Cyprus Mail, Cyprus – Sep 30, 2014
By Jane Stylianou
The amazing movement of birds around the globe has fascinated people for centuries
BIRD MIGRATION has fascinated people for centuries. No humans can equal the movements of some birds on migration. For example, no human population moves each year as far as the Arctic Tern (Sterna paradisaea) which breeds in the Arctic and winters in the Antarctic, travelling between the poles twice a year.
As long ago as Old Testament times, people were aware that some birds came and went according to the seasons. The best evidence can be found in this quote from the book of Jeremiah: ‘Yea, the stork in the heaven knoweth her appointed times; and the swallow and the crane observe the time of their coming.’ It also appears that migratory quails provided food for the Israelites as they wandered in the Sinai desert.
Both ancient Greek and Roman writers commented on the movement of birds. Homer described the Trojan army as being like ‘cranes fleeing from the coming winter and sudden rains’. Aristotle was one of the first writers to make a serious attempt to explain migration: he realised that some birds remained throughout the winter while others moved south.
Aristotle may have been observant, even noticing that birds put on weight before setting off on migration, but he didn’t quite get it all right. He seemed to believe that some birds turned into others – for example redstarts (Phoenicurus phoenicurus) became robins (Erithacus rubecula) in the winter. His belief that swallows (Hirundo rustica) hibernated during the colder months was still a common explanation for their disappearance in autumn right up to the nineteenth century. The fact that they were often seen over water as autumn approached led to this theory. It was believed that the birds congregated on reeds until finally their accumulated weight bent them into the water, submerging the birds, which then settled for a long winter’s (underwater!) nap. To support this, it was claimed that fishermen sometimes found swallows in their fishing nets.
Even where it was accepted that large birds such as storks and cranes moved between continents it was not believed that small birds could do so. Another theory was that the larger species carried smaller birds such as warblers and thrushes on their backs. Native Americans believed that geese carried tiny hummingbirds in this way.
Eventually, such myths were dispelled and it was shown that all kinds of birds could make huge journeys in search of the right conditions to ensure the correct food supplies at all times of the year. As bird specimens were collected for museums, the general patterns became known. The places where swallows were shot in Europe and Africa showed the progression of their journeys. However it was not until birds were marked in an individually identifiable way that exact patterns were revealed.
At the start of the twentieth century, a scientific programme of bird ringing was introduced. This began a worldwide ‘field experiment’ that is still in progress and expanding more than 100 years later. This system of marking an individual bird has made a great contribution to clarifying facts about migration. Over 200 million individual birds have been ringed worldwide, helping to reveal a network of migration routes encompassing the globe used annually by over 50 billion birds.
Ringing can only be carried out by certified, trained and licensed ‘ringers’. They usually work at places where lots of migrants pass, and use nets with a very fine mesh, which they set up between bushes to catch the passing birds. Unlike their illegal Cyprus counterparts the bird-trappers, ringers employ skill and experience to ensure that the birds are not harmed or distressed. They are untangled from the nets carefully, identified and a small number-bearing, aluminium-alloy ring is fitted onto one leg. There are different sized rings for different birds. Each number is unique, showing where and when the bird was found. Before the bird is released it is measured and details about its size, weight and age are recorded. The rings are lightweight and have no adverse effect on the birds. This means that when a ringed bird is re-trapped or found dead it can be identified.
A ringing scheme has operated here in Cyprus for many years. Hundreds of birds are usually ringed each year – ranging from birds of prey to warblers. Local populations of some birds e.g House Martins (Delichon urbica), Cyprus Warblers (Sylvia melanothorax) and Sardinian Warblers (Sylvia melanocephala) have also been ringed to help with population studies. Birds ringed in other countries have been recovered here. In 2014, a Bee-eater (Merops apiaster) ringed in Israel was discovered, as was a Barn Swallow from Finland and several warblers ringed in Hungary.
Ringing shows that most of the migrants that pass through Cyprus spend the summer in central and eastern Europe, some reaching as far as Finland. Many scientists feel that as ringing relies on the unlikely event of a bird being either re-caught or found dead, its usefulness will be superseded by other methods such as satellite or radar tracking. Yet ringing undoubtedly still has a role to play in aiding scientists solve such mysteries as how birds find their way and how they know when to time their migration.
n If you want to know more about Cyprus’ birds or are interested in joining BirdLife Cyprus please contact P.O. Box 28076, 2090 Nicosia, telephone 22455072 or e-mail birdlifecy@cytanet.com.cy
In addition join us over the weekend of 6th and 7th October at events for Eurobirdwatch. These include a display of bird ringing; also for a walk at Phassouri reed beds on 21st October. Call 99059541 for details.
Copyright © Cyprus Mail 2014
