Winging it overseas

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By 2017-08-13

By Darshana Ashoka Kumara
Ceylon Today Features

Bird migration is a phenomenon nothing short of a miracle as some birds fly thousands of kilometres on their flyways to find the best environmental habitats. Historically, avian migration has been documented in literature in so far as three millennia back and even by some ancient authors like Homer and Aristotle. Around 1,800 of the 10,000 bird species living on the planet are considered to be migrant species.

"Some birds travel from the Antarctic Circle to the Arctic Circle. This is due to different reasons like fluctuation of water levels, climatic changes, availability of food and so forth. Some birds like the Bar-Tailed Godwit, a large wader in the family Scolopacidae, come to Sri Lanka on the way down from Alaska." Senior Lecturer of the Department of Zoology and Environment Sciences of the University of Colombo, Dr. Sampath S. Seneviratne, told Ceylon Today. Dr. Seneviratne is the Secretary of the Field Ornithology Group of Sri Lanka as well.

The Field Ornithology Group is the Sri Lankan partner of Bird Life International, the biggest bird conservator in the globe and the pioneer in declaring Important Bird Areas. The Field Ornithology Group of Sri Lanka is engaged in field studies country-wide focusing on bird biology. They carry out a special programme called 'Migrant Watch' in Baddagana, Thalawathugoda, Thalangama, Aththidiya and so forth and so on to study migrating birds.

Sri Lanka, a country where avifaunal diversity is highly rich, is home to around 500 species of birds with 250 being resident and 200 migrant. Some occasional visitors or vagrants too, are seen in the country. The arrival of migratory birds relies on the air currents of the year. Bird migration is identified as one of the most colourful components of global biodiversity. By and large, Sri Lanka witnesses the most beautiful migratory birds from mid August each year.

Migratory birds primarily enter into the island from Kankasanthurai, Jaffna or the Western part of the country. But their departure is different. They depart from the island as large flocks from Kalpitiya and nearby areas every year and it is obviously a picturesque phenomenon.

"Birds migrate to Sri Lanka on three flyways; two of them are along the two edges of the Indian peninsula, the other flyway is from the Andaman Islands. The vast majority of birds come across Central Asia and East Asia. Those migratory birds usually stay in Sri Lanka for six months from August." Vice President of the Field Ornithology Group of Sri Lanka, Kusum Fernando told Ceylon Today.
When it comes to bird migration, most birds follow mountain ranges, coastlines, and some other features of geography to shun the barriers on their ways. An English Ornithologist Ian Newton, in his masterpiece The Migration Ecology of Birds also remarks that the routes migratory birds follow during forward and return are not the same. It is observed that some migratory birds pursue a clockwise path in their journey to their destination and return.

Birds migrate to evade difficult winter seasons in certain parts of the globe and make tropical countries like Sri Lanka their home; no wonder, their migration is genetically designed in accordance to their endogenous rhythm as migration is a regular seasonal movement. All birds follow the same route as their precursors did. Bird migration is primarily driven by the availability of food.

Some birds would not migrate if they had enough food to consume, for example, hummingbirds, among the smallest of birds, prefer not to travel far if they are ensured of enough amounts of food in the winter. According to Dr. Seneviratne, factors like experience, learning and environment play a role in shaping bird migration patterns.

"Migratory birds like the greater flamingo (Phoenicopterus roseus) come to some parts of the island to find their food. Most of the greater flamingo birds can be found in Jaffna, Mannar and Bundala. At the onset of the season, their colour is white. But gradually they become colourful as they eat urchins, snails, crustaceans, and so forth once they are in the country. They usually leave the island by March- April. By that time they are truly colourful." Kusum Fernando added.

Migratory birds are equipped with a perfect morphology, specific structural features and physiology for flying long distances. A medium-sized shorebird, the Red Knot (Calidris canutus), that breeds basically in the northern part of the globe, has one of the longest migration courses of any bird, travelling up to 16,000 kilometers twice a year and also visits Sri Lanka.

"99.9% of migratory birds come to Sri Lanka from the Northern latitudes. We don't have reports on bird migration from Australia.

Also, as a matter of fact migratory birds do not also breed in Sri Lanka. They go back to the northern parts of the globe for breeding as they enjoy sunlight for more than 15 hours during the season. " Dr. Seneviratne explained.

As Sri Lanka is a tropical country positioned at a significant avifaunal entity, at the tip of the Indian peninsula, some species of migrant birds discover flyways along the Central Asian and Indian plains. The other major flyway is along the North East Asian plains. Even some pelagic species also travel to Sri Lanka during the autumn-winter season.

"A vast majority of migratory birds start to visit Sri Lanka from the second half of August and they stay in the island for around half a year and then return to their native places. Breeding happens at their original places. We, the Field Ornithology Group of Sri Lanka, have initiated a bird ringing programme." Kusum Fernando said.

Bird ringing or bird banding is a process where a metal or plastic tag is attached to the leg or wings of a wild bird. In Sri Lanka, bird ringing is prohibited to the general public. But, the Field Ornithology Group of Sri Lanka is allowed to do bird ringing as they are replete with specific techniques and professional capabilities.

The Field Ornithology Group of Sri Lanka implements the programme of bird ringing in collaboration with the Department of Wildlife Conservation.

"This ringing process has been very successful in studying the movement of birds. We do it causing least harm to the birds. We put a code with a serial number on the band and even contact numbers and email addresses.

Sometimes we get telephone calls and emails from professional birders overseas. Bird ringing is really a low cost and effective method to study birds." Dr. Seneviratne highlighted.

During the season of bird migration, the Field Ornithology Group of Sri Lanka will hold public seminars at the Department of Zoology of the University of Colombo to educate the general public. The seminars will be conducted at 9.00 a.m. on the last Saturdays of every month from August during the season.

The Group will also arrange field trips to Thalawathugoda and several other areas to monitor and study migrant birds. The event has been witnessed by people from all walks of life; experts in Ornithology, laymen, school kids, diplomats and so forth in the past years.
(Pix courtesy by Janaka Bandara)



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