Wednesday, July 21, 2010

The Cory's shearwater

The Cory's Shearwater is a large seabird that breeds mainly on islands and cliffs in the Mediterranean. 

In the Maltese Islands it breeds along most of the cliffs of Malta, Gozo and Comino as well as on the islet of Filfla. The nest which is not more than a shallow depression in the ground is usually found in deep crevices or underneath boulders safe from predators especially gulls.

In Maltese the Cory’s shearwater is known as ċiefa. About 7,000 breeding pairs are found in the Maltese islands. The largest colony is found at Ta’ Ċenċ on Gozo where it is estimated there are about 1,000 pairs breed but if you visit this site of any of the other colonies during the day you will not see any shearwaters flying around. 

Shearwaters which are not incubating spend the day feeding far out at sea. They return to take over brooding duties or to feed the young at night when the colonies become alive with loud calls like that of crying babies.

Cory’s shearwaters are at their colonies from late February to October.

 They lay a single egg at the end of May. The hatchling is fed on regurgitated food and the young bird grows and becomes fat very quickly. In August and September, while still covered in downy feathers, it weighs twice as much as its parents. In September it starts to grow true feathers. 

By this time it is visited by its parents less and less often and is abandoned completely for several weeks at the end of the breeding season. 

During this time it relies on the fat that was accumulated in its body while it was growing. 

In October the young birds have grown their full compliment of adult feathers and as their fat reserves are used up they start getting restless often visiting the opening of the crevice in which they were hatched until one night they open their wings and jump off to take their first flight. 

The colonies are deserted by the third week of October.

One hundred and fifty years ago Cory’s shearwater were shot to be roasted and mashed into a paste which was used as fishing bait. They were also available for sale at the Valletta market. Some hunters used to go out in boats to shoot them for fun. This practice increased in the 1980s when hunting from boats started to become popular even though by this time it had become illegal to shoot at these birds. Today the biggest threat is from human disturbance. 

These birds are very sensitive to light and abandon their colonies if there is too much light in the vicinity. To protect these birds it is important to ensure that no development that could be detrimental to this species is allowed along the cliff faces where they breed. Colonies are also destroyed by quarrying and no development along the cliffs where they breed.

This article appeared in The Times 21.07.2010

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