Friday 9 September 2016

Why is endemism important ?

Endemism as Wikipedia puts it can be defined as an ecological state of a species being unique to a defined geographic location, i.e. an island, nation, country, range, zone or a particular habitat type. The Western Ghats of India is a hotspot for endemic birds with close to twelve species being found only here and nowhere else in the world. The Ghats un along the western edge of the Deccan plateau in Peninsular India starting just north of Bombay and ending in the south at the tip of the peninsula. Most of the endemics can be found distributed in highly restricted localities in the states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu, although a few of these restricted-range species have also recorded from disjunct localities in the hills to the east, in northern Tamil Nadu and southern Andhra Pradesh. The levels of endemism among these restricted range species varies to a great deal with seven out of the sixteen endemics being found from sea level to c. 1500 mtrs across the Ghat ranges. While some species like the White-Bellied Shortwing can be found mainly above elevations of 1500 mtrs and in select patches in these hills. Another bird that is hard to come across and can be found only in select locations is the Black and Orange Flycatcher.
                                 

The Nilgiri Flowerpecker, endemic to the Western Ghats, but found distributed across a wide area.  (©Joiston Pereira)
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The question then arises as to why endemics are so important to an ecosystem. Endemic birds are extremely selective in their habitat preferences and minor changes in their habitats will have cascading effects on the distribution and population of these birds. For example birds that are restricted to selected patches and colonize the moist understory, prefering a particular micro-climate will be most susceptible to the effects of climate change when compared to other endemics that are widespread across the Ghats. In the case of restricted endemics such as the Shortwing or the Black and Orange Flycatcher, the slightest alteration in habitats as a result of anthropogenic activities or global climate change will lead to severe declines in populations. Therefore these birds can help serve as indicators for the health of an ecosystem.

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Black and Orange Flycatcher

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Ultramarine Flycatcher- another endemic from the Ghats.


Certain birds such as the Shortwing and the Broad tailed Grassbird can be found only in certain locations in the Ghats such as Grasshils in Ooty, the Avalanche hills, Peppara hills, and a handfull of other sites. With such varying levels of endemism, it is possible to determine the effect of habitat fragmentation, climate change as well as indirect effects of human presence in these previously untouched areas of the Ghats. The level of endemism exhibited by a species also helps to understand the specialist nature of its habitat preference as well as to create a map of the endemic birds and their exact distributional ranges in the Ghats. Current efforts are on to create a map of the various populations of endemics which would provide an exact picture of the level of endemism being exhibited by various species as well the size and distribution of specific populations.


Among the endemic birds, some such as the Malabar Grey Hornbill, Malabar Parakeet, Heart Spotted Woodpecker, etc can be found distributed across a wide area in the Ghats with populations from Tirunelvelli in the south to Bhigwan in the north, successfully being able to colonize the landscapes across the three major geographical gaps (see Mind The Gap). While some species have been unsuccessful in dispersing across these gaps owing to the specialist nature of their habitat preferences. 



Heart SPotted Woodpecker (L) and Malabar Grey Hornbill(R)
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Endemism therefore it would seem is important to determine the effects of habitat modifications, adaptations, distributional patterns, etc that may be influenced due to anthropogenic pressures or due to climate change events. It is after all a criteria for evolution, and if 'survival of the fittest' doesn't go in favor of these birds, we can very well say goodbye to some spectacular winged jewels of the hills.



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