Saturday, May 1, 2010

Save the Frogs Day, April 30th 2010

Frog populations have been declining at an unexpected rate in the last few decades. Nearly one thirds of the worlds amphibians are threatened with extinction. Several species have already disappeared in the last few years.
It is now time for us to take serious steps to help conserve our Amphibians.Today being the Save the Frogs Day, lets us all decide to learn more about our little known amphibians and help in their conservation. Lets make every day a Save the Frogs Day.

Wednesday, March 3, 2010

Complete Feminization in Male Frogs due to the Use of Pesticide Atrazine

Scientist of the University of California, Berkeley and University of Cincinnati, have found that Atrazine (one of the most widely used pesticides and also a potent endocrine disruptor) exposure in adult male frogs cause complete feminization in the males. When male African Clawed Frogs (Xenopus laevis) were exposed to this pesticide, Ten percent of them developed into functional females that were able to copulate with unexposed males and produce viable eggs. The resulting larvae were all male when raised to metamorphosis and sampled, confirming that Atrazine-induced females were, in fact, chromosomal males. The Atrazine exposed males suffered from depressed testosterone, decreased breeding gland size, demasculinized laryngeal development, suppressed mating behavior, reduced spermatogenesis, and decreased fertility leading to complete feminization. Atrazine is also known to cause demasculinizes and feminizes exposed amphibian larvae, resulting in hermaphrodites.
Previous studies have shown that the Atrazine causes a reduction in sperm content in fishes like salmon, (Salmo salar) reptiles like caiman, (Caiman latirostris). The similarities between these previous findings in fish and in reptiles and the present findings in an amphibian suggest that the demasculinizing effects of atrazine are also not just species, genera, family specific but occur across vertebrate classes. The present findings exemplify that the role of Atrazine and other endocrine-disrupting pesticides, is likely a cause in the global amphibian declines.

Thursday, February 25, 2010

Cnemaspis Geckos of the Western Ghats

The Geckonid Genus Cnemaspis includes a group of diurnal geckos that ranges from South, South-East Asia and central Africa. Presently around 88 species of these Geckos have been recogniesd and the maximum diversity being from South and South-East Asia. Around 21 species of Cnemaspis geckos are found in South India of which 18 species are endemic to the Western Ghats. The Genus Cnemaspis can be easily identified from other geckos by their slender, clawed, non dilated digits and their round pupils. Although this group of geckos is fairly common throughout the Western Ghats, they remain to be one of the least understood gekonid genus of India. Recent studies on this genus have revealed several new species and have shed more light on their distribution and natural history.

During several visits throughout south India, I have been trying to understand more about this group of geckos. This note on the Cnemaspis geckos is posted to show the diversity of herpetofauna in the Western Ghats. The high endemism of the Western Ghats gives us more reasons for us to take urgent steps to protect and conserve it.

Sunday, January 10, 2010

New Light Shed On the Influence of Habitat Variables on the Distribution of Tadpoles of Nyctibatrachus major

Recent studies by K.G Girish and S.V Krishnamurthy of the Department of Environmental Science, Kuvempu University, Shimoga have found that the distribution of tadpoles and adults of the Large Wrinkled Frog, Niyctibatrachus major were influenced by canopy cover, Tree density near streams, leaf litter and humidity. Tadpoles were not found in streams were the soil, air and water temperature were high whereas tadpoles were found in streams were the canopy cover, tree density, leaf litter and humidity were high. The canopy cover, tree density and leaf litter reduced the light intensity and increased humidity providing the necessary temperature for the development of individuals. This study shows the importance of good forest cover for the development of tadpoles. Increased deforestation, timber extraction and stream modification may effect the population of this endemic frog. The IUCN has listed this species as vulnerable and if the present rate of deforestation continues, this species may well be on its way to extinction. It is by such studies that we can understand the complex relationship that a species has with its environment.

I sincerely congratulate and thank K.G Girish for sharing his findings with me and i wish him all the success in his quest to study and conserve amphibian.

Friday, November 20, 2009

Amphibian Endemics Of The Western Ghats

The Western Ghats or Sahyadri is a range of mountains that runs along the western coast of India. It stretches from the Satpur range in the north and ends in Kanyakumari in the southern tip of India. It is one of the 10 biodiversity hotspots with a high degree of endemic and endangered flora and fauna. This high endemism is due to its unique topography.
The Western Ghats is specially rich in its amphibian diversity. It has around 151 species of amphibians of which around 130 are endemic and found no where else in the world. Several genus such as Uraeotyphlus, Gegeniophis, Indotyphlus, Indirana, Ghatixalus, Micrixalus and Nictibatrachus are entirely endemic to the western ghats. The Southern western ghats is also the only home for the rare and primitive Purple frog (Nasikabatrachus sahyadrensis) which has changed little since the juracic period. The western ghats is also home to several species of amphibians yet to be described.
The impact of humans and our ecological amnesia has taken a huge toll on the amphibian diversity. Now this unique habitat lies in our hands. Habitat loss and fragmentation, pollution and global warming have had a direct impact on amphibians. Now it is time for us to take drastic steps to conserve them and their natural habitat.

Monday, November 9, 2009

Road Mortality: A Threat To Herpetofauna

The increase in road network throughout India has led to the increase in the road mortality of our Wildlife. This is greater in concern with our herpetofauna. The development in any area leads to increase in road network. The effect of these changes on the landscape effect fragile habitats such as the forests of the Western Ghats. Highways that pass through forested areas are a major cause for habitat fragmentation. This leads to the death of several species of amphibians and reptiles while crossing roads, when moving from one habitat to another. The effect of road mortality is greatest for endangered and endemic species of amphibians and reptiles.
During several visits to forests of the Western Ghats and surrounding areas, I have observed several road killed specimens. Several species of reptiles such as the Kerala Shieldtail (Uropeltis celynicus), Bronzeback (Dendrilaphis sp), Vine Snakes (Ahetulla nasuta), Wolf Snakes (Lycodon sp), Kukri Snakes (Oligodon sp), and Indian Garden Lizards (calotes versicolor) were found dead on the roads. Amphibians such as the Common Toad (Duttaphrynus melanostictus), Indian Bull Frog (Hoplobatrachus tigerinus) and Bicoloured Frog (Clinotarsus curtipes) were regularly found dead on roads. Most of the species found dead on the roads were nocturnal. Maximum road kills were observed after heavy rains. By understanding the regularities of road mortality of herpetofauna with respect to the changes in the environment, it is possible to take measures to control road mortality. Though a few studies have been carried out in few places in Tamil nadu, a detailed study throughout the Western Ghats is needed.
Most biologists may agree that many species of amphibians and reptiles need protection but, where the general public is concerned, reptile and amphibian conservation has a low priority. This attitude of the people can be changed only by educating them about the importance and the role that reptiles and amphibians play in our ecosystem. I consider education to be a synonym of conservation because unless we educate people about the importance of amphibians and reptiles, conserving them is next to impossible. Other ways to reduce herpetofaunal road mortality are by reducing vehicle traffic in forested areas during peak seasons and by finding alternative routs avoiding forested areas while moving from one place to another. So next time we see a road killed amphibian or reptile lets try to understand more about it rather than just complain, so that we can try and reduce road mortality of herpetofauna.

Wednesday, November 4, 2009

Pit Vipers Of The Western Ghats

Pit Vipers are a group of snakes belonging to the subfamily crotalinae. The Asian pit vipers are characterized by a stout body, a short prehensile tail and a broad sub triangular head with specialized heat sensing pits between the eye and the nostrils. They are venomous with specialized movable front fangs. Most of them are ovo-viviparous giving birth to live young.
The unique habitats of the Western Ghats is home to 6 species of pit vipers of which 4 are endemic to the Western Ghats and is found nowhere else in the world. Like all pit vipers they are venomous but their venom is not as toxic as other Indian venomous snakes and has resulted in very few fatalities. Their venom is adapted mainly to kill prey such as frogs, lizards, birds & rodents. The pit vipers of Western ghats belong to 4 genus which are

Trimeresurus: These are a group of stout snakes with a broad triangular head with small scales. The scales may be slightly keeled. They are mostly arboreal but can also be found on rocks. They are mainly found close to streams. They include 3 species in the Western Ghats.

  • Malabar Pit Viper (Trimeresurus malabaricus)
  • Bamboo Pit Viper (Trimeresurus gramineus)
  • Horseshoe Pit Viper (Trimeresurus strigatus)

Peltopelor: This is a monotypic genus containing only a single species. They are charecterised by their triangular head covered by large scales. They have a prehensile tail adapted for its arboreal habit. They can also be found on rocks close to streams. The distribution of this snake is restricted to a few highly elevated localities of Tamilnadu and Kerala. As mentioned above, it includes only a single species

  • Large-scaled Pit Viper (Peltopelor macrolepis)

Hypnale: The genus hypnale consists of small sized snakes with weakly keeled scales on the body. The head is broad, flat, and triangular and has large scales. The tip of the snout in these snakes is slightly upturned. They are mainly nocturnal and terrestrial inhabiting evergreen, moist and dry deciduous forests. This genus is distributed throughout the central and southern western ghats and Sri lanka. Only one species is know from the western ghats.

  • Hump-nosed Pit Viper (Hypnale hypnale)

Tropidolaemus: This genus is charecterised by distinctly keeled small scales on the snout and head and strong keels on the gular region. This group consists of a single species in India which is known only from two specimens from the southern Western Ghats.

  • Hutton’s Pit Viper (Tropidolaemu huttoni).

    Though most of these snakes except the Huttons Pit Viper are common throughout the western ghats, They are found nowhere else in the world. In recent days habitat loss and habitat fragmentation in the western ghats has caused a major threat to their existence. Hence conservation of the western ghats should be a major priority.

Monday, November 2, 2009

Ichthyophis bombayensis With Eggs

On 20, september of this year, during a butterfly survay at the Muthenga wildlife scantuary in waynad(Kerala), an unstriped caecilian (legless amphibian) was found under a piece of log, coiled around its eggs. The caecilian was around 45 cm long. The body was slaty brown above, lighter below. The position of the tentacle was just above the lip and closer to the eye than the nostrils. The first nucal groove was more prominent ventrally while the second was indistinct and visible only ventrally. Since the specimen was not disturbed around 44 eggs were counted. The eggs were transparent and the well developed embryo was seen moving inside the egg. The species was later identified as Ichthyophis bombayensis. Until recently 4 species of unstriped caecilians were known from the Western Ghats. Presently the DNA sequencing of these species revealed that the 4 species are closely related and the other 3 species(I.malabarensis, I. penensularis and I.
subterrestris) are now synonymised with Ichthyophis bombayensis.

Though few of the other groups were able to sight Tigers, Leopards and other game animals, I consider myself to be extremly lucky to find this enigmatic amphibian coiled around its eggs in the wild. I agree that many of the large mammals are endangered and need to be conserved. But we should not forget the smaller, less conspicuous animals.

Sunday, November 1, 2009

A Note on South Indian Agamid Lizards

Agamas are one of the most visible and commonly seen lizards throughout south India. Most of them are diurnal lizards that are they are active by day. They can be found on trees, rocky areas and in forested tracts of south India. They are mainly insectivorous. This family includes robust lizards characterized by a pair of well developed limbs, movable eye lids, round pupils, Subequal overlapping scales on the skin, head covered by small scales, belly scales not quadrangular and a long tail. Most of them have a spiny crest. Another interesting feature of the family Agamidae is the distinction of teeth into incisors, canines and molars. Most of these lizards are oviparous except a few which are viviparous. This family includes 6 geneses in South India.
Draco: These are small forest lizards with the ability to glide from tree to tree. They have a large membrane of skin on each side supported by ribs. They have a gular(throat) pouch and lateral flaps or wattles on each side of the neck. This genus is represented by only one species in South India which is endemic to the Western Ghats
  • Western ghats flying lizard (Draco dussumieri)

Sitana: They are common lizards found in the plains and forested tracts of throughout India. The body is compressed and covered over by regular keeled scales. Unlike other agamid lizards, they show the absence of a dorsal crest and in having only four toes on the hind foot. The males posses a large gular pouch. This genus is represented by a single species from India. Recent studies have revealed 3 more species of this genus from Nepal.
  • Fan-throated lizard (Sitana ponticeriana)

Otocryptis: They are forest dwelling lizards confined to the forests of the western ghats and Srilanka. Thhe body is compressed with the dorsal scales keeled. They have long slender legs which allow it to run on its hind limbs when threatened. They show the absence of a tympanum and a dorsal crest. Only one species is found in India which is endemic to a few places in the Western Ghats.
  • Indian Kangaroo Lizard (Otocryptis beddomii)
Salea: These are members of a genus restricted to the hilly areas of the Western Ghats. The body is compressed and covered with large, strongly overlapping scales. The males have both nuchal and dorsal crests. The tail is strongly compressed and crested above in males. Two species occur which are endemic to the Western Ghats.
  • Horsfield’s Spiny Lizard (Salea horsfieldi)
  • Anaimalai Spiny Lizard (Salea anamallayana)

Calotes: These are typical lizards of this family found in the plains and forested regions of India. Most of them are good climbers. They have a laterally compressed body with a crest of spines on the neck and also the body in some. They have an extremely long tail. The tympanum is very conspicuous. Most of the males have a gular sac and are known to change colour during the breeding season. Seven species are known from South India of which Calotes versicolor and Calotes calotes are found throughout South India. The other five species are endemic to the Western Ghats. The recently described Calotes aurantolabium is known only from the forests of KMTR, Tamil nadu. This species was first wrongly identified as
calotes andamanensis by Ishwar and Das and it was recently redescribed as Calotes aurantolabium by Shreyas Krishnan. The species belonging to this genus in South India are

  • Indian Garden Lizard (Calotes versicolor)
  • Green Forest Lizard (Calotes calotes)
  • Elliot’s Forest Lizard (Calotes ellioti)
  • Roux’s Forest Lizard (Calotes rouxii)
  • Large Scaled Forest Lizard (Calotes grandisquamis)
  • Nilgiri Forest Lizard (Calotes nemoricola) and
  • Calotes aurantolabium

Psammophilus: These are lizards found in hilly areas of peninsular India. They are well distinguished by their dorso-ventrally depressed body and long, slender tail. The body is covered with uniform keeled scales. They do not posses a dorsal crest. As the name suggests they are normally found in rocky habitats. There are tow species in India.
  • South Indian Rock Agama (Psammophilus dorsalis)
  • Dwarf Rock Agama (Psammophilus blanfordanus)