LIFE FORMS IN THE NORTHERN WESTERN GHATS

 

BY VARAD GIRI

Introduction

The Western Ghats is composed of five landscape scale corridors (CEPF-ATREE Report, 2009) and one of these is Sahyadri–Konkan corridor of Maharashtra and Goa in the northern Western Ghats. In this region there are excellent examples of the northern extremity of the richer forests of the Western Ghats.

But here the forest is more fragmented and is increasingly degraded by human exploitation (Rodgers & Panwar 1988). The less disturbed habitats in this region are mostly confined to the protected areas, which are still the strongholds of floral and faunal diversity. The uniqueness of this region is the presence of large laterite or basaltic plateaus on the crest of mountains. The forest, mostly semi-evergreen, is in the valleys. Most of these plateaux are with scanty vegetation, which is mostly evident in monsoon and in summer they look barren. These forests are also abode for larger fauna like Tiger, Leopard, Indian gaur, Sambar and many interesting birds. Apart from their unique ecological features, these plateaus have a unique floral and faunal diversity (Giri & Bauer 2008). Despite its varied habitat features and unique diversity, the northern Western Ghats, especially the parts in Maharashtra, remain relatively poorly known. Though there are a few preliminary but intensive surveys for caecilians in particular, the region is grossly understudied. This is evident by the fact that recent moderate field efforts have so far resulted in the discovery of one new genera and species of toad (Biju et al. 2009), three new species of caecilians (Giri et al. 2003, 2004; Ravichandran et al. 2003) and two new species of geckos (Giri & Bauer 2008; Giri et al. 2009), from easily accessed localities. All these newly described species are endemic to this region and are highly habitat specific thus needs immediate attention and protection for their effective conservation.

Potential threats

The non protected areas in this region are under tremendous anthropogenic pressure. These forests are not protected so deforestation is rampant in this region. The mining activities are also increasing and their main target is the plateaus. The other pressures are in the form of agricultural practices and cattle grazing. This in return is resulting in heavy habitat loss

and fragmentation of contiguous habitat. Interestingly the effort towards assessment and documentation of this loss is very meager. Thus proper conservation measures are essential to regulate this loss and if not then this unique habitat and its diversity will vanish without our knowledge.

An effort towards the conservation of these habitats

One of the efforts towards conservation of Baraki, Amba and Amboli forests, Bombay Natural History Society in collaboration with the local NGOs, Green Gaurds of Kolhapur and Malabar Nature Conservation Club of Amboli initiated a study on the documentation of herpetofauna of this region from 2006. This ongoing activity has already resulted in the interesting findings like new locality reports for toad Xanthophryne tigerinus and a rare snake Rhabdops olivaceous. These species are endemic to the Western Ghats are known from a few localities. The report of first ‘live bearing’ amphibian from Asia (Gower et al. 2008) is also a result of this activity. Another major outcome is the description of a new species of

snake from Amboli and northernmost locality report of Ceylon Frogmouth Batrachostomus moniliger and Stripe-necked Mongoose Herpestes vitticollis from Amba Reserve Forest.

An overview of the unique amphibians and reptiles of this region >

This area is exceptional for its unique diversity of amphibians and reptiles. There are reports of 53 species of amphibians and around 90 species of reptiles from Maharashtra. Though most of these species are known from the Western Ghats mountains, they are highly concentrated in its southern and middle part, the area which is proposed as World Heritage Site. Some of the unique and interesting amphibians and reptiles of this region are: 

Amphibians

These are the indicators of healthy and unpolluted environment as they require clean surrounding for their survival. Though the amphibians are not very seriously studied, there are reports of about 53 species of amphibians from Maharashtra. This comprises of eight species of caecilians and remaining are frogs and toads. Following are some details of the unique and endemic amphibians of this region.

Caecilians

Caecilians are legless and burrowing amphibians and are considered as rare. There are reports of 33 species of caecilians in India of which 22 are endemic to the Western Ghats. In Maharashtra this group is represented by eight species belong to three genera and two families. There are reports of about six species of caecilians from the proposed area. There are a few more species which are not yet identified as the work on their proper taxonomy and identification is in progress. The uniqueness of this region is the occurrence of the endemic genus Indotyphlus. The only known species of ‘live-bearing’ amphibian from Asia, a caecilian is reported from this region. Interestingly the caecilians from this region have varied habitat preferences and a few species are reported from plateux, which was considered as an unsuitable habitat for these burrowing amphibians.

Genus – Indotyphlus

This is an endemic genus of the northern Western Ghats and is represented by two species, I. battersbyi known from Lonavala, Khandala and Matheran and I. maharashtraensis only known from Koyna Wildlife Sanctuary and Kaas.

Indotyphlus maharashtraensis was discovered from near Koyna Wildlife Sanctuary in 2003. This is one of the interesting species and is only known from laterite plateaus and adjoining forests of the Koyna Wildlife Sanctuary. There are some recent reports of this species from near Kaas plateau also. This is one of the restricted range species as its distribution is in a very small region.

The type locality of Indotyphlus maharashtraensis is approximately 150 km south of the known provenance of I. battersbyi, and at a similar altitude. These are the most northerly confirmed localities for any Western Ghats caeciliids and they receive less rain for less of the year than more southern Western Ghats localities, particularly in Kerala and Tamil Nadu, where caecilian diversity has previously seemed particularly high. Both species are mostly seen during the monsoon season in similar habitats often under rocks in open, grassy, shallow-soiled areas within strongly seasonal, semi-evergreen or deciduous vegetation without perennial surface water. Such habitats might be considered atypical for terrestrial caecilians, which are generally known more from moist soils and litter, and they would appear to be inhospitable environments for caecilians during the long dry season.

Genus – Gegeneophis

In India this genus is represented by nine species, of which eight are endemic to the Western Ghats. There are confirmed reports of three species of Gegeneophis in the proposed area. All of these are recently described species are of Data Deficient conservation status. 

Gegeneophis seshachari is another recently described species and is apparently one of the widely distributed species of the caecilians in the northen Western Ghats with wide habitat preferences. But the recent studies on molecular phylogenetics of this species show much greater genetic diversity exists within populations referred to G. seshachari such that some populations likely represent undescribed species. Interestingly this is one of only known species of amphibians in Asia which is live bearing.

The other species Gegeneophis danieli is also discovered in 2003. This species was known from only one locality, Amboli in Sindhudurg district. In one of the recent studies there are reports of this species from Radhanagari Wildlife Sanctuary also. These caecilians are mostly restricted to the forested habitats and are not been reported from the degraded forest patches nearby.

Apart from this there are reports on the occurrence of some unidentified caecilians of genus Ichthyophis from different localities in the proposed area. As per the preliminary observations some of these caecilians may be undescribed species.

Frogs and Toads

This group of amphibian is represented by about 42 species in Maharashtra. There is occurrence of one endemic genus and species of toads in the proposed area.

Genus – Xanthophryne (earlier Bufo)

Recent molecular phylogenetic analyses have revealed a radiation of toads (Adenominae) with distinct adult and larval ecomorphs on the Southern parts of the Indian subcontinent. Of this one genus Xanthophryne is endemic to the Western Ghats region of Maharashtra. There are two species in this genus and they show a very patchy distribution. These toads

are mostly seen on the plateaus and have a very unique breeding behaviour as they lay their eggs in small water which accumulates on the lateritic rocks. Unlike most of the other toads the eggs are not laid in the form of a chain. The metamorphosis takes place in such shallow water.

Xanthophryne koynaensis is presently only known from the Koyna Wildlife Sanctuary. As mentioned earlier, these toads, though seen in large numbers in places where they are found, they are mostly confined to the plateaus and rarely in the forests. Interestingly there are no reports of this species on the nearby plateaus like Kaas and Thosegar in Satara Disctict.

Due to their unique breeding behaviour, this particular species is facing broblems during monsoon. Due to intermittent their eggs and tabpoles are drying and this in long run may create problem for the survival of this species.

Genus - Nyctibatrachus

The frogs of this genus are also endemic to the Western Ghats. They are mostly seen along the forest streams and are highly sensitive to the changes in the environment. The forest of Mahabaleswar is unique as this is the type locality of one interesting frog Nyctibatrachus humayuni. This species is also known from Koyna Wildlife Sanctuary.

Reptile

As mentioned earlier, there is very little information available on the reptiles of this region which is mainly due to lact of proper studies. Although, some preliminary studies resulted in the description of new species from this region. Interestingly the plateaus mostly support the reptile diversity which is mostly seen in the drier parts. And the reptile diversity in the forest mostly consist of a few widely distributed and many Western Ghats endemics. The proposed area is has some interesting and endemic species of lizards and snakes.

Lizards

Due to the varied habitats, this region has a good diversity of lizards. In the proposed area there are reports of three species of endemic lizards.

Hemidactylus sataraensiss

This is an endemic species of a lizard from northern Western Ghats and is known from a patch of 30 sq. km. near Kaas Plateau in Satara District. Unlike most of its congeners, which are arboreal, this gecko is strictly terrestrial and is seen under the rocks. This species is also confined to the lateratic plateaus. As per the preliminary observations, they are mostly seen in the monsoon and winter and disappear in the summer. Very little information is available on the natural history of this species and this it is Data Deficient conservation status.

Cnemaspis kolhapurensis

This is also an endemic species and is only known from a single locality in the Radhanagari Wildlife Sanctuary. This species is mostly seen under the rocks and in the leaf litter in the forested habitat. Their scales are lustrous and this probably the only known gecko species in the world to have such unique character.

Geckoella deccanensis

This is comparatively a common and widely distributed species but is endemic to the Western Ghats region of Maharashtra. This forest dwelling species is mostly seen under rocks, logs and in the leaf litter. It is reported from most of the localities in the proposed site.

Snake

Although least studied, the proposed site is an abode to some interesting and endemic species of snakes.

Uropeltis macrolepis mahabaleshwarensis

The snakes of this genus are mostly confined to the Western Ghats. One of the best examples of endemism in Maharashtra is Uropeltis macrolepis mahabaleshawarensnis. This burrowing species of a snake is only known from Mahabaleshwar. There are some unconfirmed reports of this species from Koyna Wildlife Sanctuary.

Rhabdops olivaceous

This snake is also endemic to the Western Ghats. Considered as one of the rarest snakes in India, is commonly seen in many localities in the proposed area. Interestingly they are seen in the monsoon on the plateaus and in the forests streams.

These are some of the known representatives of amphibians and reptiles of the northern Western Ghats, Maharashtra.

 

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