be wrong, and I would happy if that were the case. Even where we know there are populations of Rainbow Snakes, they are extremely hard to find. This is likely because they spend most of their time under water and hidden among aquatic vegetation and tree roots. It is very possible there are still some swimming around and hunting for eels in the swamps of South Florida. So, everybody get outside with your camera and check out Fish-Eating Creek, you may end up winning $500 and rediscovering an "extinct" species. Even if you don't find Rainbow Snakes you're likely to find something worth seeing. I would be interested to hear of any attempts to find South Florida Rainbow Snakes, past or present, successful or not, and hear how the habitat looks.


Relevant Scientific Articles

Scheffers BR, Yong DL, Harris JB, Giam X, & Sodhi NS (2011). The world's rediscovered species: back from the brink? PloS one, 6 (7) PMID: 21818334

Fitzpatrick, J. (2005). Ivory-billed Woodpecker (Campephilus principalis) Persists in Continental North America Science, 308 (5727), 1460-1462 DOI: 10.1126/science.1114103

Dalton, R. (2006). Ivory-billed woodpecker extinct after all? news@nature DOI: 10.1038/news060313-14

Thursday, November 24, 2011

This Thanksgiving, Don’t be a Hog (Nosed Snake)

   Many of us tend to overeat during Thanksgiving, but we've got nothing on snakes, some of which might occasionally eat something larger than they are. When eating a large meal, consuming something bigger than yourself isn’t simply a matter of whether you want to do it; there are also serious physical concerns. In other words, even if you wanted to eat more than your body weight in food (on some Thanksgiving pasts, I’ve certainly given it a fair shot), how can you possibly fit it into your body? Something that weighs more than you do is probably larger than you, and it takes some imagination to figure out how you can fit a large object into a smaller object. One potential is by chewing your food very well, so that you can maximize your ability to arrange your food once you’ve swallowed it. Another option is to select very dense food to eat because a smaller amount of food will weigh more than other, less-dense items. I’ve had some stuffing that might have qualified.

   When eating large prey, snakes have an advantage. Most people know that the unique morphology of a snake’s jaw allows it to go big at mealtime. But, there is a common misconception that snakes can dislocate their jaw, this is not entirely true. What’s unique about snakes is that their lower jaws aren’t connected to each other at the front by bone (like ours are) they are connected by a ligament. This gives them tremendous flexibility in moving their jaws when swallowing food.
A Very Young Hognosed Snake
(not the one mentioned on left)

   But, even though snakes can eat relatively large meals, that doesn’t mean they eat things larger than they are. In fact, a recent study suggested that nobody had ever documented a snake eating something larger than itself, at least when the meal was a frog.

   So, although I’ve seen a bunch of snakes so full of food that they look they’ve been blown up like a balloon, when I trapped a small Eastern Hog-nosed Snake in a bucket in the Florida panhandle, I knew it took the cake. Actually, in this case it looked like it had taken the cake and eaten it.

A Bucket Trap (Note the Pigmy Rattlesnake)
   In 2009 and 2010 I was trapping animals in longleaf pine forests to characterize the wildlife populations there and determine how they responded to different forest management strategies. The type of trap I used is relatively simple; I put aluminum flashing in the ground and bury buckets alongside this makeshift wall. As animals crawl around the ground, they hit the fence and fall into a bucket. It was possible that the Hog-nosed Snake I found had eaten a big meal and then been trapped, but it was so fat I don’t think it would have been moving around much. My guess is that there was a large frog in a bucket, and the snake had crawled in after it.

   I gingerly held the snake and gently placed it into a pillowcase while being careful not to stress it out. When a snake with a recent meal is stressed, they will often regurgitate. It’s likely that the snake can crawl away faster without the added burden. In any case, despite my gentle touch, the small snake did end up throwing up their prey, a Spadefoot Toad. The toad was very much alive.

Spadefoot Toad
   Because snakes can’t chew their food, they swallow it whole. And many snakes don’t constrict their prey before swallowing it, they just start swallowing. That means the prey is often alive when they go down the hatch. Hog-nosed snakes are such a snake. They are frog specialists and they don’t constrict, and that means that if you catch a recently-fed snake, there’s a reasonably good chance that it will cough up a living, breathing frog.

   In this case, I was able to weigh both the toad and the snake, and, as I suspected, the toad actually weighed more than the snake. But, not by much, the toad (36 grams) weighed 1.06x more than the snake (34 grams). After talking to a friend of mine, he noted he had once seen something similar. In his case, he had found a 6 gram Eastern Hog-nosed Snake that had eaten an 8 gram Southern Toad (a ratio of 1.33!). So, if you hope to emulate a Hog-nosed Snake today and eat more than your weight in mashed potatoes and cranberry sauce, just remember that the stuffed snakes we caught weren’t able to keep their meals down. You probably won’t either.

Happy Thanksgiving

Relevant Scientific Articles

Toledo, L., Ribeiro, R., & Haddad, C. (2007). Anurans as prey: an exploratory analysis and size relationships between predators and their prey Journal of Zoology, 271 (2), 170-177 DOI: 10.1111/j.1469-7998.2006.00195.x

D. A. Steen, G. G. Sorrell, N. J. Paris, K. J. Paris, D. D. Simpson, & L. L. Smith (2010). Heterodon platirhinos (Eastern Hog-nosed Snake). Predator/prey mass ratio Herpetological Review, 41

Friday, November 18, 2011

Friday Roundup-Eating Animals to Extinction and Yes, Virginia, There is a Copperhead

An Alabama Copperhead
1. This just in: News Flash. Snakes exist in Virginia. Better get them before they get you.

2. Those Who Do Not Learn From the Past... Biologists, and even conservation biologists, historically had some curious views regarding their study organisms, views that seem very odd today. The classic example, to me at least, is that of Sir Alfred Russell Wallace (1823-1913), a pioneering biologist. When studying orangutans in Borneo, he describes following these magnificent animals through the treetops, shooting them over and over until the large beasts finally succumbed to multiple gunshots. He killed 29 in one stay. We now know that orangutans reproduce very slowly (and are endangered); their populations decrease in numbers over time if many animals are killed. In other words, not only are the animals that are killed removed from the population, but the surviving animals don't produce enough offspring to make up for these deaths. However, Wallace never claimed to be conserving these animals, only studying them (for an excellent book on Wallace's pioneering studies, check out: Where Worlds Collide: The Wallace Line (Comstock Books).
  On the other hand (and closer to home), William Temple Hornaday was a pioneering conservationist in North America. In 1905, he founded the American Bison Society, an organization dedicated to saving the bison from extinction.

   We are already familiar with the plight of bison in the United States (although commonly referred to as buffalo, buffalo are actually a group of animals found in the Old World, including Africa and Asia). We learn early on in school about how vast herds of these animals in the midwest plains were eventually hunted to oblivion (it is hard to grasp how common these animals once were, but the mountain of skulls on the right gives you an idea; imagine the experience of witnessing a herd of this many animals).

   But, bison actually ranged far outside of the midwest plains. They were once found in New York and all along the Appalachian Mountains south to Florida. They were found as far north as northern Canada but also in central Mexico. So, although we are all told stories to make us appreciate how there were once vast herds of bison in the United States, even these stories don't come close to communicating that bison were a major part of the natural world across the entire continent. Because much of the United States is now missing bison, it's almost as if we live in a sanitized version of what nature should really look like.

  In any case, bison were already extremely rare by 1886, when William Hornaday mounted an expedition to find the animal he fought to save. Perhaps to his dismay, he realized the animals were virtually absent. But, he did not give up in his search. Eventually, he found a small group of impressive beasts clustered together, perhaps we can think of it as a tiny herd. One might imagine his elation, after struggling to find any evidence that the animals even existed anymore, to have found these animals.

  It is harder to understand his motivation behind what he did next. He shot them all. Robert Krulwich writes an excellent essay of the subject. But, he is at a loss regarding how to explain what was going on in William Hornaday's mind that day. How do you explain the inconsistency between what William Hornaday fought for and what he did? Perhaps there was a disconnect between saving the bison as a species (which is an idea) and killing individual animals (which is an action). It's crucial to realize that what we do and how we act is what makes conservation happen, not just abstract ideas.

 It's easy to assume that we wouldn't make the same mistake again. How could we ever allow a huge beast, a giant mega-herbivore, to go extinct on our watch? Well, we do it all the time. Just in the last few weeks came news that there are no more Javan Rhinoceros is Vietnam and no more Western Black Rhinos anywhere in the wild. I hope you got a chance to see them.

3. A Lizard a Day Keeps the Doctor Away? Earlier this year I spent some time in the Florida Keys while I helped out on a python research project. The nights at our peaceful beachside cabin were occasionally interrupted by a odd hiccuping-chirp from outside.  Tokay Geckos prowled the walls and the trees, calling to attract mates (you can hear one disturbing a family here). They are not native to North America, the animals we heard were probably descendants of escaped pets. This species is normally found in Asia, and it's hard to imagine this Florida pest being in trouble in its native range, but that's exactly the case. Traditional medicine suggests Tokay Geckos have useful disease-fighting properties. These claims haven't been backed up by scientific studies, but that doesn't stop people from harvesting the lizards. Fortunately, the trend was noticed early, before Tokays became critically endangered or extinct. Maybe it's not too late to change our ways.

4. Let's End on a High Note: There is a lot to be pessimistic about. But, there are still lots of fascinating animals patrolling their habitats in the wilderness and interacting with other species just as they always have. The Deep Sea News Blog provides some awesome footage of a giant ray gliding through the water and a school of yellow angelfish that rush to clean the beast. Check it out.

Relevant Scientific Articles

ROSTLUND, E. (1960). THE GEOGRAPHIC RANGE OF THE HISTORIC BISON IN THE SOUTHEAST Annals of the Association of American Geographers, 50 (4), 395-407 DOI: 10.1111/j.1467-8306.1960.tb00357.x

Erik Meijaard, Alan Welsh, Marc Ancrenaz, Serge Wich, Vincent Nijman, & Andrew J. Marshall (2010). Declining Orangutan Encounter Rates from Wallace to the Present Suggest the Species Was Once More Abundant PLoS ONE, 5 (8)

Friday, November 11, 2011

Friday Roundup-Hero Dogs and a Mouthful of Slime

Here are a couple items that caught my attention this week.

1. Rattlesnakes From Abandoned Lots Invade Neighborhood, Terrorize Residents. This sounds like it could be the premise of a reasonably entertaining horror movie. Residents of Port St. Lucie, Florida are convinced that Eastern Diamondback Rattlesnakes are thriving in their neighborhoods because there are too many vacant and abandoned lots. This might be somewhat of an overstatement. Eastern Diamondback Rattlesnake populations are thought be in decline throughout most of their range. If the only thing Eastern Diamondback Rattlesnakes needed to thrive was for people to stop mowing their lawns, the United States Fish and Wildlife Service wouldn't have been petitioned to protect them.

  But, the fact remains that there are Eastern Diamondbacks occasionally showing up where people don't want them. This week, a seven-foot rattlesnake bit a pit bull in someone's yard. Did you do a double-take when you read the rattlesnake was seven feet long? Me too...We'll come back to that in a moment.

  This isn't the first story in the last few weeks to describe a dog being bitten by a venomous snake. And, like these other stories, the owner said that their life had been saved by their heroic dog. I think it may require some imagination to believe that these people were about to be killed by a snake until their dog saved the day (I should make clear here that I wish all dogs involved a speedy recovery and even offer some tips here about how to reduce the chance of your dog getting bitten). Why is it unlikely any human life was in danger? We never even see most of the snakes that are in our yards or under our houses, just because a dog found one and got bitten doesn't mean any lives were saved. Plus, most snake bites occur when people try to handle or kill the snake. The best way a dog could save their human-companion from getting bitten by a serpent is to keep them from messing with it.

This Australian veterinarian has an interesting hypothesis. He says dog-owners shouldn't kill snakes in front of their dog (I assume this happens often when a dog finds a snake), because the dog may learn to try to kill snakes on their own. Perhaps this is a concern when dog-owners get excited after their dog finds a snake, it is easy to imagine that the dog perceives the excitement as a reward.

What's the morale of the story? If you want to avoid getting bitten by a venomous snake, don't rely on hero dogs; train your dog to avoid snakes and do not handle, capture, or attempt to kill snakes yourself.

  Whenever I see a newspaper article about a seven-foot rattler, I know it's a relatively safe bet that the reporter simply took someone's word regarding the length of the snake. It's a common enough occurrence despite many people having surprisingly outrageous ideas regarding how to estimate a rattlesnake's size. We know a seven-foot rattlesnake would be an exceptionally rare and absolutely huge snake. It's not something many people will ever see in their lives. Two days after the original article, a follow-up story now mentions that the snake is three feet long; there is no explanation regarding how the snake shrank four feet in 48 hours.

2. It Turns Out Hagfish Don't Taste As Good As They Sound. Hagfish are an ancient group of animals that live on the ocean floor. For a long time, most people assumed that these creatures, which look a lot like eels, were scavengers, foraging on whatever dead things they could find. But, it is hard to say anything about the natural history of these animals with certainty because it's almost impossible to observe them where they live, i.e. the ocean depths. In this paper, researchers use a bit of modern technology to shed some light on these mysterious creatures. By dropping some bait (and a video camera) into the ocean, a few New Zealand and Australian researchers were able to film some surprising behavior. First are all the attempted predation attempts on hagfish as they swim around the bait. Hafish are interesting in that they are lined with slime pores which exude, you guessed it, a slimy substance. It's long been assumed that this slime deters predators. Now, we can watch this defense mechanism in action. It's a must see. Second, they filmed a hagfish diving into a burrow and extracting a small fish to eat, conclusively demonstrating that they aren't solely scavengers. Check it out.


Much of what I write is based on my experience in the field, however I also rely on the research of others, citations of some relevant scientific articles are below.

Vincent Zintzen, Clive D. Roberts, Marti J. Anderson, Andrew L. Stewart, Carl D. Struthers, & Euan S. Harvey (2011). Hagfish predatory behaviour and slime defence mechanism Scientific Reports, 1 (131)

Friday, November 4, 2011

Friday Roundup-Recent Articles and Blogs of Interest

There are often articles and blogs that catch my eye but I am unable to comment on or write about because I am either preoccupied with other things or I can't come up with enough material to justify an entire post. So, I'd like to periodically bring your attention to some recent articles that you all may find of interest. I would like to say that this will be a weekly feature, but I don't quite want to commit myself to that. Suffice it to say I will try.

1. Huge Python Found in Everglades After Feasting on Deer. As you may be aware, there is now an established population of Burmese Pythons living in South Florida, particularly in the Everglades region. This species is not native to the United States, they are from Asia. But, they were brought over here for the pet trade. How they became established in South Florida is anyone's guess, but the general consensus is that some of these snakes escaped, started breeding, and now they have become firmly entrenched. There is a lot of concern regarding what kind of effect these pythons may have on the native ecosystem, we know they certainly eat a lot of other animals (including deer, alligators, you name it). I spent a week assisting on a python project earlier this year and I hope to write about it soon.

2. Are Eastern Diamond-backed Rattlesnakes Endangered or Not? Recently a few organizations petitioned the United States Fish and Wildlife Service to list the Eastern Diamondback Rattlesnake under the Endangered Species Act. Although the process by which a species becomes federally protected following a petition can be complicated, it is summarized here. Basically, after receiving a petition the USFWS determines whether or not the petition has merit. If it does have merit, then the next phase begins: a year-long scientific review. If the science supports listing, this conclusion is then reviewed by experts and the public is allowed to comment. If the species clears all these hurdles, it is then federally listed. This takes a long time and it's not unusual to wait years for a final ruling. Sometimes the USFWS decides a species should qualify as federally threatened or endangered, but they are unable to make this official due to budgetary limitations. These species are then designated as Candidate Species (this is what happened recently to the Gopher Tortoise).

  Recently the USFWS updated its list of Candidate Species. Since the Eastern Diamondback Rattlesnake is still very early in the petition/listing process, it was not yet at the stage when it would even be considered for inclusion on this list. Yet, some in south-Alabama started celebrating a little early. Since the Rattlesnake wasn't on the list of Candidate Species, this was interpreted to mean that the USFWS decided it wasn't rare. Well, this isn't how the system works. Fortunately, the newspaper in question subsequently printed a correction of sorts.

3. Monster Myth Origins. I know I am a little late for Halloween-themed articles. But Scientific American recently compiled a great list of monster and creature-related blog posts. I particularly enjoyed, "A Natural History of Vampires". How are these articles relevant to this blog? Well, a few of them discuss how a misunderstanding of biology and natural history (including human natural history), have led to some fascinating myths. This is not unlike what we have seen for some of our wildlife, such as the maligned and misunderstood Cottonmouth.

4. Finally, an Unusual Obituary. A celebrity snake-of-sorts passed on recently, and I stumbled across a fairly touching tribute. It's an animal we don't often see celebrated, a Cottonmouth. Not only are these animals incredibly unpopular among the general public, but this particular animal had actually killed someone. But, suffice it to say that the person that was killed had decided to engage in some very risky snake-human interactions.