Friday, September 3, 2010

Diet of an Ancient Snake

The Amazonian Pipe Snake, Anilus scytale. JCM

The Amazonian Pipe Snake, Anilius scytale, represents a poorly known, ancient lineage of snakes. They are a basal alethinophidian and lack the ability to open their mouth widely. Previous work suggested they feed on elongated amphibians and reptiles. Maschio et al. (2010) examined 162 specimens from the Brazilian Amazonia for food items, only 12% contained prey.  Three species of amphisbaenians (Aulura anomala, Leposternon polystegumn, and Amphisbaena sp.), accounted for 81% of the diet items recovered. The remainder were snakes (Anilius scytale and Tantilla melanocephala) making up 12.5% and caecilians (Caecilia cf. gracilis) composing another 6.25%. They found a positive (but not significant) relationship between the snout-vent length of the pipe snakes and the total length of their prey, with a tendency for smaller specimens to ingest proportionately larger prey. Based upon the prey found, Anilius forages mostly on the ground and in aquatic environments at night. Prey was ingested headfirst, and is likely to minimize the risk of injury. Full citation: Maschio, G. F.,  A. LĂșcia da C. Prudente, F. da S. Rodrigues and M. S. Hoogmoed 2010. Food habits of Anilius scytale (Serpentes: Aniliidae) in the Brazilian Amazonia. Zoologia .27(2). This paper can be found on-line at: http://www.scielo.br/scielo.php?pid=S1984-46702010000200005&script=sci_arttext&tlng=en.

File Snake Phylogeny

Acrochordus javanicus. JCM

Filesnakes (Acrochordus) are unusual. They are completely aquatic, living in both fresh and salt water; they have baggy skin with rough scales containing sensory organs; and they the ability to stay underwater for long periods of time. Additionally, they have an Indo-Australian distribution. Three living species are recognized and a fourth species (A. dehmi) is known only from its fossilized vertebrae from Pakistan. One of these, the Elephant Trunk Snake (A. javanicus), is heavily hunted for its skin and meat.  Now, Sanders et al. have estimated divergence times for these snakes and looked at their phylogeny using morphology, fossils, and DNA. Their results show that A. javanicus (a South and Southeastern Asian endemic) is the sister to the Arafura Filesnake (A. arafurae) an Australasian endemic and the widespread, marine Little File Snake (A. granulatus). The divergence of the three extant species was dated at 20.3 MYA (million years ago) and A. granulatus diverged from A. arafurae 15.6 MYA. Their molecular data support the Acrochordids and Colubroidae as sister groups that separated about 62 MYA. Full citation: Sanders, K. L., Mumpuni, A. Hamidy, J. J. Head, and D. J. Gower. 2010. Phylogeny and divergence times of filesnakes (Acrochordus): inferences from morphology, fossils, and three molecular loci. Molecular Phylogenetics and Evolution 56:837-867.

Thursday, September 2, 2010

Lizard SVLs & Weights

Hatchling Anolis sagrei.

Shai Meiri of Tel Aviv University's Department of Zoology has developed a method for translating lizard body lengths to weights. Meiri's new equations calculate this valuable morphological feature to estimate the weight of a lizard species in a variety of different ecosystems.Lizards are frequently important indicator species for understanding the condition of specific ecosystems. Their body weight is a crucial index for evaluating species health, but lizards are seldom weighed, perhaps due in part to the recurring problem of spontaneous tail loss when lizards are in stress. Meir has generate equations to estimate weights from the snout–vent length.And, he used a species-level phylogenetic hypothesis to examine the ecological factors that affect the variation in weight–length relationships. Limbless and reduced limbed lizards are characterized by shallower allometric slopes, and thus long-bodied, legless species are lighter than legged lizards of comparable length. In limbed species the foraging strategy strongly influences the weights, with ambush species being bulkier at comparable lengths than active foraging species. In this study 900 species in 28 different families were used to generated a dataset of lizard weights. Full Citation: Meiri, S. 2010. Length–weight allometries in lizards. Journal of Zoology 281(3):218–226.

Burmese Python Found in Indiana



WXIN, Fox Channel 59 is reporting that an 11 foot Burmese Python was found in Wildcat Creek,in Tippecanoe County, Indiana. The snake was caught by three fishermen. September 1, 2010.

Asian Snakes Playing Dead

A Western Hognose Snake (Heterodon nasicus) displaying 
death feigning behavior. This is a North American snake, I do
not have any photos of Asian snakes death feigning.

Death feigning behavior is known in a number of different snake lineages as well as other groups of vertebrates. It is generally believed to confuse predators so that they abandon the prey. However, another hypothesis suggests that in snakes it is a behavior triggered by the stress of the encounter with the predator. Death feigning may have many different behavioral elements, or just a few. Snake species that feed on toads often have enlarged adrenal glands, and may produce more epinephrine during an encounter with a predator - this in turn may lead to a physiological reaction that result in death feigning. Gernot Vogel and Hans Han-Yuen now report death-feigning behavior in three species of Asian colubrids: Coelognathus radiatus, Macrocalamus chanardi, and Xenochrophis piscator. The authors note that death feigning is known almost exclusively from snakes in the Nearctic, and that the behavior has been reported from only a relatively few snakes in other regions of the world. My view of this is that Nearctic snakes are better studied, there are more herpetologists active in the Nearctic and agree with the authors that many more species will be found to display this behavior.

Monday, August 30, 2010

Titanoboa Exhibit at IU

BLOOMINGTON, Ind. -- Titanoboa cerrejonensis is now a special exhibit at Indiana University Bloomington. A cast of the remains of the giant boid snake can be viewed Geology Building at 1001 E. 10th St., Bloomington, Indiana, and can be visited from 8AM to 6PM Monday through Friday. Titanoboa is estimated to have been 43 feet long and weigh 2500 pounds. Paleontologist David Polly was a coauthor of the 2009 paper in Nature that reported the discovery of the world's largest known snake. The exhibit was organized by Donald Hattin (Professor Emeritus of Geological Sciences ) and is sponsored by the IU Bloomington Geological Sciences Department and the Indiana Geological Survey. The Titanoboa exhibit will be viewable until Oct. 1, 2010. Polly will give a talk entitled Hip-deep in giant snakes: Titanoboa and temperature in the Paleocene, at 4:00 p.m. on Sept. 13 (Geology Bldg. 143). The lecture is free and open to the public.

Sunday, August 29, 2010

Is the Liana Snake a Specialized Bird Nest Predator?

The Liana Snake, Pseustes poecilonotus, is a widespread neotropical snake and probably an important predator on nestling birds. Recently I observed this species emerge from its hiding place under a corrugated tin roof at the Asa Wright Nature Center (AWNC) in Trinidad in the late afternoon. The snake was very cautious and protruded its head from under the roof for about 10 minutes before slowly crawling onto the roof's surface. The AWNC is a popular destination for bird watchers and the roof was adjacent to a large veranda surrounded by bird feeders. There were several Palm Tanager nests within three meters of the snake's hiding place. The Psuestes crawled along the roof and into a small tree where I lost track of it.  Robinson et al. [2005 Ornitologia Neotropical 16:187-195] videotaped 10 instances of nest predation on Panama's Barro Colorado Island, and P. poecilonotus was responsible for eight of the predation events. In one instance the snake ate one nestling and returned to the nest the next day and ate the second bird. Tarwater [2008, The Wilson Bulletin of Ornithology 120(3):620-624] videotaped a P. poecilonotus feeding on a nestling Western Slaty Antshrike, Thamnophilus atrinucha, on Barro Colorado Island. The snake took two minutes to consume the bird. P. poecilonotus is also known to feed on lizards and mammals, but it may specialize in nestling birds when they are available.

Tiny Frogs, and a New One from Borneo

Indraneil Das and Alexander Haas have described what has been reported as the world's smallest known frog, Microhyla nepenthicola (Family Microhylidae), in a recent issue of Zootaxa. The frog inhabits Gunung Serapi mountain, located in Kubah National Park, on the island of Borneo. Adult male M. nepenthicola are 10.6 to 12.8 mm and live in the pitcher plant Nepenthes ampullaria,  which has a globe-like pitcher and grows in damp, shady forests.  Females deposit their eggs on the sides of the pitcher, and tadpoles  grow in the water that has collected inside the plant. [Full citation: Das, I. and A. Haas. 2010. New species of Microhyla  from Sarawak: Old World’s smallest frogs crawl out of miniature pitcher  plants on Borneo (Amphibia: Anura: Microhylidae). Zootaxa, 2571 37-52.]

Tiny frog species have been discovered in abundance in recent decades and media reports claiming title to the world's smallest frog have been almost as numerous. The Brazilian Gold Frog, Brachycephalus didactylus (Izecksohn, 1971)(Family Brachycephalidae) grows to a tiny 9.8 mm and appears to still hold the title to the World's smallest frog. But there are many runners-up. Hoogmoed and Lescure described Adelophryne adiastola (Family Eleutherodactylidae) from Letica, Colombia in 1984, it has a body length of 12.9 mm. In 1986, Lynch descibed Nobella (Phyllonastes) heyeri (Family Strabomantidae) from Loja province Ecuador, males were 12.9 to 14.1 mm and females were 13.1 to 15.9 in body length. In the same paper Lynch described Phrynopus bagrecito (Family Strabomantidae)  from Cuzco, Peru; this species has males that are 13.8 to 16.3 mm and  females that are 14.4 to 18.6 mm long. The small  Monte Iberia Eleuth, Eleutherodactylus iberia, Family Eleutherodactylidae), was described from Cuba in 1996 by Estrada and  Hedges; fully grown adult males are 10.5 mm and females are 9.8 mm; it seems to most closely rival Brachycephalus didactylus for the smallest body size in frogs. Nyctibatrachus minimus (Family Nyctibatrachidae) was described by  Biju et al. in 2007 from southern India; its males average 12.3  mm in body length. Lehr and Coloma (2008) described Pristimantis andinognomus (Family Strabomantidae) . They found a maximum snout–vent length of 17.9 mm  with males averaging 12.3 mm and females averaging 15.9 mm. Lehr and Catenazzi (2009) described Noblella pygmaea (Family Strabomantidae), commonly called Noble's Pygmy Frog; females measured less than half an inch (12.5 mm) in body length, whereas males are just a bit longer than 1 cm. More recently,Teran-Valdez and Guayasamin (2010) described Pristimantis minimus from Ecuador with a maximum body length of 13.7 mm.  Below is a group of photos of some of these tiny frogs taken from a variety of sources on the web. Being small allows these species to exploit resources unavailable to larger frogs. JCM

Ellsemere Island Eocene Climate & Giant Reptiles

Ellesmere Island is adjacent to Greenalnd and covered with ice and permafrost today, but in the past it contained lush vegetation and some large reptiles. Jaelyn Eberle from the University of Colorado and colleagues have examined oxygen isotope ratios from Ellesmere fossil vertebrates that were 52 to 53 MY old and concluded that the warmest months on Ellesmere during the early Eocene averaged 66 to 68 degrees F (19-20 degrees C) and the coldest months averaged 32 to 38 degrees F (0-3.5 degrees F). Therefore it probably did not freeze, or freezing was not frequent.The island is known to have supported populations of giant tortoises and crocodilians as well as a variety of large mammals. Today there is concern that the Ellesmere fossil beds are threatened by coal mining. [Full Citation: Eberle et al. Seasonal variability in Arctic temperatures during early Eocene time. Earth and Planetary Science Letters, 2010; 296 (3-4): 481 DOI: 10.1016/j.epsl.2010.06.005]

Saturday, August 28, 2010

UK Medics Mis-Diagnosis Snake Bite Twice

A 54 year old woman was bitten by  the Adder, Vipera berus, in her garden in Eastleigh. Her ankle swelled, her leg was painful, and she suffered severe headaches. She went to Eastleigh Health Center where the doctor gave her antibiotics and assured her it was not a snakebite.The following day she was still in pain and went to Royal Hampshire County Hospital where the doctors dismissed the claim that she was bitten by a snake.The woman contacted Grange Reptiles and was told by an employee who had been a former paramedic that it was indeed a snakebite. She was admitted to Southampton General Hospital. Hampshire Chronicle, 28 August 2010. Apparently snakebite is rare enough in the UK that medical personnel have not been trained to deal with it. The same is probably true in much of the US.

Indigo Snake Conservation Effort

Project Orianne is an Indigo Snake conservation initiative that works to conserve and restore eastern indigo snake populations as well as other species of rare reptiles including Chinese Alligators, Montane Vipers, and Tortoises. The Orlando Sentinel (August 26, 2010) reports that the Lake County commissioners approved a change in zoning that will allow Project Orianne to use a 25 acre plot to culture snakes, despite a complaint form a neighbor. Fred Antonio, former curator of the Central Florida Zoo will be director of the project. JCM

Friday, July 23, 2010

Two Notes on the Reproduction of P. molurus

Two articles published in Reptile Rap, The Newsletter of the South Asian Reptile Network,  No. 10, June 2010 describe aspects of Python molurus reproduction.

Ramesh, C. and S. Bhupathy. 2010. A report on the unusual body weight of a hatchling Python molurus molurus. Reptile Rap (10):22-23.

This article describes a mean body weight of 111.2 g for a clutch of eggs laid in Keoladeo National National Park. However, one hatchling found dead near the nest weighed 200 g and showed no signs of deformity. Upon dissection the hatchling was found to have a mass of fat along the gut that may have disrupted normal body functions.

Balakrishnam, P. et al. 2010. Artificial incubation, hatching and release of the Indian Rock Python Python molurus (Linneaus, 1758), in Nilambur, Kerala. Reptile Rap (10):24-27.

Balakrishnam et al. used an environment chamber to incubate a batch of P. molurus eggs that were abandoned by the female due to human disturbance. The clutch of 17 eggs were kept between 28-32C and a relative humidity of 70-90%. Only one of the eggs hatched, the other eggs were opened and found to contain well developed embryos. The authors report that a large number of pythons are caught in lowland Nilambur and are translocated by the Forestry Department, a significant number of females snakes are killed and their eggs are left. A regional education program is in place to help protect snakes.

Wednesday, July 21, 2010

Florida Burmese Pythons are Regulating Egg Temperatures

The first report of a female Burmese Python using shivering thermogenesis in the wild has been described by Snow et al. (2010). The researchers placed data loggers in and around the brooding female python and found the female snake both warmed and cooled her eggs by generating body heat and cooling them through insulation.

Snow, R. W. et al. 2010. Thermoregulation by a brooding Burmese Python (Python molurus bivittaus) in Florida. Southeastern Naturalist 9(2):403-405.

Tuesday, June 8, 2010

Acetaminophen Toxic to Burmese Pythons and Nile Monitors

In the search to find a method to control large invasive reptiles Richard Mauldin and Peter Savarie of the United States Department of Agriculture tested acetaminophen as a potential poison to control the juveniles of alien Burmese Pythons and Nile Monitor Lizards. The pain killer was previously found to be toxic to Brown Treesnakes (Boiga irregularis) when it was administered orally. Does of 10, 20, and 40 mg resulted in mortality rates between 50 and 100%, while doses of 20, 40, and 80 mg resulted in mortality rates of 14.3, 85.7, and 100% respectively. The doses were administered by allowing the reptiles to swallow a dead neonatal mouse that contained a dose of acetaminophen. The implication is that feral reptiles could be attracted to bait that contained the toxin.

Citation: Mauldin, R. E. and P. J. Savarie. 2010. Acetaminophen as an oral toxicant for Nile monitor lizards (Varanus niloticus) and Burmese pythons (Python molurus bivittatus). Wildlife Research 37:215-222.

Saturday, June 5, 2010

Burmese Python Distribution in China Re-examined

Dave and Tracy Barker have published an updated summary of the distribution of bivittatus in China. They examine the distribution by province and analyze the known records for each. The most eastern record occurs at Naping in Fujian Province. It has also been recently reported from The Kimmen Archipelago on Queymoy Island. They found no records of the species in Guangxi, but note it is widely reported in the literature to be present. One record of a specimen from Jiangxi based on the literature appears to be based upon a visual sighting and a shed skin. P. bivittatus appears to be present in extreme southern Yunnan (on the Vietnam border) as well as extreme western Yunnan, avoiding the Shan Plateau. The authors consider the presence of bivittatus in Sichuan Province problematic. Both specimens were associated with urban areas and could represent human introduction.

Barker, D. G. and T. M. Barker. 2020. The distribution of the Burmese Python, Python bivittatus, in China. Bulletin of the Chicago Herpetological Society 45:86-88.