Thousands of invading birds culled

Four species had been on rapid rise in cities and environment specialists say 'they have a large impact on the environment and on native species'.

A rose-ringed parakeet is one of the four species of birds targeted by the Environment Agency - Abu Dhabi.

ABU DHABI // More than 100,000 birds have been trapped and culled in the capital in an effort to to reduce the populations of alien species, according to environment officials. The four birds targeted - the rock pigeon, house crow, common myna (also known as Indian myna) and rose-ringed parakeet - were not commonly found in the country until about two decades ago. They were attracted partly by the rapid development of cities.

Dr Maan al Hakim, environment specialist at the bio-security unit of the Environment Agency-Abu Dhabi (EAD), said the cull was necessary as the birds' numbers were increasing rapidly. "Their numbers rose so much that we had to control them," said Dr al Hakim, although he was not able to provide population figures. "These are pest birds. They are alien species, not native birds. They have a large impact on the environment and on native species."

About 100,000 rock pigeons, 5,000 mynas, 3,500 parakeets and 1,200 crows have been trapped and killed since February this year. Eight teams, of between eight and 10 people each, have been on 1,300 catching missions, setting up mobile traps around the emirate. Last month 25 permanent traps designed to catch myna birds were installed in Al Ain, said Dr al Hakim. Mynas and crows eat the chicks of the laughing dove - a local bird. But mynas also seem to be key to controlling another exotic newcomer - the superb starling, an African bird that can now be seen in some areas of Sharjah and Al Ain. With a lack of natural predators, the starlings are thriving, and compete with native birds for food.

Dr Reza Khan, director of Dubai Zoo and a bird specialist, agreed that the four culled species were recent arrivals. "Crows came here following two routes - from Kalba and from Hatta and then on to Al Ain," he said. "Back in 1989, when I was working in Al Ain, there were no crows there. Until 10 years ago, Abu Dhabi had no crow population." Mynas are natives of Sri Lanka, India and Indonesia, brought to the country - like the parakeets - by collectors and pet traders.

Rock pigeons, said Dr al Hakim, were brought here by ships coming from south-east Asia. "It is only a three-day trip from shore to shore," he said. The four species have since been thriving. "Their natural predators are absent here," said Dr Khan, explaining that falcons, eagles and larger owls are not present in large numbers. In addition, the predators prefer remote areas, whereas the invasive species are well adapted to city life, where food, greenery and water are freely available.

In a testament to how well adapted the new birds are to urban areas, Dubai Municipality has had to change the design of its lamp posts twice after parakeets and mynas began building nests inside them, causing damage. In 2000, the International Union for Conservation of Nature, one of the world's most reputed conservation organisations, included the Indian myna on a list of 100 of the world's worst invasive alien species.

While Dr Khan agreed that the newcomers had had a negative effect on some local species, he said the issue needed to be studied in detail before a decision was taken to eradicate populations. In addition, if the invasive birds were removed, this could free space for other animals well adapted to city life to move in - such as rats. He called for an expert committee to study the issue in detail and to monitor populations.

"When we realise what the negative impact is, it could be too late, like in Australia," he said. There, rabbits, goats, camels and other animals were introduced with catastrophic results. "Instead of taking immediate drastic action, people should study the impact in more detail," he said. "In the meantime, they can keep the populations under control instead of wiping them out completely." While Dr al Hakim defended the method used - gassing the birds with carbon dioxide - he said another gas should be added to the mix to put the birds to sleep first before suffocating them. But he did say that an effort to reduce the numbers was necessary.

"This is a man-made problem and it is up to men to fix it," he said. [e-mail]