December 21, 2013
The heavily forested mountains of the Eastern Himalayas are a hotspot for biodiversity. In a stunning discovery scientists have found a genus of frogs living in Assam and Arunachal Pradesh that was thought to be extinct, while another team has discovered a new bird species.
The bright yellow-bellied frog was discovered by an international team of wildlife researchers led by Dr Sathyabhama Das Biju from Delhi University. Biju is also known as ‘the frog man of India’ because he is credited with discovering and identifying 89 out of the 388 frog species found in India during the last 25 years of his work. The newest frog discovered by his team has been called Frankixalus Jerdonii. The explorations began in 2007, but it took almost a decade for the experts to conclude through DNA assessments that it was a whole new genus and not just a new species.
Discovering an “extinct” frog
The sighting of Frankixalus is much needed good news for the world of conservation science. This creature – earlier found in Assam, Arunachal Pradesh and the north-east belt as well as in Tibet – had not been sighted for nearly 150 years and was considered extinct.
Scientists feel that the frog remained elusive for such a long period possibly because it is a tree hole frog and hence remained hidden in the hollows of trees and bamboo stems. They also speculate that this frog, originally known as Jerdon’s tree frog, is no longer found in the area where it was first discovered and its current habitats are poorly surveyed.
“The amphibians of the northeastern Indian region are still not properly explored, and we believe this region is home to several unique frog species, which are yet to be discovered and described,” Biju told thethirdpole.net.
Recounting how they chanced upon this extraordinary discovery, Biju said, “During one of our amphibian expeditions in the forests of Northeast India, we heard some distinct frog calls [tree hole frogs use the trees as “megaphones”] from higher up in the canopy. This was in the late evening hours, immediately after some sporadic rain showers. After a few days of extensive fieldwork we located this frog for the first time in 2007. At that time, we did not know the identity of this frog. Then over the subsequent years, we conducted some specific surveys to study this species and its breeding behaviour. It took us almost six years to complete our study.”
A completely different type of frog
This frog also exhibits behaviour that is rarely seen in other frogs, giving the scientific community more to explore. For instance, it displays a unique form of parental care in which the mother lays eggs for the tadpoles to feed upon. These tadpoles survive on these eggs until they metamorphose into froglets. According to Biju, “This rare form of parental care behaviour has been reported for the first time from India.”Frankixalus differs from frogs of all known tree frog genera by a combination of characters like external appearance, skeletal features, unique tadpoles, breeding behaviour and DNA.
“This frog is special because of several reasons. Firstly, it is a canopy dwelling species. These frogs breed inside high canopy tree holes. Female frogs lay eggs on the inner walls of tree holes. Free-swimming tadpoles hatch out of these eggs and undergo development inside the same water-filled tree hole cavities, “added Biju.
An indicator of the health of the ecosystem
There are some 7,000 frog species in the world but these creatures are very sensitive to their habitat. As a result they are vanishing rapidly due to habitat destruction and changing climate. It is believed that nearly 100 frog species remain undiscovered in India and there is a fear that many of these species could be wiped out even before their discovery.
“We are concerned about their future. Frogs in the new genus have very specific microhabitat requirements. They require tree holes to complete their breeding cycle. Therefore, habitat destruction is a major concern. Threats like deforestation could wipe out a complete population of this frog from an area. As with many other species in the northeastern states of India, the habitat of this new frog is also degrading,” said Biju.Frogs are not just crucial indicators of the health of ecosystem but they are also very vulnerable and sensitive to any change in the climate. Biju told thethirdpole.net, “Amphibians are cold-blooded animals. They have permeable skins and a biphasic life. That means, a part of their life cycle, right from eggs until they metamorphose into adults, is completely dependent on water or moisture. After metamorphosis, frogs lead a life on land. Because of these factors, amphibian breeding and especially its timing is controlled by temperature and moisture. Any small changes in the climate or weather patterns can have a drastic impact on amphibian populations, and can sometimes wipe them out from an area.”
The discovery of the rare frog was not the only piece of good news, as scientists found a new species of bird through its unique birdsong, again in Arunachal Pradesh. A team of researchers from Sweden, India, China, the US, and Russia named the bird Zoothera salimalii, as a tribute to late Salim Ali, India’s most famous ornithologist.While studying birds at high elevation of the mountainous Arunachal Pradesh, researchers found that there were two distinct species of plain-backed thrush which had earlier been considered as one species. Although both the species look similar but their songs are strikingly different, apart from this the researchers found that these two species of birds were completely “segregated by elevation and habitat, one occurring in mostly coniferous forest up to the upper tree limit and the other in alpine habitats above the tree limit.”
A release by the scientists also said that “the studies of specimens from 15 museums in seven countries revealed consistent differences in plumage and structure between birds from these two populations. It was confirmed that the species breeding in the forests of the eastern Himalayas had no scientific name. Later, the new species was named as Himalayan Forest Thrush Zoothera salimalii. The high-elevation Plain-backed Thrush is now renamed as Alpine Thrush while it retains the scientific name of Zoothera mollissima.”
The discovery of these new creatures is a source of joy, but also of concern as the rich forests of the eastern Himalayas that are home to vulnerable and fragile populations of such elusive but crucial species are under threat due to deforestation, and climate change.