Chapter 2

Biodiversity of the Western Ghats - An Overview
 - R.J. Ranjit Daniels



The Western Ghats, also known as the Sahyadri Hills, are well known for their rich and unique assemblage of flora and fauna. Norman Myers included the Western Ghats amongst the 25 biodiversity hot-spots identified in the world. Geologically the Western Ghats may be divided into two segments. The hills north of the Krishna basin (largely Maharashtra and Gujarat) with fragile basaltic rocks are results of the same processes that gave rise to the Deccan trap. Isolated, conical, flat-topped hills occur here with steep sides, marked with striations. They seldom rise beyond 1500 m. South of the Krishna basin is the region of precambrian archean crystalline hard rocks (nearly 2000 million years old granites, schists, gneisses, quartzites, etc). Soils vary from humus rich peat in the montane areas to laterite in the lower elevation and high rainfall belts. Soils are generally acidic.


Arising abruptly from the narrow Konkan and Malabar coasts, these hills run 1600 km north-south between the river Tapti in Gujarat and Kanyakumari in Tamilnadu covering an area approximately equal to 160,000 sqkm. In the east, they slope gently towards the Deccan Plateau. The northernmost segment that extends into Gujarat merges in the east with the Surat Dangs. In the Nilgiris, Palanis and parts of Karnataka, the Western Ghats extend considerably eastwards, locally merging with the Eastern Ghats. Towards the south, the hill chain is divided into two by the Palghat Gap (a mere 13 km gap at its narrowest) rendering a physically homogeneous high altitude plateau into two rather distinct biogeographic units viz., the Nilgiris complex in the north and the Anaimalai-Palnis complex in the south. Here are found the highest peaks viz., Anaimudi (Anaimalai Hills) and Doddabetta (Nilgiri Hills), reaching well over 2695 and 2637m ASL respectively. Apart from these, a number of peaks reaching heights of over 2000 m are present in the southern half as that in Tamilnadu (Palnis) and Kerala (eg. Highy Wavy Mountains and Grass Hills).


Climatic conditions in the Western Ghats vary with the altitude and physical proximity to the Arabian Sea and the equator. Although the Western Ghats experience a tropical climate - being warm and humid during most of the year with mean the temperature ranging from 20oC in the south to 24oC in the north, the higher elevations experience subtropical climates and on occasions frost. Further, it has been observed that the coldest periods in the southern Western Ghats coincide with the wettest.


Whereas rainfall peaks of 9000 mm and above per year, are known locally, annual rainfall as low as 1000 mm are frequent in the east bringing the average to around 2500 mm. Interestingly, the total amount of rainfall received and the spread are not often correlated. Areas in the northern Western Ghats (in the State of Maharashtra) receiving the highest rainfall (locally over 9000 mm) experience dry weather over more than half the year. On the contrary, areas receiving much less rainfall in Kerala and closer to the equator experience rain almost all through the year. Much of the rainfall is received during the southwest monsoon season. Peak period of rainfall is July-August. 

Origin and Prehistory

Peninsular India was part of the Gondwana land till about 150 million years ago, from which it split and started moving north. The northward drift which lasted about a 100 million years finally ended with the peninsula colliding with the Asian mainland 45 million years ago. Major geologic transformations took place as the peninsula moved northwards. Soon after detachment from the Gondwanaland, the Indian peninsula drifted over the Reunion Hotspots  - localised volcanic centres in the earth’s lithosphere, 200-300 km across, which have remained active for several million years.  It was this event that happened some 120-130 million years ago that resulted in the uplift of the Western Ghats. Subsequently, there were a series of volcanic eruptions until around 65 million years ago giving rise to the extensive Deccan Traps. These volcanic episodes to a large extent moulded the northern third of the Western Ghats. Since the Western Ghats are the result of domal uplift, the underlying rocks are ancient - around 2000 million years old.  The oldest of these rocks are found in the Nilgiris and the high ranges of the Western Ghats.


The uplifted crust of the earth bears a central axial region of weakness coinciding with the track of upliftment. Peninsular India broke along its line of weakness, and the western segment drifted westward into the sea (a process known as faulting), giving rise to the present day hill chain, the Western Ghats and the west coast. This happened during the Eocene (between 45 and 65 million years ago), even before India became part of the Asain mainland. At this time the peninsula also experienced a marked eastward tilt permanently changing the pattern of drainage. The western faulting led to ‘river capture’ and diversion of the easterly drainage to the west in many instances. The rivers Sharavathy and Kali in Karnataka are two classical examples of westerly diversion of drainage due to uplift and faulting. The Western Ghats thus represent a tectonically active region with high rates of uplift, high summit altitudes, steep slopes, deep gorges and large potential energy for erosion and correspondingly high sediment yields.


Modern biogeographers feel that the sp species of all vertebrates are endemic.  Amongst vertebrates, endemism is the highest in amphibians (78% species), followed by reptiles (62%), fish (53%), mammals (12%) and birds (4%) (Table 1).


Table 1: Endemic species of the Western Ghats



Very little fossil evidence exists to reliably reconstruct the prehistoric biodiversity of the Western Ghats. What we do know is that the flora of the Western Ghats share elements with Africa, Madagascar and South America (eg., Family Bignonaceae; Vinca rosea, etc). Many species of invertebrates including a few species of butterflies are also shared with South America and Africa. Amongst freshwater fishes there are a few genera (Notopterus, Barilius, Rasbora, Puntius, Labeo, Clarias, Aplocheilus, Mastacembelus, Garra, Aphanius) that are common to India and Africa represented by one or more species in the Western Ghats. Species of amphibians (especially caecilians) and reptiles (snakes in the genus Boiga for instance) may well have been there ever since the Western Ghats came into existence.  Most species of land birds and mammals that are seen in the Western Ghats today are those essentially derived from the eastern Himalayan-Malayan complex after peninsular India became part of Asia.


Table 2: Vegetation types of the Western Ghats






As early as 1904 Hooker had drawn attention to the distinct flora of the Western Ghats, which he called the ‘Malabar’ floristic region. The presence of Bambusae, Dipterocarpaceae, Guttiferae, Myristicaceae and Palmae (Arecaceae) has contributed to its distinctness. The various major vegetation types are tropical evergreen forests, moist deciduous forests, dry deciduous forests, scrub jungles, sholas, savannas including high rainfall savannas, peat bogs and Myristica swamps (Table 2).


Four thousand species of flowering plants are known from the Western Ghats. The gymnosperm flora is represented by Cycas circinalis (Cycadales), Decussocarpus wallichianus (Coniferales) and Gnetum ula and G. contractum (Gnetales). Amongst the lower plants around 320 species of pteridophytes, 200 species of bryophytes, 300 species of algae and 800 species of lichens are known. There are 600 species of fungi known from the Western Ghats.


Fifty-six genera of flowering plants are considered endemic to the Western Ghats. Recent studies have suggested that there could be 1500 species of flowering plants endemic to the Western Ghats. Although the exact number keeps varying with the author and time, what is of interest is that nearly 38% of all species of flowering plants in the Western Ghats are endemic. Sixty three per cent of India’s evergreen woody plants are endemic to the Western Ghats.




Scientific research on the invertebrates of the Western Ghats has largely been restricted to a few groups of organisms. As with any other tropical regions, the Western Ghats’ invertebrate diversity is best known by the butterflies (Table 3). Amongst other insects, ants of the Western Ghats are better studied for their habits and ecology.  While there are a number of studies undertaken on other invertebrates throughout the Western Ghats, few really address questions relating to ecology and biodiversity. Most of the studies on invertebrates are of a checklist nature or taxonomic.


Studies in Uttara Kannada district have suggested that ant species diversity in forests is linked to the woody plant species diversity. Elsewhere in the forests of Karnataka studies on ant communities have indicated that the common weaver ant Oecophylla smaragdina regulates the behaviour of other terrestrial ants that share its habitat. Whether such dominance by the weaver ant also has a bearing on the ant species diversity in the habitat is not yet clear. It has been observed that ants in the genus Leptogenys dominate ant communities in the Western Ghats.


Butterflies in the Western Ghats belong to five families, 166 genera and 330 species. Of these, 37 species are endemic. These 330 species of butterflies depend on over 1000 species plants for feeding and breeding. Diversity of butterflies in the Western Ghats is thus related to not only adult feeding habitats, but also larval food plants. Comparative studies on butterflies using selectively logged and unlogged forests in Kalakkad-Mundanthurai Tiger Reserve has suggested that butterfly diversity tends to increase in selectively logged habitats. However, it has been pointed out that this increase is due to the invasion by ubiquitous species at the expense of habitat specialists such as Idea malabarica.


Table 3: Distribution of butterflies in the Western Ghats



Many parts of the Western Ghats are still poorly explored for their invertebrate biodiversity. At the workshop on ‘Research priorities in tropical rainforests’ held in Coimbatore (February 27-28, 2001) the status of malacological studies in the Western Ghats was reviewed. It was apparent that most of the earlier works in the Western Ghats have under-represented the number of species of land and aquatic snails.


A few studies in the Western Ghats have paid attention to aquatic invertebrates including molluscs. During the early 1980s, a study of aquatic insects in the Nilgiris indicated that human interference in the upper Nilgiris has apparently reduced the diversity of species in seemingly undisturbed areas as Silent Valley. A decline in the diversity of aquatic invertebrates has also been noticed elsewhere in the Western Ghats. Habitat loss and pollution in Pune City have been attributed as reasons for the decline of aquatic insects and molluscs.




There are around 218 species of primary and secondary freshwater fishes in the Western Ghats. 53% of all fish species (116 species in 51 genera) in the Western Ghats are endemic (Table 4). Patterns of distribution and diversity of freshwater fishes in the Western Ghats are rather poorly understood. This is mainly due to the widespread construction of lakes, reservoirs and dams and the subsequent introduction of food and sport fish during the past 200 years. Despite the human interference of freshwater habitats in the Western Ghats, there are still some discernable patterns of fish distribution and diversity.


In general, the small and rapidly flowing hill streams support only a few species of specialised fish. Species poor fish communities are also seen in the higher elevation streams of the Western Ghats. Deep waters that are slow moving tend to support the highest diversity of fishes in the Western Ghats. Very deep waters as that in lakes, reservoirs and dams tend to be ideal for large sized and introduced species of fishes. They are not suitable for many smaller species that inhabit shallow, clear and rocky pools and streams.


Table 4: Diversity of endemic fishes in the Western Ghats



From what little has been understood of the distribution and diversity of freshwater fishes in the Western Ghats, it is apparent that the streams and rivers in the south are more diverse, including a larger number of endemic species, than those in the north.  A study of the freshwater fishes in the Kerala part of the Nilgiri Biosphere Reserve has suggested that the east and west flowing rivers in the region do not significantly differ in the number of species and those species exclusive to them – 69 species, 24 being exclusive in the east flowing rivers as against 68 species and 23 being exclusive in those flowing west.



One hundred and twenty one species of amphibians are known from the Western Ghats. The 121 species fall under 24 genera, six families and two orders. The family ranidae (true frogs) has the largest number of species (49) amounting to 42% of the amphibian fauna of the Western Ghats. The next largest family is rhacophoridae (treefrogs) with 30 species (25% of the amphibian fauna) (Table 5). In general, there are more species of terrestrial and arboreal amphibians in the Western Ghats than aquatic ones.


There is a remarkable diversity of caecilians in the Western Ghats. 16 out of 20 species known in India occur in the Western Ghats; all 16 being endemic. Caecilians prefer moist soils rich in organic carbon (essentially derived from rotting wood and leaf litter). The highest diversity of species in any given landscape is noticed in the southern half of the Western Ghats.


Table 5: Taxonomic breakup of the amphibian fauna of Western Ghats




Note: This table does not include the recently discovered amphibians and recent changes in nomenclature of Indian amphibians.


The north-south ranges of the 121 species vary from extremely widespread to highly restricted. Some are patchily distributed, while others show a more continuous distribution. Interestingly, species restricted to the south of 13o N latitude are more frequently patchily distributed. There is also a greater representation of species that prefer moist forests in those with patchy distribution.  When the patterns are analysed on a latitudinal scale, it turns out that species including Bufo melanostictus, Microhyla ornata, Ramanella montana, Euphlyctis cyanophlyctis, Limnonectes limnocharis, Hoplobatrachus tigerinus, Tomopterna breviceps and Polypedates maculatus are found over the entire range of the Western Ghats. These species (except Ramanella Montana) are also widespread in the country.


Most species are found in the altitudinal range of 0-1200 m ASL. Highest diversity of species is at 800-1000 m. Analaysis of the patterns of amphibian distribution in the Western Ghats has suggested that widespread rainfall, shorter dry season and a more uniform local climate have contributed to the high levels of diversity and endemism than elevation per se.




157 species of reptiles including a crocodile Crocodylus palustris is known from the Western Ghats. Majority of the reptile species are snakes. In all 97 species, representing 36 genera (2 genera of turtle/tortoise, 20 snake, 14 lizard) are endemic (Table 6). Endemism is highest amongst snakes, especially with the family Uropeltidae alone contributing 33 species. Amongst lizards, dwarf geckoes (Cnemaspis spp) and skinks (Ristella, Lygosoma, Mabuya and Scincella) have the maximum number of endemic species.


Table 6: Taxonomic breakup of reptilian diversity in   Western Ghats




Ecological studies of reptilian communities in the Western Ghats are those limited to the Kalakad-Mundanthurai Tiger Reserve. Survey-type studies of reptiles in the Western Ghats have provided the most information on species diversity and habitat use.  Higher diversity of species has been observed in the moist deciduous forests. As per one study in the Nilgiris, the number of reptilian species is negatively correlated with altitude, but positively correlated with number of herbs, number of fallen logs and slope. However, detailed studies in the Kalakad-Mundanthurai Tiger reserve have suggested that mid-elevations of 1000-1100m ASL in the Western Ghats have the highest diversity of reptiles. Further, the density of forest floor reptiles in the Western Ghats is generally low being 0.26 per 25 sqm.  It is interesting to note that snakes dominate the forest floor reptilian communities at altitudes of 1200m ASL and above.




Of all organisms, birds are the best studied in the Western Ghats. Beginning in the 1860s, British naturalists and planters were busy surveying the Western Ghats, collecting and describing the avifauna. Subsequent surveys by the Bombay Natural History Society (then led by Dr Salim Ali), the various state departments of forests, especially Kerala, many nature clubs and amateur birdwatchers have suggested that there are 508 species of birds, represented by nearly 600 forms of resident and migratory birds. Amongst the 508 species, 144 (28%) are aquatic birds including those which are found in the coastal habitats.  A total of 324 species (64%) are resident. These are predominantly land birds. Nineteen species may be considered endemic to the Western Ghats (Table 7).

Table 7: Endemic birds of the Western Ghats





Note: Small and isolated populations of the species marked with an asterisk exist here and there outside the geographical limits of the Western Ghats in peninsular India.


Broad patterns of distribution and diversity have been discerned in the birds of the Western Ghats. In general, most of the resident and typically forest birds are restricted in distribution to the Western Ghats southwards from Goa. Few endemic species extend north of Goa. In general, the endemic bird species of the Western Ghats are primarily birds of the rainforests and the higher elevation shola-grassland complexes.  In Kerala, the presence of some of the endemic birds (Malabar grey hornbill, Rufous babbler and Crimsonbacked sunbird) is associated with   greater abundance of mammals such as Nilgiri langur, Lion-tailed macaque and Sambar.


Locally, when equal areas are compared, there are more species of birds per unit area in the central parts of the Western Ghats, especially in the Uttara Kannada district. This is primarily due to mixing of migrants and generalist species of birds with the resident specialists and endemics. Wet evergreen forests and montane sholas, despite providing habitat to a number of specialists and endemic birds with greater conservation value, are comparatively less diverse in bird species than secondary/disturbed evergreen and moist deciduous forests.


Human interference of forests has led to the disappearance of birds locally in the Western Ghats. However, when large landscapes are considered, species richness of the avifauna has remained stable during the past 100 years. Whereas the floristic composition of woody plants determine the nature of bird species that might inhabit a forest in the Western Ghats, bird species diversity may be inversely related to woody plant species diversity, locally.  Monocultures in the Western Ghats may support an assemblage of birds as diverse as (or even more diverse than) evergreen forests. However, birds that inhabit the monocultures are often generalist habitat users drawn from a wide range of neighbouring habitats. Teak plantations may provide habitat to a number of species of birds in the Western Ghats. However, hole-nesting birds were found to avoid nesting on teak trees in monocultures.




One hundred and twenty species of mammals are known from the Western Ghats. Fourteen species are endemic (Table 8). The mammalian fauna of the Western Ghats is dominated by insectivores (11 species), bats (41 species) and rodents (27 species including the porcupine). Few studies have however paid attention to the community structure and organisation of these small mammals in the Western Ghats although there have been attempts to review our understanding of the status and ecology of smaller cats and lesser carnivores.

Table 8: Endemic mammals of the Western Ghats



Evergreen forests are particularly suited to frugivorous arboreal primates and squirrels while the deciduous forests offer the best habitat for the larger grazing herbivores like the gaur and deer. Drought resistant ungulates, particularly antelopes are specially adapted to the open dry scrub.  Elsewhere in the Western Ghats of Karnataka, the distribution and biomass of large herbivores have been studied. From this it emerged that the large herbivores biomass was highest in moist deciduous forests and adjacent teak plantations whereas it was the lowest in the dry deciduous forests.


Studies on other communities of mammals have been sporadic and more illustrative in nature. As mentioned before these studies have frequently addressed the smaller cats and lesser carnivores. Estimates of home ranges of civets and mongooses in the Western Ghats have suggested that the Indian Grey Mongoose (Herpestes edwardsii) and the Small Indian Civet (Viverricula indica) have monthly home ranges of 20.69-102 ha and 3.4-4.9 ha respectively. In another study of small carnivores in the Nilgiris it was found that civets were the most abundant (especially in evergreen forests) followed by mongooses, cats and marten. Canopy opening and the consequent weed infestation in evergreen forests adversely affects the civets.


At the scale of individual species, it has been found that endemic species of arboreal mammals including the spiny dormouse (Platacanthomys lasiurus) and the Nilgiri langur (Trachypithecus johnii) do not prefer evergreen forests that are either selectively logged or fragmented. The spiny dormouse is affected by habitat fragmentation. The food plants of the Nilgiri langur have been selectively lost in disturbed habitats.


The endemic primate Macaca silenus (Lion-tailed macaque or LTM) is amongst the few carefully studied mammals in the Western Ghats. In 1985, the population of this primate in the state of Karnataka was estimated as 3000. More recent estimates have placed the numbers in Karnataka around 1000-2000. A smaller population is known from Tamilnadu. Including the nearly 2000 individuals in Kerala, the population of LTM has been most recently placed at 4000. LTM is an inhabitant of evergreen rainforests, below 700 m ASL, with a home range of 1.25 sq km. Shape of the patches of these forests has a significant effect on the population of LTM. An opening of 0.5 sq km  of canopy may block the path of a moving troop of LTM.


The Nilgiri Tahr (Hemitragus hylocrius) exists in the higher elevations between Nilgiris and Ashambu Hills in the Western Ghats. Over this 400 km range, around 2000 animals are estimated to occur: 150 in the Nilgiris, 570-690 in Anaimalais, 890 in Eravikulam, 280-310 in Palani Hills and a handful over the rest of the range.


Asian Elephant (Elephas maximus) is another species of mammal that has attracted both scientific and popular interest. Recent estimates place the population of elephants in the states of Karnataka, Tamilnadu and Kerala at 12,500. A majority of this population is within protected areas in the Western Ghats. Unlike the LTM, the elephant is more of a habitat generalist utilising a wide range of natural and man-made habitats in and around the Western Ghats.


The Tiger (Panthera tigris) is comparatively better studied amongst other large mammals.  In the Western Ghats, the Tiger is presently restricted to states of Karnataka, Kerala and Tamilnadu. The exact population of this large and elusive cat is much less predictable than that of the Elephant, Nilgiri Tahr or LTM.  Study of the natural food habits of larger carnivores in Nagarhole has suggested that the Tiger selectively preys on animals weighing more than 176 kg. Non-selective predation by the Tiger on other animals is more likely the result of prey scarcity.


Human ecology and its impact on the biodiversity of the Western Ghats


The Western Ghats first came under human influences during the palaeolithic or old stoneage some 12,000 years ago (see Table 9). Stone tools used by palaeolithic people have been excavated in the river valleys of Palakkad, Mallapuram and Dakshina Kannada districts in the Western Ghats. Elsewhere, palaeolithic artifacts have been found in and around Mysore, Chickmagalur and Shimoga districts of western Karnataka.


Table 9: Chronology of human ecological events in the Western Ghats


Mesolithic sites (12,000-5000 ybp) have been discovered around the river Mandovi in Goa. Charcoal beds dating back to 5000 ybp in Tenmalai (southern Western Ghats) suggest that humans burnt forests around this time. During the new stoneage (5000-3000 ybp) there were domesticated cattle, sheep and goats in and around the Western Ghats. Whereas rainfed crops including millets and horse gram were cultivated, in Maharashtra the Jorwe people cultivated wet rice. Shifting cultivation was apparently the form of agriculture that predominated the Western Ghats till recently. Crops such as Eleucine coracana, Cajanus cajan, Ricinus communis, Panicum sumatrense, etc were mainly cultivated in this traditional system of agriculture.


Human influences have had varied impacts on the biodiversity of the Western Ghats. History of species extinctions in the Western Ghats was certainly coincident with the climatic and human histories. Extended arid periods and human interference starting 12,000 years before present, led to slow but extensive transformation of habitats in and around the Western Ghats. Unique landscape elements such as the Myristica swamps gave way to cultivation of rice. Along with the swamps, trees such as Myristica fatua var magnifica, Gymnacranthera carnatica, Semecarpus auriculata and the palm Pinanga dicksonii, disappeared locally.


The use of fire to clear forests for cultivation has had a major influence on the forests of the Western Ghats. The spread of bamboo and deciduous trees in the region would have been aided by this human practice. Widespread occurrence of fire tolerant trees such as Acacia catechu, Careya arborea, Dalbergia latifolia, Dillenia pentagyna, Schleichera oleosa, Tectona grandis, Terminalia spp and Xylia xylocarpa suggests this.


Hill agroecosystems in the Western Ghats are today dominated by estates - chiefly of tea, coffee, rubber and monocultures of various tree species, including the oil palm,  that was introduced lately. Available estimates indicate that above an altitude of 1500 m in the Western Ghats, there are 750 sq km of tea plantations. A total of not less that 1500 sq km are under coffee and 825 sq km under cardamom. It has also been highlighted that the Nilgiri district with a total area of 2549 sq km has around 1000 sq km under various forms of cultivation.


Casuarina plantations first appeared in Uttara Kannada district between 1868 and 1869. Till then the forest plantations were of native species. Teak was first raised as monocultures in 1840. The first teak plantation in Kerala was established in Nilambur in 1844. Over the years, eucalypts, cinchona, wattle, rubber, clove, etc, have displaced extensive patches of natural forests throughout the Western Ghats.


The impact of monocultures on the biodiversity of the Western Ghats has been little understood. In the Uttara Kannada district, monocultures were found to support as diverse a community of birds as natural forests.  The bird assemblage may however include a greater number of generalist species than the natural forests. As mentioned above, teak when raised as a monoculture fails to attract hole-nesting birds.


Apart from the introduction of commercially important plants, there have been invasions by a number of aggressive alien plant species. The British Colonists spread over most of the Western Ghats in the late seventeen hundreds and early eighteen hundreds. The Nilgiris were colonised only in 1813 almost 2000 years after the Todas did. Much of the exotic flora, especially those of temperate origin, came in after this. A large number of ornamental plants of temperate origin have since run wild in the higher elevations of the Western Ghats. For instance, in Palani Hills alone there are 600 such species especially, around Kodaikanal. Similarly, 400-500 introduced species of plants have been reported from the Nilgiris.


Important amongst these are Lantana camara (var aculeata), Eupatorium odoratum, Mikania cordata, Parthenium hysterophorus, etc. Wattle (Acacia sp) once introduced for the extraction of tannin in the higher hills is today a major threat to the sholas and grasslands at these altitudes. The impact of these exotic plants has been reason for a lot of debate. Contrary to general predictions, the presence of Lantana camara has not been detrimental to woody plant species diversity in the BR Hills.


In selectively logged evergreen forests, the woody plant species diversity has declined. This has been accompanied by the selective loss of certain plant species of greater economic value and an overall reduction in forest biomass. Other organisms have responded to human disturbance rather differently. Selective logging (consequently lower tree and canopy density) has locally increased the diversity of butterflies, lizards and birds in the Western Ghats. To balance the impacts of human interests with the long-term conservation of biodiversity in the Western Ghats is the greatest future challenge.




This summary is extracted from the National Biodiversity Strategy and Action Plan – Western Ghats Ecoregion, submitted to the Ministry of Environment and Forests, Government of India, in 2001. About 150 published and unpublished sources were consulted in the process.

Rhacophorous pseudomalabaricus : S.U. Saravana Kumar

Nilgiri Langur (Trachypithecus Johnii): A.K. Gupta