RETURN OF THE MIGRANTS
de Silva Wijeyeratne, G. (2003). Return of the Migrants. LMD. December 2003. Page 220. Volume 10, Issue 05. ISSN 1391-135X.
Gehan goes in search of migrants and discovers some rare birds closer to Colombo.
Gehan de Silva Wijeyeratne goes in search of migrant birds
Darkness had enveloped the Golf Course. On and off, the melancholy crescendo of a Stone Curlew filled the air. Red-wattled Lapwings twittered nervously. Perhaps a cat or mongoose or some other nocturnal predator was on the prowl. A flock of birds took off uttering a soft, piping call. I recognised them as Black-winged Stilts. This heralded to me in no uncertain terms that the migratory birds were arriving back in force.
This is something I had been aware for a number of weeks. Flock after flock of Blue-tailed Bee-eaters had been seen swooping across the air space over Colombo. Some were on their way further south or into the center of the country. Some had taken up residence in Colombo. Barn Swallows were also a part of the new aerial scene as they swooped about, catching insects in the air. In Nawam Mawatha, I had watched a flock sallying in the air and dashing adroitly between office buildings. Passers by wondered what I was looking up at. Usually drab TV antennas, now sported a colourful Bee-eater or two. I had even caught a snippet of the shrill call of a migratory Brown Flycatcher. These migrants which I had observed so far, were are all birds which are called Passerines or Perching Birds.
The Black-winged Stilt were different. They belonged to a group of birds known as waders. What is it about waders which gets birdwatchers so excited is hard to explain. On first appearances they are drab, lack the fine songs of many forest birds and are arguably un-inspiring. But waders are a big draw with birdwatchers. One reason is that they are difficult. Any beginner will show exasperation at a field guide’s plate which shows half a dozen wader species, all looking remarkably the same. Here lies their appeal. Just as Golf is a game against oneself, wader watching exercises those parts of the grey matter which other birds fail to reach. They are an intellectual test in a recreational pursuit which is largely one of aesthetics. The habitats in which waders are found also may be a clue to their appeal. They are usually found in lagoons, mud flats and coastal areas, which are often wild and forlorn. Theses sites require a sense of adventure to reach and poetic sensibilities to appreciate the romance of their setting.
Waders also exemplify one of the marvels of the biological world, migration. Most images of migration are synonymous with large flocks of waders arriving on our mudflats. Hearing the calls of the Black-winged Stilts prompted me to visit Talangama, on the outskirts of Colombo the following evening, in search of more waders. I was right, as expected, on a muddy, ploughed paddy field I came across a flock of ten or more Wood Sandpipers and about five Black-winged Stilts. The Stilts, are according to the text books, resident birds. They are found throughout the year in the dry zone. But keen birdwatchers including myself have noticed that mysteriously, Stilts appear in the wet zone, during the migratory season. They are often in the company of other migratory waders. Are they part of a local movement or are our resident Stilts boosted by a migratory influx? I suspect the latter. In fact I suspect many other species which are considered resident are joined by a migratory population.
A case in point was a flock of fifty or more Pheasant-tailed Jacanas I observed at Talangama, that same evening, in the second week of October. They were also with Wood Sandpipers and tightly bunched up. But in the preceding months, I hardly saw a Jacana in Talangama and now, there were so many. Perhaps these Jacanas had moved down from the north central province or perhaps they were part of a contingent from further afield.
It is both sad and disappointing that so little remains known about Sri Lankan birds. With respect to the migrant birds, much work is being done overseas through Bird Ringing studies. A metal or plastic ring, extremely lightweight, is attached to the leg of a bird. When a bird is re-captured at another site, scientists are able to determine the international movements of a species. They also take various morphometric measurements to understand the bio-physics of migration. Charting the movement of migratory birds is no easy task. Literally several hundred thousand birds, over a number of years have to be ringed by hundreds of volunteers and professional scientists. It is only then a sufficient number of birds is likely to be re-captured or a ring recovered from a dead bird. The statistical likelihood of a particular bird ringed in Sri Lanka being re-captured in Central Asia for example, is very small. It is like for the proverbial needle in a hay stack. This has fortunately not deterred scientists who continue to persevere and ring the several thousand birds which are necessary to collect adequate data to build up a picture.
In Sri Lanka, a proposal has been submitted for a collaboration between the Department of Wildlife Conservations, the Field Ornithology Group of Sri Lanka with support from the Jetwing Research Initiative to embark on a National Bird Ringing Program. If the program receives the go ahead to set up a number of field stations to conduct year round bird ringing, meaningful results can be obtained.
Bird Ringing can also be used to study the winter territoriality of birds. By using a sequence of colour rings, it becomes possible to establish whether the same individual is showing what biologists term ‘site fidelity’. For example, every year, Indian Blue Robins, Pied Thrushes and Kashmir Flycatchers winter in Victoria Park in Nuwara Eliya. Are the same individuals returning to the same territories as last year? Colour ringing and identifying birds as individuals will help answer these questions. The same could apply to the Black Bitterns which appear every winter in numbers at Talangama and Bellanwila Attidiya.
Talangama is an important wetland habitat on the outskirts of Colombo. It value for flood detention and for aesthetics is beyond question. The seasonally harvested and ploughed paddy fields, is also a valuable wader habitat, for migrants passing through Colombo. Who would imagine that such a rich site for bird life exists so close to Colombo.
The writer is the CEO of a wildlife and adventure travel company. He is the lead author of A Birdwatcher’s Guide to Sri Lanka (OBC) and A Photographic Guide to the Birds of Sri Lanka (New Holland). To subscribe to his free, wildlife e-newsletter, e-mail him at firstname.lastname@example.org with “subscribe wildlife news” in the message header.