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| Sunday, 18 April 2004 |
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Features |  |
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How do birds talk to one another? Vimukthi Fernando braves the mud and slush of Sinharaja to find out. The current study on Drongos could be the very first bird study on mimicry in the world.
Darkness enshrouded us, with rain pelting down. The headlights of the vehicle showed a small road leading uphill, covered with a muddy gush of water. "Is this the road? Unlikely" We had already lost our way once - a dead end in the forest. We decide to take the road uphill. The climb is hard and it seems eternity. The time is past 11.00 p.m. After what seems aeons, there is no sign of the Lodge. A flash of lightening. "There, a pipeline" my jubilant colleague points out. We move on. Finally, a concrete sign of life... Much calling and banging on the door... The face appears to be a little cross at the disturbance in the dead of the night. We are at Martin's Lodge at Sinharaja. We settle for a much needed rest, informed that the persons whom we are here to meet had already gone to their camp in the forest. We are here to meet three persons involved in observing the nesting behaviour of the Ashy-headed Laughing Thrush (Garrulax cinereifrons) an endemic bird found in Sinharaja forest. A shy bird limited to the wet lowland rainforest of the southwest portion of the country. Considered vulnerable due to the reduction of its habitat, the bird's nesting was observed by this team during December 24 to January 21, 2004. The first nest of the species was only found in 1984, after 132 years of its discovery. Waking up to the bird songs and the mist that covers the forest. We meet the team at their camp about a mile away from the Lodge. Eben Goodale from the University of Massachusetts, USA is conducting the study while Prasanjith Caldera an avid bird watcher and ex Naval Officer assists him as the Field Supervisor. Ashoka Jayaratne from Kudawa also assists and is involved in the study. However, the nesting behaviour of the Ashy-headed Laughing Thrush is only a "lucky coincidence" we learn. Their major study is on the vocal interactions of birds. In other words, how birds talk with each other!
Bird study in Sri Lanka especially in Sinharaja had been fascinating,
says Eben. For "you can find many species in a relatively small
geographical area, and you can observe them very easily." His
introduction to Sinharaja forest had been equally interesting. "Back
in 1995 as an undergraduate looking for a summer job. One day at college I
saw Prof. Peter Ashton, whom I had known as a renowned biologist leaving
the premises in his car. I ran there and asked "It is interesting how birds interact vocally. It is a nice way to look at the birds. We do not have many studies on bird-calls. But, the flocks run on bird-calls," explains Eben. His study, on inter specific communication in bird flocks enlightened him on how birds in a flock react to predators. During the study they observed actual hawks coming and attacking flocks. The study found that it was two species almost always included in the Sinharaja flocks, the Orange Billed Babbler and Greater Racket Tailed Drongo make most of the alarm calls. "However, it is the Drongo which makes more reliable alarm calls. There are some species who just watch. Species who talk and species who listen. The calls of different species relay different information for the flock. Some, like the Babbler call for anything. Others only chime in if there is a real attack on the flock," Eben explains showing us his predator bird models. We listen to the bird calls and songs they had taped and understand the differences between calls to gather the flock, alarm calls and bird songs.
It is time for lunch, and we join them in the "kitchen" to partake a meal with 3 curries. "It is special today," says Eben's wife and fellow researcher Iromie studying Sinharaja's topography. "If you were not here, we will have one curry. Everything cooked together." The afternoon is not for walking in the forest. For this time of the year (March to May) it starts raining early. We complete our interviews and return to the lodge. Early next morning, Prasanjith and Ashoka are ready to take over. Prasanjith a member of the Field Ornithology Group who had participated in the national bird ringing programs is in Sinharaja for the past 3 years, assisting Eben. "I was interested in nature from school days. However, it is Ex. Navy Commander Shedrick Martinstein who taught me much about nature and fuelled my love for nature. I am always grateful to him" he reminisces about the time in the North and East, where he was based as a naval officer, which gave him an opportunity to observe the migrant birds. Ashoka, a resident in Kudawa had been assisting different research teams from an early age of about 10 years. After his secondary education, he had decided to make employment out of his hobby. His knowledge on birds, keen eyes and alertness helped us to glimpse many a bird. On our way, after listening a few moments, "The flocks are still gathering," explains Prasanjith. After each bird call, Prasanjith and Ashoka tell us which bird it is, and we see many flying hither and thither. Those at the top layer of the forest. Those who thrive on the next layer. Those living on berries and nectar, and those that live on insects. We learn how the bird flocks are followed from grid to grid, in the forest. How bird calls are recorded, how they are counted and how they are ringed. It is dark inside the forest. We are warned of the venomous snakes, but meet none. However, leeches throng in to attack the team. Beauty lurks everywhere, along with danger. Blooms... purple, orange and blue... attract the eye. Rocks and caves tell a story by themselves. It offers great respite for the busy city dweller, the researcher and the villager alike. The news we heard from the villagers the previous day is disturbing. Politicians had already blocked out parts of Sinharaja for settlements. As we bid adieu to Sinharaja we feel a tinge of pain. "Would any of this be left for our children to enjoy?" my colleague asks. I keep mum. |
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Their current study is on the mimicry of Drongos, an essential member
in the Sinharaja flocks, explains Eben. It could be the very first bird
study on mimicry in the world. Meanwhile, it is the very first in Sri
Lanka. "I was interested in finding out why they mimic others?"
The question lead Eben to conduct a special study. Drongo a bird which
plays an important part in the flock is very good at mimicry he explains.
The Drongo mimics alarm calls of other birds and calls of predators. Alarm
calls of other birds are made "when Drongos are alone and out of the
flock, or when they are at the periphery of a flock to bring others
towards them. Calls of predators are mimicked to protect the young, when
they are at a tender age unable to defend. Drongo tries to shoo away its
predators," says Eben.
whether he had any summer
jobs expecting some paperwork somewhere. However, he asked me whether I
liked to go to Sri Lanka to assist a bird-study. I ended up assisting a
project, which studied the effects of logging on birds by Prof. Sarath
Kotagama at that time. The study included counting the flocks."
Enthralled by the forest and its many flocks of birds Eben came back again
and again. Got himself involved in studies conducted by Prof. Kotagama,
Prof. Ashton and later on, started conducting his own studies. In the year
1999, he studied the alarm calls of birds for his doctoral thesis.
