project highlights

White-bellied shortwing

The White-bellied Shortwing is an endemic, threatened, understorey bird that is found in the Shola forests. It is is a small bird, about 25 gm, and difficult to see as it spends most of its time within 2m of the ground in the forested parts of the Shola habitat. It is also very cryptic except in the breeding season when its characteristic song makes it easy to locate.


It is one of the five Shortwings in the world, and the other species are found in North East India and South-East Asia. The Shortwing in southern India has been split into two species (pictures above) that appear different in plumage. Apart from scant sighting records, there was very little information on the species when we started this project.


The Shortwing is an understorey bird, and such species are known to be very sensitive to habitat disturbance as they are often inflexibly adapted to micro-climatic conditions. They are also known to avoid edges and avoid crossing inhospitable habitats. The Shortwing is also the only endemic bird species exclusively found in this habitat but found along the length of the “Sky-island” complex of the Western Ghats. Studying the Shortwing provides insights into how species cope with the patchiness and isolation of Shola forests. It will also provide valuable information on an endemic, threatened bird’s biology that can be used for its conservation.

general information About the species

White-bellied shortwing research

Kalyan Varma

Clement Francis

 
 
distribution

The first objective of the project was to understand the species’ distribution. With very few sighting records at that time, we undertook a survey, sampling 553Km of trails in six National Parks, 14 Wildlife Sanctuaries, four Tiger Reserves and 12 Forest Reserves in four southern states - Kerala, Tamilnadu, Karnataka and Goa. We found that the species is a high elevation specialist, found only in the Shola forests above 1400m. In regions from 1000m to 1400m, the species may be found in low densities. In high density areas, it is often found in forest patches fragmented and separated from other patches. It is also found on all the ‘islands’ of the sky-island system.

Published materials (peer reviewed): Tamil Nadu & Kerala, Karnataka and Goa

News articles: Deccan Herald June17’08, Deccan Herald June27’08 (funny interview - translation from regional language)

 
 
phylogeography

From the understanding that the Shortwing is found on isolated ‘islands’ stemmed the desire to examine the connectedness between the different ‘islands’, colonization patterns and the effect of habitat fragmentation on population structure. We sampled almost all populations of Shortwings from three different states of India. Results using mitochondrial DNA reveal that major divisions in the population of the species reflected the locations of geographical gaps in the Western Ghats rather than the ‘island’ structure. The physiography, in conjunction with paleo-climate of this region historically resulted in multiple glacial refugia, which, in turn, appears to have determined the evolutionary history and current population structure of the species. We are still in the process of examining effects of fragmentation using microsatellite markers that have just been standardized.

Published materials: Evolution and phylogeography

Popular version of phylogeography work

News articles: The Hindu 15Oct’10, Nature India 15Oct’10, The Hindu 16Oct’10, Times of India 18Oct’10, MailToday 19Oct’10, The Telegraph 25Oct’10, The Free Library

 

population biology

 

insect community 

 

disturbance & socio-economics

 

P.R.Shankar

Dilip Venugopal

V.V. Robin

R. Nandini.

R. Nandini

Kalyan Varma

Emeline Vitte

V.V. Robin

V.V. Robin

Song variation

Bird song is known to vary between individuals, populations and species and we proposed to test this with the Shortwing across genetically most different and similar populations across ‘sky-islands’. We found that songs could be statistically assigned to specific populations, while individuals showed considerable plasticity in song types they sang. While songs across genetically different populations were most different, populations separated by deforested lands were also different in song. We are in the process of examining song syntax for cultural transmission of song types between geographically isolated but genetically similar populations.

Published materials: Song variation across two islands

 

S. Ramakrishnan

Given that the Shortwing is an insectivorous, terrestrial bird, we wanted to examine whether arthropod abundance was correlated with Shortwing presence and abundance. Unfortunately direct observations of Shortwing foraging was not possible (though they were colour banded for this) due to their cryptic behaviour. Analysis of the arthropod community in different study plots and control plots showed that certain orders and size classes characterised the high Shortwing density plots. Though this fails to establish cause and effect with the arthropod community, it does provide some information about where to start looking for an in-depth foraging study. 

In an intensive study area in the Anamalais, I established a network of plots along a disturbance gradient. Four 2.5 ha plots in a forest patch (>2500 ha) and close to this, four small patches (<1ha) where we expected a source-sink metapopulation dynamic to be operating. With five years of sampling and 130 individuals captured in a mark-recapture framework, we now have some information on the species. Shortwings are found in nearly the same density in disturbed and undisturbed habitats, however the survival rate in the disturbed habitats is very low. There were hardly any source-sink movements during this study period, though there was one local extinction in a small patch that was subsequently colonized.


Published materials: Determining differences in sexes of Shortwings

Habitat disturbance affects Shortwings in many ways but the causes of disturbances were not addressed. The major source of disturbance in our study area was subsistence firewood collection by labourers employed in tea estates adjoining Shola forests. With some colleagues we conducted a socio-economic survey of 450 households examining sources of fuel and patterns of usage. We found that houses with both husband and wife employed as permanent workers used mostly LPG and very little firewood, while households with temporary workers used mostly firewood as its major fuel source. Some families used up to one tonne of firewood per month, all of it coming from rain forests. Interestingly, most of the respondents expressed a desire to use alternate fuel sources and were even willing to pay for this resource. We believe that the solution to this problem lies in bringing together all the stake holders - forest department, tea estates, the workers and conservation biologists.