Sunday, March 22, 2009

Vanishing Species - Leatherback Turtle

An article by Mohan Pai

Leatherback Turtle

Dermochelys coriacea

Illustration: Courtesy Canadian Museum of Nature

The longest-living marine species ever to ply world’s oceans, their survival intothe next decade is doubtful.

They are the longest-living marine species to ever ply the world's oceans. They survived catastrophic asteroid impacts and outlived the dinosaurs. But the leatherback sea turtle, the largest turtle in the world, is on the brink of extinction, and scientists question whether the animal will survive into the next decade. Over the last 22 years their numbers have declined in excess of 95 percent .

The leatherback turtle is the largest of all living sea turtles. and is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its carapace is covered by skin and oily flesh. Instead of teeth the Leatherback turtle has points on its upper lip. It also has backwards spines in its throat to help it swallow food. Leatherback turtles can dive to depths as great as 4200 feet (1,280 meters).The leatherback turtle is entirely at home in the sea but comes to the shores to lay its eggs on sandy beaches. Cold blooded animals that they are, turtles live life in slow motion and live for hundred years or more. The leatherback turtle is a species with a cosmopolitan global range. In India leather backs come to the beaches of Kerala and Andaman and Nicobar islands where their eggs are a much prized food. This egg collection now threatens the existence of many sea turtle species. But notably enough, some fishing communities from Tamil Nadu have the tradition of not finishing off all the eggs in the clutch, but always leaving behind one, thus ensuring long time persistence of the race.
Leatherback turtles have a flattened, round body with two pairs of very large flippers and a short tail. Like other sea turtles, the leatherback's flattened forelimbs are specially adapted for swimming in the open ocean. Claws are noticeably absent from both pair of flippers. The leatherback's flippers are the largest in proportion to its body among the extant sea turtles. Leatherback front flippers can grow up to 2.7 meters in large specimens, the largest flippers (even in comparison to its body) of any sea turtle. As the last surviving member of its family, the leatherback turtle has several distinguishing characteristics that differentiate it from other sea turtles. Its most notable feature is that it lacks the bony carapace of the other extant sea turtles. Instead of scutes, the leatherback's carapace is covered by its thick, leathery skin with embedded minuscule bony plates. Seven distinct ridges arise from the carapace, running from the anterior-to-posterior margin of the turtle's back. The entire turtle's dorsal surface is colored dark grey to black with a sporadic scattering of white blotches and spots. The turtle's underside is lightly colored.The adults average at around one to two meters long and weigh from around 250 to 700 kilograms. The largest ever found however was over three meters from head to tail and weighed 916 kilograms. That particular specimen was found on a beach on the west coast of Wales in the North Atlantic.Leatherbacks are also the reptile world's deepest-divers. Individuals have been discovered to be able to descend deeper than 1,200 meters (3,937 feet).They are also the fastest reptiles on record. The 1992 edition of the Guinness Book of World Records has the leatherback turtle listed as having achieved the speed of 9.8 meters per second (35.28 kilometers per hour) in the water.
Of all the extant sea turtle species, the leatherback has the widest distribution, reaching as far north as Alaska and Norway and as far south as the Cape of Good Hope in Africa and the southernmost tip of New Zealand. The leatherback is found in all tropical and subtropical oceans, and its range has been known to extend well into the Arctic Circle. Globally, there are three major, genetically-distinct populations. The Atlantic Dermochelys population is separate from the ones in the Eastern and Western Pacific, which are also distinct from each other. A third possible Pacific subpopulation has been proposed, specifically the leatherback turtles nesting in Malaysia. This subpopulation however, has almost been eradicated. The beach of Rantau Abang in Terengganu , Malaysia, had once had the largest nesting population in the world with 10,000 nests per year. However in 2008 only 2 leatherback turtles nested at Rantau Abang and unfortunately the eggs where infertile. The major cause for the decline in the leatherback turtles is the practice of egg collection in Malaysia. While specific nesting beaches have been identified in the region, leatherback populations in the Indian Ocean remain generally unassessed and unevaluated.
Like all sea turtles, leatherback turtles start their lives as hatchlings bursting out from the sands of their nesting beaches. Right after they hatch, the baby turtles are already in danger of predation. Many are eaten by birds, crustaceans, other reptiles and also people before they reach the water. Once they reach the ocean they are generally not seen again until maturity. Very few turtles survive this mysterious period to become adults. It is known that juvenile leatherbacks spend a majority of their particular life stage in more tropical waters than the adults.

Adult leatherbacks are prone to long-distance bouts of migration. Migration in leatherback turtles occurs between the cold waters in which mature leatherbacks cruise in to feed on the abundant masses of jellyfish that occur in those waters, to the tropical and subtropical beaches in the regions where they were hatched from. In the Atlantic, individual females tagged in French Guiana off the coast of South America have been recaptured on the other side of the ocean in Morocco and Spain.Mating takes place at sea. Leatherback males never leave the water once they enter it unlike females which crawl onto land to nest. After encountering a female (who possibly exudes a pheromone to signal her reproductive status) a leatherback male uses head movements, nuzzling, biting or flipper movements to determine her receptiveness. Females are known to mate every two to three years. However, leatherbacks have been found to be capable of breeding and nesting annually. Fertilization is internal, and multiple males usually mate with a single female. However, studies have shown that this process of polyandry in sea turtles does not provide the offspring with any special advantages.While the other species of sea turtles almost-always return to the same beaches they hatched from, female leatherback turtles have been found to be capable of switching to another beach within the same general region of their "home" beach. Chosen nesting beaches are made of soft sand since their shells and plastrons are softer and easily damaged by hard rocks. Nesting beaches also have shallower approach angles from the sea. This is a source of vulnerability for the turtles because such beaches are easily eroded. Females excavate a nest above the high-tide line with their flippers. One female may lay as many as nine clutches in one breeding season. About nine days pass between nesting events. The average clutch size of this particular species is around 110 eggs per nest, 85% of which are viable. The female carefully back-fills the nest after, disguising it from predators with a scattering of sand.

A leatherback turtle has set the record for 'the longest trip for marine vertebrae between breeding and feeding sites'. It swam 20,558 kilometres, non-stop for 647 days!

Acknowledgements: Wikipedia, National Geographic, Canadian Museum of Nature

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Monday, March 16, 2009

Vanishing Species - Indian Muntjac

An article by Mohan Pai

Indian Muntjac
Muntiacus muntjak

Also called the Barking deer. Its call from a distance sounds much like the bark of a dog and hence the name.

The more common of the two small forest ruminants, the Indian Muntjac (Muntiacus muntjak) is also commonly called the "barking deer" due to the bark-like sound that it makes as an alarm when danger is present. Sometimes these deer will bark for an hour or more. The Indian Muntjacs specifically are widespread throughout Southern Asia, but are one of the least known Asian animals. It is hunted for its meat and skin. Often, these animals are hunted around the outskirts of agricultural areas because they can be considered a nuisance damaging crops and ripping bark off of trees.

The Indian Muntjac has a short but very soft, thick, dense coat, especially those living in cooler regions. Coloration of the coat changes from dark brown to yellowish and grayish brown depending on the season. The Muntjacs' coat is golden tan on the dorsal side and white on the ventral side of the body, the limbs are dark brown to reddish brown, and the face is dark brown. However, the ears have very little hair which barely covers them. Male muntjacs have antlers that are very short, about 1-2 inches, usually consisting of only two or three points at the most and protrude from long body hair covered pedicels on the forehead. Females have tufts of fur and small bony knobs where the antlers are located in males. Males also have slightly elongated upper canines about an inch long that curve slightly outward from the lips and have the capability to inflict serious injury upon other animals or to other members of the population while exhibiting aggression. Males are generally larger than females. The body length of Muntjacs varies from 35-53 in. and their height ranges from 15-26 in.


The Indian Muntjac is the most widespread but least known of all the animals in South Asia. This species is distributed throughout South Asia, but more densely located in Southeastern Asia. The Muntjac Prefers hilly and moist areas in thick deciduous forest. They are found throughout India except J&K, High Himalayas and arid/desert areas of Gujarat and Rajasthan. They never wander far from water. Also, males usually have their own territory which may overlap the territories of a few females but not of another male.


The Indian Muntjacs are classified as omnivores. They are considered both browsers and grazers with a diet consisting of grasses, ivy, prickly bushes, low growing leaves, bark, twigs, herbs, fruit, sprouts, seeds, tender shoots, bird eggs and small warm-blooded animals. Indian Muntjacs are typically found feeding at the edge of the forest or in abandoned clearings. Their large canines help in the processes of retrieving and ingesting food.


The Indian Muntjacs are polygamous animals. Females sexually mature during their first to second year of life. These females are polyestrous, with each cycle lasting about 14 to 21 days and an estrus lasting for 2 days. The gestation period is six to seven months and they usually bear one offspring at a time but sometimes produce twins. Males often fight between one another for possession of a harem of females. There is no evidence of a specific breeding season within the species.


Indian Muntjacs are regarded as extremely solitary animals, rarely observed with other muntjacs, except for a mother and her young and during the rutting season. Males acquire territories that they mark with scent markers. These deer are incredibly alert creatures. When put into a stressful situation or if a predator is sensed, Muntjacs will begin making a bark-like sound. Barking was originally thought of as a means of communication between the deer during mating season as well as an alert. However, in more recent studies it has been identified as a mechanism used solely in alarming situations meant to cause a predator to realize that it has been detected and move elsewhere or to reveal itself.

Pic courtesy:
References: Wikipedia, A field guide to Indian Mammals by Vivek Menon,The book of Indian animalsby S. H. Pratter.

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Saturday, March 7, 2009

Vanishing Species - Jerdon's Courser

An article by Mohan Pai

Jerdon’s Courser

Rhinoptilus bitorquatus

The Jerdon's Courser (Rhinoptilus bitorquatus) also known as Doublebanded Courser, is a nocturnal bird belonging to the pratincole and courser family Glareolidae endemic to the Eastern Ghats of Andhra Pradesh. The bird was discovered by the surgeon-naturalist Thomas C. Jerdon in 1848 but not seen again until 1986.
Naturalists searched for it in its native habitat in eastern India but without success. In 1975/76 the Bombay Natural History Society (BNHS) launched another search for it. The BNHS circulated posters showing a coloured picture of the bird in the Pennar river valley in southern Andhra Pradesh. There was a note in Telugu accompanying the posters. One day a tribal said he had seen the bird shown in the poster and that it was known as Kalivi-Kodi in Telugu. He said the birds moved in groups of seven to eight and fed at night.
In January 1976 a poacher caught a Kalivi-Kodi but by the time a representative of the BNHS reached him the bird had died. But the scientists were closing in on the bird and soon afterwards they saw some of them in their natural surroundings. They watched entranced. Their long search was over!The kalivi-kodi was indeed Jerdon's Courser and it was alive and well!
Historically, it was known from just a few records in the Pennar and Godavari river valleys and was assumed to be extinct until its rediscovery around Lankamalai in 1986. It has since been found at six further localities in the vicinity of the Lankamalai, Velikonda and Palakonda hill-ranges, southern Andhra Pradesh, with all localities probably holding birds from a single population.
Still, with only a few birds sighted, today the Jerdon's Courser is categorized as critically endangered in the World Conservation Union's Red List and is also listed under Schedule I of the Indian Wildlife (Protection) Act 1972, and is considered as priority species under the National Wildlife Action Plan (2002 – 2016) of the Government of India.
This bird was known only from a few historical records and was thought to be extinct until its rediscovery in 1986. It remains critically endangered due to loss of habitat. It is nocturnal in habit and presumed to be insectivorous. Being a rare bird, nothing is known yet about its behaviour and nesting habits.Population estimates for the bird range from between 25 and 200. Recent studies have made use of techniques such as camera trapping and carefully placed strips of fine sand to record footprints from which estimates of population density are made. The known world population of the species is restricted to a very small region and attempts have been made to find new areas by distributing pictures and small electronic call players to people in neighbouring regions that share similar habitats.In 1988 the Indian Postal Service released a stamp to commemorate the rediscovery.

Given that it is so poorly known, it is difficult to identify specific threats, although its habitat is becoming increasingly scarce and fragmented. Following the construction of the Somasilla Dam, 57 villages were displaced and relocated within the Lankamalai, Palgonda and Seshachellam areas, which were previously inaccessible. The dependence of the settlers on the area for resources may pose a serious threat to
habitat through fuelwood-collection and livestock-grazing, and to the birds themselves through increased disturbance. In addition, extensive quarrying is destroying habitat.
The habitat area of Jerdon’s Courser
Suitable habitat for the species lying outside Sri Lankamaleswara Wildlife Sanctuary is threatened by the proposed construction of the Telugu-Ganga Canal in Cuddapah District, although mitigation measures proposed will result in an increased area of habitat becoming available for management by the Forestry Department.

References: Wikipedia, Birdlife International, Dimdima kids (Bharatiya Vidya Bhavan)