Friday, January 18, 2013

The American crocodile in Portete Bay, Colombia

The American crocodile, Crocodylus acutus, has undergone population declines over much of its distribution due to human persecution, overexploitation and habitat loss. The species remains critically endangered in some countries such as Colombia where the lack of detailed surveys on its ecology and distribution constitutes a major barrier to the development of effective conservation strategies.Espinoza et al. (2012) conducted a three-year capture-recapture study to investigate the demographic status of the American crocodile and to identify environmental variables likely to influence its distribution in Portete Bay (Colombia). They estimated the crocodile population to be relatively small (< 140 animals), to include very few adults, and to demonstrate a very strong deficit in juvenile females . Both mean air temperature and relative humidity were positively correlated with the number of sightings. In contrast, mean water salinity was found to decrease the probability of observing a crocodile, presumably due to juvenile preference for low salinity areas. The results suggest that the Portete Bay American crocodile population is at risk and may require human intervention to assure its persistence.

MARA I. ESPINOSA, M.I,  BERTIN, A.,   GÓMEZ, J.,  MEJÌA, F.,  GUERRA, M., BAEZ, L., GOUIN, N., PATIÑO, E. 2012. A three-year mark-recapture study in a remnant population of
Crocodylus acutus Cuvier in Portete Bay (Guajira, Colombia). Guyana 76:52-58.

Tuesday, January 15, 2013

Sonoran Desert Reptiles & Garbage

WDR, Crotalus atrox. JCM
Ocean garbage patches get a lot of attention, but a lot of trash is blowing across some of the most treasured and remote parts of America's desert wilderness, according to a new study out of the University of Arizona.

Biologist Erin Zylstra mapped and added up all the wind-dispersed plastic trash bags and latex balloons in two protected parts of the Saguaro National Park in Arizona. She was surprised to discover that these particular kinds of very mobile trash outnumbered desert tortoises and western diamondback rattlesnakes. Like in the oceans, the bags and balloons pose potential threats to wildlife.

We were spending a lot of time surveying and we started to notice a lot of trash," Zylstra said. "Balloons are everywhere, once you start to look." The balloons were often found in clumps, tied with string and can become so degraded they look almost like lichens stuck to rocks, she explained.

"Western diamondback rattlesnakes are pretty common in the areas we studied," she said. "The fact that there is considerably more balloons than snakes was kind of shocking."

Like trash on the oceans and in coastal areas, winds seems to play a role in where trash collects in the desert as well. Zylstra found that the wind-blown bags and balloons in the two study areas, situated on opposite sides of the city of Tucson, reflected seasonal wind patterns in the region.

Because balloons are made of latex, they eventually decompose, although how long that takes in the desert is unknown. Plastic grocery bags, on the other hand, only break down if they are exposed to sunlight. Even then they only break into smaller pieces and become part of the water and soils, without actually changing into other compounds. That means they could mix with the water and food ingested by wild animals.

"Nobody really knows where those pieces of plastic bags end up," Zylstra said. "It's not known whether they have toxic effects." One possible concern is that the bags could end up in the few desert watering holes that animals of all kinds must share.

Another potential hazard for wildlife is the strings that come with the bunches of balloons, said Don Swann, a National Park Service biologist who works at Saguaro National Park.

"We see plastic bags and balloons in very remote places," confirmed Swann. This study finally put numbers on the amount of trash, which is very helpful, he said. It also showed how efficiently trash surveys can be incorporated into biological surveys.

"It's really great when researchers think outside the box," said Swann. "They can come up with insights that are valuable to us."

The study, due to be published in the February 2013 issue of Journal of Arid Environments, grew out of surveys Zylstra was conducting on those same two reptile species as part of her studies at the University of Arizona, where she is now a doctoral student.

Zylstra used distance-sampling methods to quantify density of wind-dispersed trash in two protected areas of the Sonoran Desert in southern Arizona. The densities of plastic bags ranged from 5.6/km2 to 35.4/km2, and densities of balloon clusters ranged from 39.2/km2 to 62.7/km2. The density of balloon clusters was greater than the density of desert tortoises, Gopherus morafkai, and western diamond-backed rattlesnakes, Crotalus atrox, in both study areas. Results provide evidence that wind can disperse substantial amounts of trash, more than 2 km into protected natural areas and suggest that accumulation of trash poses a potential threat to desert ecosystems.

Zylstra, ER. 2013. Accumulation of wind-dispersed trash in desert environments. Journal of Arid Environments 89:13-15.

Monday, January 14, 2013

Clues to the evolution of salt tolerance in mud snakes

A. The Chinese mud snake, Myrrophis chinensis. B.  The Kerala mud snake, Dieurostus dussumierii
Photo credit A.  You Chugwei; B. A. B. Kumar.

Salt tolerance has evolved a limited number of times in extant snakes: once in the file snakes (acrochordids); at least twice in the front-fanged sea snakes (once in the egg-laying sea kraits and one in the live bearing sea snakes); at least twice, possibly more in the natricids (North America and Europe); at least once in the South America dipsidids, and at least once in homalopsids. The total number of living snakes inhabiting saline environments is approximately 110 species comprising only 3% of extant snakes. Remarkable when you consider 70% of the Earth's surface is covered with marine habitats.

In a recent paper published in Systematics and Biodiversity Kumar et al. (2012) found  the freshwater Chinese Mud Snake Myrrophis (formerly Enhydris) chinensis and the Kerala Mud Snake Dieurostus (formerly Enhydris) dussumierii are sister species. This relationship provides potential insight into the evolution of salt tolerance in the homalopsid snakes. The morphological similarity and geographical proximity of the Chinese Mud Snake and the coastal (brackish water and marine) Bennett's mud snake (Myrrophis bennettii) in southern China strongly suggest a close relationship between these species, but its DNA was not available for inclusion in the study. Myrrophis bennettii can survive in salt water for a period of time that may range from days to weeks. It is unknown if they have salt glands or use behavioral osmoregulation (moving from salt water to freshwater when they get thirsty), but a facultative salt gland cannot be ruled out. Dunson and Dunson (1979) described a facultative salt gland in the homalopsid genus Cerberus from Pulau, Micronesia.

However, no evidence of a salt gland has been found in members of the Enhydris clade (E. enhydris E. chanardi,  E. innominata, E. jagorii, E. longicauda, and E. subtaeniata) and preliminary observations suggests they are quite sensitive to salt water and die within a few days or less when exposed to full sea water. However, Bennett's mud snake and the Kerala mud snake are both salt tolerant, found in brackish and marine habitats, and separated by a straight line (over-water over-land) distance of more than 3300 km; following the coastline the distance is much greater, more than 15,000 km. Given the close relationship inferred between Bennett's mud snake and the Kerala mud snake it seems unlikely that salt tolerance evolved independently in the geographically distant species.

Members of the homalopsid clade are generally thought to have relatively poor dispersal abilities with even small increases in elevation posing significant barriers to movement and thus gene flow for most species. With few exceptions homalopsids are restricted to lowland habitats and seem to be incapable of ascending small waterfalls, navigating rapids or making long-distance overland movements. Thus following the coast is likely the path of dispersal for homalopsid snakes if they are, in fact slat tolerant. Kumar et al propose a hypothetical Asian coastal lineage, the includes the ancestor to Bennett's mud snake  and the Kerala mud snake that evolved salt tolerance in Indochina or the adjacent Sunda Shelf. The species or its descendants then followed the tropical coastline of Asia where in entered river deltas and coastal swamps and evolved into many of the homalopsid species we see today.
A map that shows the homalopsid snakes that are possible candidates for belonging to the Asian coastal clade.
Previous research placed the most recent common ancestor for the Chinese mud snake and the Enhydris clade in the middle Miocene (16 Ma). The Miocene was a period of greatly fluctuating sea levels with many highstands that were 25–35 m above current levels, and lowstands in the late Miocene that were 30–40 m below current levels.Changing sea levels could have  exerted strong selection pressures on coastal and marine snakes with highstands forcing coastal snakes that were not salt tolerant or only slightly salt tolerant further inland where fresh water was more readily available. While lowstands would increase the width of the
coastal plain, increasing the area available for colonization by lowland species.

Kumar, A.B.,  Sanders, K.L., George, S. and Murphy, J.C. (2012): The status of Eurostus
dussumierii and Hypsirhina chinensis (Reptilia, Squamata, Serpentes): with comments on the origin of salt tolerance in homalopsid snakes, Systematics and Biodiversity, 10:479-489.

The backbone of Ichthyostega

Scientists have been able to reconstruct, for the first time, the intricate three-dimensional structure of the backbone of early tetrapods, the earliest four-legged animals. High-energy X-rays and a new data extraction protocol allowed the researchers to reconstruct the backbones of the 360 million year old fossils in exceptional detail and shed new light on how the first vertebrates moved from water onto land. The results were published today, 13 January 2013, in Nature.

The international team of scientists was led by Stephanie E. Pierce from The Royal Veterinary College in London and Jennifer A. Clack from the University of Cambridge. It also comprised scientists from Uppsala University (Sweden) and the European Synchrotron Radiation Facility ESRF in Grenoble (France).

The tetrapods are four-limbed vertebrates, which are today represented by amphibians, reptiles, birds and mammals. Around 400 million years ago, early tetrapods were the first vertebrates to make short excursions into shallower waters where they used their four limbs to move around. How this happened and how they then transferred to land is a subject of intense debate among palaeontologists and evolution biologists.

All tetrapods have a backbone, or vertebral column, which is a bony structure common to all other vertebrates including fish, from which tetrapods evolved. A backbone is formed from vertebrae connected in a row - from head to tail. Unlike the backbone of living tetrapods (e.g. humans), in which each vertebra is composed of only one bone, early tetrapods had vertebrae made up of multiple parts.

"For more than 100 years, early tetrapods were thought to have vertebrae composed of three sets of bones - one bone in front, one on top, and a pair behind. But, by peering inside the fossils using synchrotron X-rays we have discovered that this traditional view literally got it back-to-front," says Stephanie Pierce who is the lead author of the publication.

For the analysis, the European Synchrotron Radiation Facility (ESRF) in France, where the three fossil fragments were scanned with X-rays, applied a data extraction method to reveal tiny details of fossil bones buried deep inside the rock matrix. The fossilised bones are embedded in rock so dense it absorbs most of the X-rays. “Without the new method, it would not have been possible to reveal the elements of the spine in three dimensions with a resolution of 30 µm”, says Sophie Sanchez, a co-author of the publication, from Uppsala University and the ESRF.

In these high-resolution X-ray images, the scientists discovered that what was thought to be the first bone - known as the intercentrum - is actually the last in the series. And, although this might seem like a trivial oversight, this re-arrangement in vertebral structure has over-arching ramifications for the functional evolution of the tetrapod backbone.

Stephanie Pierce explains, "By understanding how each of the bones fit together we can begin to explore the mobility of the spine and test how it may have transferred forces between the limbs during the early stages of land movement".

But, the findings didn't end there. One of the animals - known as Ichthyostega - was also found to have an assortment of hitherto unknown skeletal features including a string of bones extending down the middle of it’s chest.

Jennifer Clack says, "These chest bones turned out to be the earliest evolutionary attempt to produce a bony sternum. Such a structure would have strengthened the ribcage of Ichthyostega, permitting it to support it’s body weight on it’s chest while moving about on land."

This unexpected discovery supports recent work by Pierce and Clack that showed Ichthyostega probably moved by dragging itself across flat ground using synchronous 'crutching' motions of its front legs - much like that of a mudskipper or seal. Dr Pierce adds, “The results of this study force us to re-write the textbook on backbone evolution in the earliest limbed animals."

“At the ESRF, the new data extraction protocol makes it possible to study fossils in dense and heavy rock in unprecedented detail. What we have seen today is only the beginning of more surprises to come,” concludes Sophie Sanchez.

Stephanie E Pierce, Per E Ahlberg, John R Hutchinson, Julia L Molna, Sophie Sanchez, Paul Tafforeau, and Jennifer A Clack. Vertebral architecture in the earliest stem tetrapods. Nature, 13 January 2013 DOI: 10.1038/nature11825

Limb Regeneration in Tadpoles

Tadpoles. Photo Credit: Manchester University.

It is generally appreciated that frogs and salamanders have remarkable regenerative capacities, in contrast to mammals, including humans. For example, if a tadpole loses its tail a new one will regenerate within a week. For several years Professor Enrique Amaya and his team at The Healing Foundation Centre in the Faculty of Life Sciences have been trying to better understand the regeneration process, in the hope of eventually using this information to find new therapies that will improve the ability of humans to heal and regenerate better.

In an earlier study, Professor Amaya’s group identified which genes were activated during tail regeneration. Unexpectedly, that study showed that several genes that are involved in metabolism are activated, in particular those that are linked to the production of reactive oxygen species (ROS) - chemically reactive molecules containing oxygen. What was unusual about those findings is that ROS are commonly believed to be harmful to cells.

Professor Amaya and his group decided to follow up on this unexpected result and their new findings will be published in the next issue of Nature Cell Biology.

To examine ROS during tail regeneration, they measured the level of H2O2 (hydrogen peroxide, a common reactive oxygen species in cells) using a fluorescent molecule that changes light emission properties in the presence of H2O2. Using this advanced form of imaging, Professor Amaya and his group were able to show that a marked increase in H2O2 occurs following tail amputation and interestingly, they showed that the H2O2 levels remained elevated during the entire tail regeneration process, which lasts several days.

Talking about the research Professor Amaya says: “We were very surprised to find these high levels of ROS during tail regeneration. Traditionally, ROS have been thought to have a negative impact on cells. But in this case they seemed to be having a positive impact on tail re-growth.”

To assess how vital the presence of ROS are in the regeneration process, Professor Amaya’s team limited ROS production using two methods. The first was by using chemicals, including an antioxidant, and the second was by removing a gene responsible for ROS production. In both cases the regeneration process was inhibited and the tadpole tail did not grow back.

Professor Amaya says: "When we decreased ROS levels, tissue growth and regeneration failed to occur. Our research suggests that ROS are essential to initiate and sustain the regeneration response. We also found that ROS production is essential to activate Wnt signalling, which has been implicated in essentially every studied regeneration system, including those found in humans. It was also striking that our study showed that antioxidants had such a negative impact on tissue regrowth, as we are often told that antioxidants should be beneficial to health."

The publication of Professor Amaya's study comes just days after a paper from the Nobel Prize winner and co-discoverer of the structure of DNA, James Watson, suggested antioxidants could be harmful to people in the later stages of cancer.

Professor Amaya comments: "It's very interesting that two papers suggesting that antioxidants may not always be beneficial have been published recently. Our findings and those of others are leading to a reversal in our thinking about the relative beneficial versus harmful effects that oxidants and antioxidants may have on human health, and indeed that oxidants, such as ROS, may play some important beneficial roles in healing and regeneration."

The next step for the team at the Healing Foundation Centre will be to study ROS and their role in the healing and regenerative processes more closely. With a better understanding, Professor Amaya and his team hope to apply their findings to human health to identify whether manipulating ROS levels in the body could improve our ability to heal and regenerate tissues better. Thus these findings have very important implications in regenerative medicine.
Nick R. Love, Yaoyao Chen, Shoko Ishibashi, Paraskevi Kritsiligkou, Robert Lea, Yvette Koh, Jennifer L. Gallop, Karel Dorey, Enrique Amaya. Amputation-induced reactive oxygen species are required for successful Xenopus tadpole tail regeneration. Nature Cell Biology, 2013; DOI: 10.1038/ncb2659

Friday, January 11, 2013

Suizo Report -- Speedbump and Gus

Howdy Herpers,                                                                               10 January 2013

As I'm sure none of you remember, back in January of 2010 I sent out some images of a desert tortoise with some carapace damage--as if it had been run over by an ATV or other vehicle. I have been faithfully visiting its burrow ever since. It did not appear to return in 2011 or 2012.

That is, it was not there during my visits. I'm pleased to announce that on 8 January of this year, it was back.

It is amazing how this resilient tortoise survived what had to be major trauma. I have attached images from 2010, and 2013.

Also amazing is one of our Black-tailed Rattlesnakes, CM11, "Gus." He has been visible with every visit this winter, and completely out basking on 6 January (See image 3). While this behavior could be a bad sign, I somehow believe that Gus is like one of those studs that you see in the stands at football game with his shirt off in cold weather. Time will tell. For now, I'm going to keep my thoughts righteous and pure, and presume that all is well with Gus.

Everything else is sitting tight out in paradise. We're about to experience some VERY cold weather this weekend. It will be interesting to see what Gus does in extreme cold.

Image 1: Speedbump, January 2010

Image 2: Speedbump, January 2013

Image 3: The mighty Gus, 6 January, 2013
Best to all, roger

Wednesday, January 9, 2013

Rat Snakes & Global Warming

URBANA – Speculation about how animals will respond to climate change due to global warming led University of Illinois researcher Patrick Weatherhead and his students to conduct a study of ratsnakes at three different latitudes—Ontario, Illinois, and Texas. His findings suggest that ratsnakes will be able to adapt to the higher temperatures by becoming more active at night.

“Ratsnakes are a species with a broad geographic range so we could use latitude as a surrogate for climate change,” Weatherhead said. “What are ratsnakes in Illinois going to be dealing with given the projections for how much warmer it will be 50 years from now? Well, go to Texas and find out. That’s what they’re dealing with now. Snakes are ectotherms, that is, they use the environment to regulate their body temperature. We were able to compare ratsnakes’ ability to regulate their temperature in Texas as compared to Illinois and Canada.”

The research showed that ratsnakes in Canada, Illinois, and Texas would all benefit from global warming. “It would actually make the environment thermally better for them,” Weatherhead said. “Texas is already too hot for much of the day so it may cause them to shift to even more nocturnal foraging there and stay active at night for more of the season.”

As the higher temperatures associated with global warming begin to be more challenging for snakes in Illinois, will they be able to switch to nocturnal foraging? “We think that won’t be a problem for them,” Weatherhead said. “We already know that Illinois snakes show some limited amount of nocturnal activity because there is anecdotal evidence for nocturnal nest predation by snakes.”

Weatherhead said that as temperatures increase there are a lot of potential scenarios of what might happen in the ecosystem.

“If we start with the premise that with a thermal increase snakes will do better, the snake population may increase, but snakes are also facing diminished habitat and have a high road mortality. They are not a universally well-loved group of animals. People are known to purposely swerve in the road to kill them. So, just because temperatures may become more beneficial for snakes it doesn’t necessarily mean we’ll have a plague of snakes. We may, however, have northern expansion of ranges,” he said.

Weatherhead inserted tiny transmitters that emit radio pulses into ratsnakes to track their location and behavior. In order to save battery life through the winter months while the snake was hibernating, the transmitters were designed to slow its pulse rate (not the pulse rate of the snake) as the temperature dropped. “The relationship between the change in temperature and how it affects the transistor’s pulse rate is pretty precise.  We learned that we could predict the temperature of the snake from the pulse rate of the transmitter,” he said.

Weatherhead’s team also created snake models using a piece of copper pipe filled with water and painted black with a transmitter inside it. They placed the simulated snakes in various microhabitats--under a log, up in a tree, and on bare ground. This provided representative samples of all of the places that are available to a real snake while exposed to a range of weather conditions.

“We got the weather data from standard weather stations, then developed predictive equations from the weather conditions and the model snake’s body temperature under each condition,” Weatherhead said. “After you’ve sampled the environment once, then it’s just the physical relationship between those environmental factors and the inanimate snake model which very closely mimics a real snake in those same circumstances.  You plug the weather data into these equations and you can tell what temperature a snake in each of those environments would be at any time,” he said.

Weatherhead said that although temperature-sensitive transmitters have been available for some time, automated receivers vastly increased data collection. The research approach used now combines automated temperature recording with automated recording of snakes’ locations.

Weatherhead said the environmental domino effect could mean a reduction in some native bird populations because the snakes he studies are important predators of birds’ nests. During the night, in addition to eggs and young birds in nests, adult females may also get caught unawares.

“Females are often on the nest incubating eggs or brooding the young at night,” Weatherhead said. “If they are doing that during the day and a snake approaches, they rarely get caught by the snake, but at night they are much more vulnerable because snakes are very stealthy and the incubating birds don’t detect the snake approaching. This is good for the snake because it gets a bigger meal.

“The environmental repercussions could be significant if you start eliminating adult females from a population, particularly an endangered species,” he said. “The loss of females for native birds will have a big demographic effect on bird populations.”

Weatherhead is currently conducting another study in South Carolina comparing a species of snake that appears to only forage during the day with one that can switch to nocturnal foraging to understand more about the relationship between prey, predators and climate.

“We’re looking at the whole community of nesting birds that the snakes prey on,” he said. “We have cameras aimed at hundreds of nests to determine who the predators are, when the predation happens, and what the fate of the nest is both for the nest contents and the parent birds.”

Weatherhead explained that snakes can find nests in the dark because they don’t rely on vision alone to find birds’ nests.

“Snakes have a really good sense of smell,” he said. “We’ve done lab experiments in which we give snakes three choices under darker conditions. They can choose to go into a tube that leads to a dead mouse, a simulated live mouse, or both. They do better when they get both under light and dark conditions, so it looks as if they are fairly flexible regarding which sensory mechanism that they are using to find prey.”

The primary predators of ratsnakes are hawks and small carnivores. “When the snake tries to get to a nest during the day, the adult bird makes a commotion and attracts hawks or other snake predators,” Weatherhead said. “A snake is a bigger meal to a hawk than a few eggs.”  If a warmer climate causes snakes to be more active at night, they may be less vulnerable to animals that hunt them, so the mink, hawk, and raccoon populations could also be adversely affected. “Predicting the ecological consequences of climate change for wildlife requires going beyond the study of single species,” he said.

Latitudinal variation in thermal ecology of North American ratsnakes and its implications for the effect of climate warming on snakes was published in a 2012 issue of the Journal of Thermal Biology. Jinelle H. Sperry, Gerardo L.F. Carfagno, and Gabriel Blouin-Demers contributed to the study. Partial funding was provided by the United States Army and the Army Corps of Engineers.

Patrick J. Weatherhead, Jinelle H. Sperry, Gerardo L.F. Carfagno, Gabriel Blouin-Demers. Latitudinal variation in thermal ecology of North American ratsnakes and its implications for the effect of climate warming on snakes. Journal of Thermal Biology, 2012; 37 (4): 273 DOI: 10.1016/j.jtherbio.2011.03.008

Sunday, January 6, 2013

Controlling Python bivittatus: the 2013 Python Challenge

The Florida Fish and Wildlife Conservation Commission and its partners (including Wildlife Foundation of Florida, The Future of Hunting in Florida, University of Florida, Zoo Miami, and The Nature Conservancy) are initiating the 2013 Python Challenge in an attempt to enlist both the general public and python permit holders in a month-long harvest of Burmese pythons. The events associated also include the general public who is invited to two free educational events .

The Python Challenge starts Jan. 12, 2013 with an event at the University of Florida Fort Lauderdale Research and Education Center in Davie, and concludes with an Awards Event will be Feb. 16, 2013 at Zoo Miami.

The goal of the 2013 Python Challenge is increasing public awareness about the Burmese python and how this invasive species is a threat to the Everglades ecosystem and its native wildlife. It is also to encourage responsible harvesting of Burmese pythons; talk about how responsible pet ownership; and encourage people to report sightings of all invasive species.

The invasion of these large exotic snakes in Florida, has received international attention.

The 2013 Python Challenge kickoff event will feature training sessions and talks about identifying Burmese pythons and other nonnative reptiles. These activities are for both the general public and the people registered or planning to register to compete in the month-long harvest of Burmese pythons in the Everglades. Additional training will be available for Python Challenge participants on safely harvesting pythons, data collection, and maps displaying the areas where the competition will take place.

In conjunction with the kickoff, the University of Florida Fort Lauderdale Research and Education Center will hold its annual open house featuring research and management efforts on a number of invasive species. The "Culinary Safari" chef will be cooking up dishes featuring exotic species. Making invasive species tasty may be the most efficient way to reduce its numbers - consider the number of species that have become threatened or endangered (or even extinct) because of market hunting.

There will be a ceremony to announce the winners of the 2013 Python Challenge. Awards will be given to the people who harvested the longest Burmese python and the most Burmese pythons in the contest's two categories: the General Competition and the Python Permit Holders Competition. The awards include a $1500 for the longest snake.

Michael Dorcas of Davidson College gave an interview to Yale Environment 360 on 12 September 2012. He provided some background on the invasive snake:
"e360: When did this start to become a problem?
Dorcas: Well, the research that we’ve done has shown that Burmese pythons have probably been a reproducing population in the Everglades at least since the 1980s. But it wasn’t until the year 2000, which is the year they were recognized as being established as a reproducing population, that the numbers started to increase dramatically and their geographic range started to increase substantially as well.
e360: How many do you think are out there now? And what kind of geographic range are we talking about?
Dorcas: It’s hard to know exactly where the front is, in terms of the invasion front, and how far north they’ve moved now. They’ve certainly moved south onto Key Largo. They’re certainly covering all of Everglades National Park, all of Big Cypress National Preserve, and are probably well north of Alligator Alley now.
"And in terms of how many, snakes are really difficult to do population estimates on because they’re so secretive. Even big snakes like this are really difficult. You combine that with the fact that you’ve got a terrain in South Florida of which a very small percentage is actually accessible to humans. And you also combine that with the fact that we really can’t do “mark-recapture” on these to determine population size or density. So we really don’t know. People guess anywhere from thousands to millions, but regardless of what people tell you, we really don’t know. But there are a lot of pythons. I would venture a guess at least tens of thousands of pythons. And we’re talking over 5,000 to 8,000 square kilometers. So we’re talking about a big geographic area."
The python harvest has come under some criticism from Scientific American blogger Kate Wong, she writes,
"How reliably can a novice sort Burmese pythons from native Florida snakes—some of which are venomous—in the wild after 30 minutes of preparation online? And obvious human safety concerns aside, can someone who has never handled snakes before really be counted on to kill a large constrictor humanely in the heat of the moment? Check out those euthanasia guidelines—they’re more complicated than you might think. 
"The Burmese python is a very real problem for Florida’s residents—humans and wildlife alike. But the 2013 Python Challenge does not seem like the wisest way to tackle it."
The analogy that immediately comes to mind is opening day of deer hunting season in Wisconsin or Michigan - how many hunters get shot by their colleagues? People who hunt are usually aware of the risks.

At least two media production companies are casting for the  Python Challenge 2013. The Matador Network and Naples-based ITZ Media Group have sent email pitches to hunters who've already signed up for the competition. Emails from both companies say they are pitching a reality show to major cable networks.

In late December a family visiting Florida from Arkansas encountered a 17-foot python while having a picnic, the snake was killed by Everglade's Park Rangers.

It will undoubtedly have a circus atmosphere, some of the participating python hunters will make a spectacle of themselves, some minor injuries can be expected. But, the downsides seem to be a small price to pay for 
controlling Python bivittatus in Florida, and slowing the damage to the Everglades ecosystem.

Saturday, January 5, 2013

A Global Assessment of Reptiles

The first global overview of reptile extinction risk has been published in the journal Biological Conservation (Böhm et al. 2013). 220 species assessed on the IUCN Red List and another 1280 species with revised or new assessments provided by a global network of herpetologists formed the basis for the study. Thus, the sample included about 16% of known reptile species. The processes forming the major threats to the species and the proportion of species threatened by each predominant threat were mapped. Three of the species were found to lack sufficient distributional data and were not included in the mapping process, leaving 1497 species represented in the maps.

The study found 59% of reptile species in the assessment as species of Least Concern, 5% as Near Threatened, 15% as threatened (Vulnerable, Endangered or Critically Endangered) and 21% as Data Deficient. Based on this, the authors estimated the true percentage of threatened reptiles in the world to be about 19-20%. Another 7% of species are estimated as Near Threatened. These are the species most likely to become threatened in the future if measures are not taken to eliminate the negative human activities which currently impact their populations. None of the species in the sample were classified as Extinct or Extinct in the Wild, although three lizard species in the Critically Endangered category were flagged as possibly extinct (Anolis roosevelti [see below] Ameiva vittata and Stenocercus haenschi) and their status may be changed pending the results of future field surveys

223 reptilian species were classed as threatened, about half of these (47%) were assigned to the Vulnerable category; another 41% and 12% were assessed as Endangered and Critically Endangered respectively. Threat estimates for terrestrial species mirrored that recorded for all reptiles (19% threatened) because the vast majority of reptiles inhabit terrestrial environments. However 30% of reptiles associated with marine and freshwater environments are estimated to be threatened. Reptile species diversity is greatest in tropical latitudes, Central America, portions of South America, tropical West Africa, south Africa, Sri Lanka, southern India, and Southeast Asia eastward to the Philippines have the highest proportions of threatened species. Species classified as Data Deficient were in Inodomalaysia (33%), the Neotropics (20%), and the Afrotropics (18%).

Of the 24 known species of crocodilians, four species were assessed, and three of the four are threatened. Of the 323 known species of turtle, 46 were assessed and 51% of these were threatened. Snakes and lizards (including amphisbaenids) appear to be in better shape with 28% and 12% of those assessed considered threatened.

For comparison to other higher vertebrate groups, 25% of freshwater fishes, 42% of amphibians, 13% of birds, and 25% of mammals are considered threatened. Thus, the 20% of threatened reptiles would appear to be a moderate number.

But, reptiles are under studied, there is a large number of undescribed species (more than 153 new species were described in 2012 alone, an increase of almost 2%) and this study notes that 21% are classified as Data Deficient.

The composite above shows the Culebra Island Giant anole, Anolis roosevelti. One species of reptiles than may be extinct in the wild. The male holotype was described in 1931 by Chapman Grant. It had a body length of 160 millimeters  It was observed again in 1932  and there have been unconfirmed sightings since 1973 . Some speculate it may still exist, others are less optimistic. Its preferred  habitat was gumbo-limbo and ficus trees and it fed on the fruits of the trees. Human activities destroyed most of its habitat. Photo and artist credit:  A. Photo by Chapman Grant, B. Photo by Leo Shapiro. C. Artists reconstruction by Genny Wilson.

Böhm, M. et al. 2013. The conservation status of the world's reptiles. Biological Conservation 157, 372-385.

Feathers and Courting Dinosaurs

Above: Artist's conception of the feathered dinosaur Similicaudipteryx using its tail feathers in a mating display. (Illustration: Sydney Mohr)

A University of Alberta researcher’s examination of fossilized dinosaur tail bones has led to a breakthrough finding: some feathered dinosaurs used tail plumage to attract mates, much like modern-day peacocks and turkeys.

U of A paleontology researcher Scott Persons followed a chain of fossil evidence that started with a peculiar fusing together of vertebrae at the tip of the tail of four different species of dinosaurs, some separated in time and evolution by 45 million years.

Persons says the final vertebrae in the tails of a group of dinosaurs called oviraptors were fused together, forming a ridged, blade-like structure. “The structure is called a pygostyle” says Persons. “Among modern animals, only birds have them.”

Researchers say fossils of Similicaudipteryx, an early oviraptor, reveal feathers radiating from the fused bones at the tail tip. Similicaudipteryx was not known to be a flying dinosaur, and Persons contends its tail feathers evolved as a means of waving its feathered tail fans.

No direct fossil evidence of feathers has been found with the fossils of the oviraptors that followed Similicaudipteryx, but Persons says there is still strong evidence they had a feathered tail.

Persons reasons that because the later oviraptor had the same tail structure as the feathered Similicaudipteryx, the tails of later oviraptors still served the same purpose.

He says the hypothesis of oviraptor tail-waving is supported by both the bone and muscle structure of the tail.

Individual vertebrae at the base of an oviraptor’s tail were short and numerous, indicating great flexibility. Based on dissections of modern reptile and bird tails, Persons’ reconstruction of the dinosaur’s tail muscles revealed oviraptors had what it took to really shake their tail feathers.

Large muscles extended far down the tail and had a sufficient number of broad connection points to the vertebrae to propel oviraptors’ tail feathers vigorously from side to side and up and down.

Oviraptors were two-legged dinosaurs that had already gone through major diversifications from the iconic, meat-eating dinosaur family. Oviraptors were plant-eaters that roamed parts of China, Mongolia and Alberta during the Cretaceous period, the final age of the dinosaur.

“By this time, a variety of dinosaurs used feathers for flight and insulation from the cold,” said Persons. “This shows that by the late Cretaceous, dinosaurs were doing everything with feathers that modern birds do now,” said Persons.

In addition to feathered-tail waving, oviraptors also had prominent bone crests on their head, which Persons says the dinosaurs also may have used in mating displays.

“Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism,” said

W. S. Persons, IV, P J. Currie, and M.A. Norell. Oviraptorosaur tail forms and functions. Acta Palaeontologica Polonica, 2013; DOI: 10.4202/app.2012.0093

Friday, January 4, 2013

The amphibian & reptile extinction crisis

Alligator Snapping Turtle
The following is from the Center for Biological Diversity.

Amphibians and reptiles are amazing creatures with clever adaptations that have allowed them to brave the millennia. Consider the Coachella Valley fringe-toed lizard’s scaly hind toes, which resemble snowshoes and keep the lizard from sinking into sand as it sprints away from predators; or the eastern diamondback rattlesnake’s heat-sensing pit organ, which helps it find the small, warm-blooded prey on which it feeds. Such diversity is vital to functioning ecosystems and enriches humankind’s enjoyment of the natural world.

See the CBD's website for a full-sized U.S. map to see which of our petitioned-for amphibians and reptiles live in your state — plus their full ranges.

But today, the world’s herpetofauna are among the most imperiled species on Earth. Ubiquitous toxins, global warming, nonnative predators, overcollection, habitat destruction and disease are key factors leading to their demise. Globally, 664 species of reptiles, or more than 20 percent of the total evaluated species, are endangered or vulnerable to extinction, according to the International Union for Conservation of Nature’s 2011 Red List. The situation is worse for amphibians. More than 1,900 species of frogs, toads and salamanders — fully 30 percent of the world’s amphibians — are at risk of dying out. Moreover, scientists lack sufficient information to assess the status of nearly 25 percent of the world’s herps. These species are slipping away faster than scientists can study them.

The Center outdid ourselves in protecting these amazing creatures on July 11, 2012, when we made the biggest-ever move to protect amphibians and reptiles in the United States, filing a mega-petition requesting Endangered Species Action protection for 53 amphibians and reptiles in 45 states. The petition, filed with E.O. Wilson, Thomas Lovejoy and others, asks the U.S. Fish and Wildlife Service to protect six turtles, seven snakes, two toads, four frogs, 10 lizards and 24 salamanders under the Act.

To learn more about amphibians and reptiles, read our FAQ and then sign up for future alerts about how you can help save species.

Almost since its inception, the Center has worked to protect reptiles and amphibians. By filing petitions that urge federal wildlife agencies to provide Endangered Species Act protection for imperiled herps — and following up with lawsuits when necessary — the Center has obtained federal safeguards and critical habitat for dozens of amphibians and reptiles, from the Chiricahua leopard frog to the Mississippi gopher frog to the Tucson shovel-nosed snake.

In July 2012, the Center, E.O. Wilson, Thomas Lovejoy and others petitioned to protect 53 of the nation’s most imperiled amphibians and reptiles under the Endangered Species Act. In September of that year, More than 200 scientists sent a letter to the U.S. Fish and Wildlife Service expressing support for our petition.

Stemming the herpetofauna extinction crisis means attacking it on every front; the Center’s conservation efforts are almost as diverse as the animals we’re working to protect. To reduce impacts of toxic pesticides on the California red-legged frog, the Center secured a settlement with the U.S. Environmental Protection Agency that prohibits the use of 66 toxic pesticides near core habitats. And a follow-up lawsuit against the U.S. Fish and Wildlife Service seeks permanent restrictions on these deadly toxins. The Center’s campaign for fish-stocking reform aims to protect the Sierra Nevada yellow-legged frog and other amphibians from nonnative trout, while litigation against the Forest Service has helped curb grazing-driven habitat destruction for the Oregon spotted frog.

While threats like our warming climate require efforts across the globe, threats like human persecution can be addressed by working at the level of communities or regions. For example, the eastern diamondback rattlesnake is facing population declines due in part to “rattlesnake roundups,” which are contests calling for hunters to collect (and later kill) as many snakes as they can in a year. Through our campaign to outlaw rattlesnake roundups, the Center aims to convince local communities to turn these gruesome contests into wildlife appreciation festivals. Freshwater turtles are also being threatened by human persecution, namely by overcollection for the food and the pet trade. Our successful ongoing campaign on behalf of southern and midwestern turtles has prompted several states to regulate turtle harvest, an important step toward reversing their alarming declines.

Though amphibians and reptiles represent some of the most rapidly disappearing species on Earth, they’ve long been underrepresented when it comes to wildlife protection. So in 2010, the Center made certain that animals like the California tiger salamander have their very own champion by hiring the nation’s first full-time attorney dedicated to conserving herpetofauna.

An insular, high elevation population of the semi-aquatic dice snake in Macedonia

The dice snake and its distribution.
The semi-aquatic dice snake (Natrix tessellata) ranges from Italy to China, an east-west axis of more than 5500 km and it uses a very wide variety of habitats. Current ecological information on this species is limited to the most western parts of the species’ range, notably Italy, Switzerland, and Germany. Preliminary reports from other areas  suggest that this species might be polytypic. A study in press and online in early view (Ajtic et al) investigates how its ecological situation may influence its life history adaptations.  The authors examine a very dense population of dice snakes on Golem Grad, an 18 ha  island  situated in a high altitude lake (850 m above sea level) where the species environment is quiet divergent from other study sites in Western Europe. Island life deeply influences a wide range of life history traits, particularly diet, predation, and density dependent processes. The Golem Grad population exhibits a set of unusual characteristics in this high population density, insular environment.

The authors marked more than 5000 individuals and produced estimates of more than 500 snakes per hectare, one of the highest ever recorded for snakes. Reproductive and mortality rates are elevated, suggesting a high population turnover. These traits evoke a tropical rather than a temperate-climate demographic pattern. The Golem Grad population is highly polymorphic, three color morphs (spotted, grey, and black) are observed in both sexes and each morph is represented by large numbers of individuals.  Data obtained for other life history traits ( body size, size at maturity, clutch size, diet, predation) suggest this population is quite diverged in comparison to other populations. Overall,the results reinforce the idea that the inter-population variability  of snakes should be taken into account over large geographic scales; otherwise attempts to derive general patterns may well be strongly biased.

R. Ajtića, L. Tomović, B. Sterijovskid, J. Crnobrnja-Isailović, S. Djordjević, M. Djurakić, A. Golubović, A. Simović, D. Arsovski, M. Andjelković, M. Krstić, G. Šukalo,  S. Gvozdenovićh, A. Aïdam, C. L. Michel, J-M. Ballouard, X Bonnet. 2013. Unexpected life history traits in a very dense population of dice snakes. Zoologischer Anzeiger - A Journal of Comparative Zoology

Thursday, January 3, 2013

Forest management & the salamander

Plethodon albagula. Photo credit Stanley Trauth
Lungless, woodland salamanders depend on forested habitats and are sensitive to changes in temperature and moisture associated with many forestry practices. Additionally, woodland salamanders are territorial and have relatively low vagility, making it unlikely that they can successfully migrate to more favorable habitat when the surrounding forest is harvested. Therefore, Hocking et al. (2013) examine the abundance of the western slimy salamander, Plethodon albagula, in an experimentally manipulated forest in central Missouri. They used artificial cover object searches to compare salamander abundance in three replicate treatments that were clear-cut then burned to reduce maple regeneration, clear-cut and not burned, partially harvested, and un-manipulated control forest. They captured a total of 300 Western slimy salamanders between April 2007 and September 2011. The authors found significantly fewer salamanders in the burn and clear-cut treatments compared with the partial and control treatments. We also found a lower proportion of juveniles and had fewer recaptures in the burn and clear-cut than in the partial and control treatments. Consistent with other studies of woodland salamanders, their results suggest that for at least the first 7 years post-harvest, clear-cutting is detrimental to woodland salamander populations. This initial reduction in abundance combined with the further reduced proportion of juveniles may have longer lasting effects even as the forest regenerates. Finally, the study suggests that timber harvest resulting in limited canopy thinning may be compatible with maintaining populations of Western Slimy Salamanders in Missouri.

Hocking, D. J., Connette, G. M., Conner, C. A., Scheffers, B. R., Pittman, S. E., Peterman, W. E., Semlitsch, R. D.(2013) Effects of experimental forest management on a terrestrial, woodland salamander in Missouri.  Forest Ecology and Management 287:32-37.

Two new Anomaloglossus frogs from Panama

Anomaloglossus astralogaster. Photo credit: Marcos Guerra
The Chagres Highlands may be a lower montane forest refuge for some rare amphibians and reptiles. In a recent paper,  Meyers et al, (2012)  documents the presence of the South American frog genus Anomaloglossus (Dendrobatoidea: Aromobatidae) based upon two new species from this area. The two species are described from a low, forested uplift in east central Panama, just northeast of Panama City. These low mountains, unnamed on maps, are designated the “Chagres Highlands” because a large part of the uplift lies in the Río Chagres drainage, an area that provides water critical to lock operation in the Panama Canal. The Chagres Highlands may be a lower montane forest refuge for some amphibians and reptiles, including the two Anomaloglossus as well as Atelopus limosus, and some rare snakes including: Atractus depressiocellus, A. imperfectus, Geophis bellus, and Rhadinaea sargenti. Several other rare species are not endemic but include the Chagres Highland area as part of their individually fragmented or mosaic distributions (Adinobates fulguritus, Anolis kunayalae, Coniophanes joanae, Geophis bracycephalus, Dipsas nicholsi). The two new frogs are  sympatric in the Chagres Highlands, but both species are rare. Anomaloglossus astralogaster, a new species, is known only from the adult 22 mm, female holotype. It has its ventral surfaces covered with whitish dots  somewhat similar to large chromatophores but possibly glandular; there is no appearance of glandular structure  but the edges of some of the pale dots can be “felt” with a fine  teasing needle and histological examination is needed. The other new taxon is Anomaloglossus isthminus, which is described from six specimens. Its dorsal surfaces are basically brown mottled with darker brown. Small pale yellowish spots located proximally above the insertions of arm and thigh are not well defined and tend to disappear after preservation (unlike normal dendrobatid flash markings). Ventral surfaces are pale blue with some dark mottling but no pale dots. The vocalization of A. isthminus resembles calls of some South American species in being a train of “peeplike” notes, but there are fundamental interspecific differences in frequency modulation, note repetition rate, and call length.

The new  Anomaloglossus are known only from the Chagres Highlands in east-central Panama, but it cannot be safely concluded that they are endemic to this area. The best known part of these highlands is the Piedras-Pacora Ridge on the continental divide,  which has been suggested as a “premontane forest refuge for some small part of the fauna that is barely surviving the climatic-vegetational changes of the Pleistocene. It is conceivable  that Anomaloglossus occurs more widely in Panama, possibly, in fragmented pockets along the broken Serranía de San Blas and northern part of the Serranía del Darién, where collecting has been very sporadic.

Myers, C. W.; Ibañez D., R.; Grant, T., Jaramillo A., César A. 2012. Discovery of the frog genus Anomaloglossus in Panama, with descriptions of two new species from the Chagres Highlands (Dendrobatoidea, Aromobatidae).American Museum of Natural History, 3763, 1-19.