Saturday, June 30, 2012

2. Field Notes From Tobago

After a rather poor two weeks of collecting herps in northern Tobago, we moved to Crown Point in southern Tobago. One of the goals is to produce a list of species that use mangrove forests on Tobago. Yesterday evening was quite productive in mangroves. The list of species includes: the marine toad, Rhinella marina; the whistling frog, Leptodactylus fuscus; Garman's frog, L. validus; the house gecko, Hemidactylus mabuya; Richard's anole, Anolis richardii; and Ruschenberger's tree boa, Corallus ruschenbergeri. Most disturbing was a large butchered green sea turtle with only a maggot covered carapace remaining. This is the week of fishermen's festivals in T&T which are ritual celebrations of bountiful sea turtle harvests. The fishermen's fet's have now changed from slaughtering sea turtles, to music festivals. But based on what we found last night the change has only been for some; others continue to kill and sell sea turtles for meat. Poaching sea turtles appears to be under control in Trinidad, but out of control in Tobago. The demand for bush meat here is considerable and there is a strong hunting lobby that keeps the price for a hunting license and fines for violations low.
The turtle was found right at the entrance to Bon Accord Lagoon, below Mike Rutherford curator at the UWI Museum of Zoology posses next to the turtle carapace..
The turtle shell was found by its rancid odor.

Monday, June 25, 2012

Field Notes from Tobago


Some readers may have noticed an absence of activity on this blog, this is due to my field schedule for the summer and the generally poor internet connections available in Charlottville, Tobago. We have been sitting in a beach house for a week doing daytime hikes, snorkeling, and hanging out with the locals with few signs of the island’s unique herpetofauna.   Day time walks along streams and nighttime trail and stream walks have produced few frogs, lizards or snakes. During the day Ameiva atrigularis is highly visible as is the ever present Anolis richardii . An occasional glimpse of an iguana, an iguana nest, or locals hunting them is also a reminder that we are in the Neotropics. But, there has been no significant rain since we arrived a week ago.
One interesting observation on A. richardii, is that there appear to be two morphs of males: one that is exceptionally large (120 mm) and often has white head markings and another that is smaller (about 70 mm) that appears to be mature with a well-developed yellow dewlap and hemipenal bulges in the tail. In early and mid-morning these lizards are sitting on vertical surfaces such as tree trunks, stream banks and road-cuts.
The snakes have been hiding. 

Gabe caught a small Ruschenberger’s treeboa on a night walk along Frenchmen’s River and while walking the Blood Bay River yesterday we found a Liophis melanotus neosus on a gravel bar in the river. It died because it had been run over by a Ford Pickup truck that was parked 20 meters away – road kill in a river. 
And, Stevland found a nice melanistic Spilotes pullatus, just short of two meters in total length. 
Mike retrieved a greater windward skink, Copeoglossum aurlae from under the bark of a tree while looking for gastropods (evidence is accumulating that this species is quite arboreal).
Frogs have been present but usually the species associated with disturbed habitats. Leptodactylus fuscus can be heard continually along roads; Hypsiboans cepitans is also present in small choruses. The North Side Road was very productive last year but this year a landslide closed the road a short distance from Charlottville. The slump backed up water in the ditch and frogs ready to exploit any body of water have been chorusing here is good numbers. Of interest is Leptodactylus validus which have laid its eggs on the flooded road with females standing guard over their tadpoles.

During stream walks the glass frogs were calling from the canopy and Mike Rutherford managed to find one at eye level. One of the Glasgow students also found a tiny (9 mm) hylid that may be a metamorph of Trachycephalus typhonius. And of course, marine toads are ever present in streams, forests, and the local bars.

The trails above the fishing village are narrow and the terrain is steep, but within a few minutes we found several calling male Pristimantis charlottvillensis and a six millimeter frog that is probably Prisimantis urichi or P. turpinourm – Leptodactylus fuscus and L. validus are here also.

So, the rains have now started and with a little luck the frog and snake activity will pick up tonight.

An Outing With the TTFNC


On 16 June we spent an evening looking for herps with a group from the Trinidad and Tobago Field Naturalists Club and the Glasgow Zoological Expedition. The activities were restricted to the Lopinot Valley. We walked the river, searched small streams, and visited an abandoned building foundation that was flooded and contained a huge assemblage of frogs with about 10 chorusing species. Here are a few photos from the evening.







Saturday, June 16, 2012

Rediscovery of A Thought to be Extinct Toad


The problem with declaring a species extinct is that they are often not. In 2004 the IUCN listed Adenomus kandianus, a Sri Lankan bufonid, as extinct because it has not been recorded for over 100 years, and field work during the previous decade failed to find the toad.

Adenomus kandianus Günther (1872) was previously known only from two specimens in the British Museum. The species is endemic to Sri Lanka, and the original description gave the type locality as "Ceylon" (= Sri Lanka). The epithet suggests that it might have been collected in the vicinity of the city of Kandy, central Sri Lanka. The Kandy Toad was known only from the type specimen and one syntype until Mendis et al. (2012} reported its rediscovery.

Claims that small animals are extinct are always problematic given that populations may exist outside of the known range, the ability of many animals to enter stasis for long periods of time, and that often the animals are difficult to distinguish from their close relatives.

Citation
L. J. MENDIS WICKRAMASINGHE, DULAN RANGA VIDANAPATHIRANA & NETHU WICKRAMASINGHE (Sri Lanka): Back from the dead: The world’s rarest toad Adenomus kandianus rediscovered in Sri Lanka Zootaxa 3347: 63–68.

Saturday, June 9, 2012

The Enigmatic Horned Anole

The horned anole, Anolis proboscis was originally described in 1956 by Peters and Orces from mid-altitudes on the western slopes of the Andes in Pichincha, Ecuador. Now Losos et al. (2012) have rediscovered the species in the general vicinity of the type locality. These include several females, which lack the conspicuous rostral appendage seen in males. Despite rediscovery, the natural history of the horned anole remains almost completely unknown. The authors conducted an ecological and behavioral study of this species near Mindo, Ecuador and found it to be an extremely slow-moving and cryptic species that often occurs high in the trees. The rostral horn of the males aside, A. proboscis is indistinguishable from Greater Antillean anoles of the “twig” ecomorph class in morphology, ecology, and behavior. The horn is soft and highly flexible and thus unsuitable for use as a weapon in male–male combat; hence, the horn most likely serves as a signal and may be involved in mate choice or territorial displays. However, the anole was not observed in any social encounters and this idea has not been tested. Given its cryptic morphology and behavior, it is not surprising that A. proboscis is so rarely observed. It is now known from four localities around the town of Mindo, Pichincha province. The furthest localities are only 13 km away from each other and investigations of nearby areas for this species have not yielded results. Current thinking is that the species range is about 33 square kilometers and no more than 200 square kilometers at altitudes between 1200 and 1650 m above sea level. The horned anole is a montane forest specialist although it has been collected in pasture land and secondary forest. It is a cryptic, slow-moving, species of the forest canopy and it has been named for its proboscis, an appendage used in courtship. The entire artcle can be found on-line. 

Friday, June 8, 2012

Proposed Legislation to Control Python bivittatus in Florida

The following is from the Orlando Sentinel.

U.S. Rep. Alcee Hastings, D-Miramar, has introduced the Stopping Non-Native Animals from Killing Endangered Species (SNAKES) Act that sounds crazy but he insists could work: it would send specially trained dogs into the Everglades to sniff out, track down and direct hunters to the Burmese pythons and other non-native constrictor reptiles that are proliferating in the Glades.

Here’s excerpts from the release:

“The Florida Everglades, one of the world’s largest wetland systems and one of America’s most precious ecosystems, is under attack by the Burmese python and other large constrictor snakes. It is estimated to now hold tens of thousands of pythons that are devastating natural wildlife and endangered species living in the Everglades. In some instances, mammal populations are down 90 percent from just a few years ago.

“Auburn University EcoDogs, working along with federal, state, county, tribal government entities, universities, and non-profit stakeholders, recently trained dogs for a study to assess whether detection dogs were an effective tool for python management efforts. As it turned out, dog search teams can cover more distance and have a higher accuracy rate in particular scenarios than human searchers. The SNAKES Act authorizes the Secretary of the Interior to work with stakeholders to establish this detection program full-time. 
“Once the dog indicates that a snake is in the area, it is taken a safe distance away while a human handler captures the snake. This way, the dogs never approach the snakes and are never placed in a position of danger. This dog detection team is a great tool that can help prevent what has happened in the Everglades from happening elsewhere in the United States, as well as assist in containing the snakes populations that are already out there. I urge my colleagues in Congress to support this legislation, and help to protect and restore one of the most unique natural ecosystems.”

Wednesday, June 6, 2012

MORE RATTLERS BITING; IS VENOM MORE TOXIC?

The following is from the U-T San Diego News

More San Diegans are being bitten by rattlesnakes, and the venom seems to be getting more toxic, health officials say.

“While San Diego County is seeing a rise in snake bite cases each year, the more alarming factor is the toxicity of the bite,” Dr. Richard Clark, director of the Division of Medical Toxicology at UC San Diego Health System, said Monday.

“We don’t know for sure that the rattlesnake venom is more toxic, but it appears that way because the symptoms and the wounds we’re seeing are worse than in the past,” said Clark, who also is medical director for the San Diego office of the California Poison Control System.

Last year, 40 people in the county were treated for rattlesnake bites, according to the county Emergency Medical Services, compared with 30 people in 2010, 27 people in 2009 and 24 people in 2008.

And the numbers have jumped this year, with 15 people treated for rattlesnake bites in the first four months of 2012, including 10 people just in April, county records show. For the same period in 2011, four people were bitten.

Clark said he wasn’t surprised that the number jumped in April, when warm weather draws out both snakes and hikers to the county’s backcountry. And while toxin levels in the venom typically are stronger during the summer when snakes are active, no one knows why it may be getting more potent.

“Some speculate that with the modern world encroaching on nature, it could be survival of the fittest. Perhaps only the strongest, most venomous snakes survive,” Clark said.

“A snake’s venom also changes depending on what it’s eating and the temperature of the day. That makes every bite difficult to predict.”

While about a quarter of bites may be “dry” or not contain venom, a venomous bite can be serious or deadly. Symptoms of severe bites, which are always painful, usually start quickly and can include nausea, blurred vision, and then swelling in the mouth and throat that can make breathing difficult. Within minutes, victims can get lightheaded, collapse and go into shock.

“For anyone who suspects a bite, their next move should be to a hospital emergency department,” Clark said.

Patients are given a series of antivenin shots, which cost about $2,500 per vial, and remain hospitalized until they’re stabilized, he said.

The Weight of Giraffatitan brancai

Giraffatitan brancai
Scientists have developed a new technique to accurately measure the weight and size of dinosaurs and discovered they are not as heavy as previously thought.

University of Manchester biologists used lasers to measure the minimum amount of skin required to wrap around the skeletons of modern-day mammals, including reindeer, polar bears, giraffes and elephants.

They discovered that the animals had almost exactly 21% more body mass than the minimum skeletal 'skin and bone' wrap volume, and applied this to a giant Brachiosaur skeleton in Berlin's Museum für Naturkunde.

Previous estimates of this Brachiosaur's weight have varied, with estimates as high as 80 tonnes, but the Manchester team's calculations – published in the journal Biology Letters – reduced that figure to just 23 tonnes. The team says the new technique will apply to all dinosaur weight measurements.

Lead author Dr Bill Sellers said: "One of the most important things palaeobiologists need to know about fossilised animals is how much they weighed. This is surprisingly difficult, so we have been testing a new approach. We laser scanned various large mammal skeletons, including polar bear, giraffe and elephant, and calculated the minimum wrapping volume of the main skeletal sections.

"We showed that the actual volume is reliably 21% more than this value, so we then laser scanned the Berlin Brachiosaur, Giraffatitan brancai, calculating the skin and bone wrapping volume and added 21%. We found that the giant herbivore weighed 23 tonnes, supporting the view that these animals were much lighter than traditionally thought.

Dr Sellers, based in Manchester's Faculty of Life Sciences, explained that body mass was a critical parameter used to constrain biomechanical and physiological traits of organisms.

He said: "Volumetric methods are becoming more common as techniques for estimating the body masses of fossil vertebrates but they are often accused of excessive subjective input when estimating the thickness of missing soft tissue.

"Here, we demonstrate an alternative approach where a minimum convex hull is derived mathematically from the point cloud generated by laser-scanning mounted skeletons. This has the advantage of requiring minimal user intervention and is therefore more objective and far quicker.

"We tested this method on 14 large-bodied mammalian skeletons and demonstrated that it consistently underestimated body mass by 21%. We suggest that this is a robust method of estimating body mass where a mounted skeletal reconstruction is available and demonstrate its usage to predict the body mass of one of the largest, relatively complete sauropod dinosaurs, Giraffatitan brancai, as 23,200 kg.

"The value we got for Giraffatitan is at the low range of previous estimates; although it is still huge, some of the enormous estimates of the past – 80 tonnes in 1962 – are exaggerated. Our method provides a much more accurate measure and shows dinosaurs, while still huge, are not as big as previously thought."

Tuesday, June 5, 2012

Neotropical Snakes That Span Gaps


Imantodes cenchoa

 Arboreal snakes can extend their bodies up to 50% of their length to bridge a gap between branches or perches under laboratory conditions. Morphological adaptations associated with this including lateral compression of the body, elongation of the tail, widening of ventral scales, forward-facing eyes that also can be aimed downward, and reduction in relative mass and the most agile species possess rigid muscles and tight skin, providing for more controlled movements and cantilevering. Specialized behaviors also play an adaptive role, but have been studied less because of the logistic difficulties of accessing and working in arboreal habitats.  A recent examination of cantilevering by Ray (2012) in adult snakes from Omar Torrijos National Park in Coclé Province, Panama used: Dipsas sp., Imantodes cenchoa, Oxybelis brevirostris, Sibon argus and S. annulatus. Also included were several less abundant species that were tested opportunistically and included I. inornatus, Leptodeira septentrionalis, and S. nebulatus. Species of Imantodes and Sibon exhibited the greatest ability to bridge distances in the experiments and they show the more highly adapted morphologically for arboreal habits. These species able to exploit smaller twigs, which facilitates movement between the ends of branches and subsequent cantilevering, presumably allowing these species to exploit food resources other snakes have difficulty reaching.

Citation
Ray, J.M. 2012. Bridging the gap: interspecific differences in cantilevering ability in a Neotropical arboreal snake assemblage. South American Journal of Herpetology 7:35-40.