MINISTERS were warned by their own advisers that a plan to trap and move sparrowhawks to stop them killing racing pigeons would be expensive, ineffective and illegal, the Sunday Herald can reveal.

The birds of prey have a strong homing instinct, so would probably find their way back to the pigeon lofts from near which they had been removed, advisers said. And if they didn't, other sparrowhawks would simply move in and prey on the pigeons.

Despite this, the environment minis-ter, Michael Russell, has ordered a revamped experiment this winter to move sparrowhawks away from pigeon lofts. Though this is regretted by environmentalists, it has been welcomed by pigeon fanciers.

Russell had originally planned a sparrowhawk relocation trial in March, but postponed it at the last minute because delays meant it would interfere with the birds' breeding season.

Now he has instructed the government's wildlife agency, Scottish Natural Heritage (SNH), to work with the Scottish Homing Union (SHO), representing Scotland's 3500 pigeon fanciers. The two organisations are discussing beginning a trial in November, covering over 40 pigeon lofts.

But when Russell first proposed a relocation trial last winter, his plan was strongly criticised by his official advisers. Documents released under freedom of information legislation show that the Scottish government's chief ecological adviser, Dr Ian Bainbridge, had serious doubts.

Bainbridge pointed to evidence suggesting that birds of prey were "remarkably capable" of finding their way back to their home territories. "So I think in many cases, relocation may not work," he said. "This is not a productive route to follow."

In an email to the government, SNH's senior policy and advice manager, Professor Des Thompson, pointed out that removing sparrowhawks could cause more to move in, and actually increase predation on pigeons.

"Legally, our advice is that there is no basis for translocation because the purpose is to protect private property, and other legal, non-lethal methods have not already been tried," Thompson cautioned.

He warned that a trial would be "extremely expensive", costing "several hundred thousand pounds". Both Bainbridge and Thompson also argued that sparrowhawks were likely to suffer damage to their feathers if they were trapped.

The Royal Society for the Protection of Birds (RSPB) agreed with the government's advisers. "Less than 1% of released racing pigeons are taken by sparrowhawks," said RSPB Scotland's Duncan Orr-Ewing. "We regret the decision to proceed with this trial."

Concerns about the sparrowhawks' welfare were echoed by the Scottish Society for the Prevention of Cruelty to Animals (SSPCA). "Sparrowhawks are notorious for injuring themselves when they are trapped," said the society's chief superintendent, Mike Flynn.

But Linda Brooks, the secretary of the Scottish Homing Union, was "delighted" that the relocation trial was going ahead. "How could anybody say it will be ineffective when they haven't done the research?" she asked.

Seeing sparrowhawks prey on pigeons was "totally devastating" for owners, she said. "It takes about 20 minutes to kill a pigeon and it can be horrific."

SNH's head of policy and advice, Professor Colin Galbraith, also sounded supportive of the forthcoming trial. "I'm now comfortable that we've got a robust trial in the making that will give us some insight into this issue," he said.

According to the Scottish government, the new trial would comply with legal requirements. It was "sensible and justifiable" to explore non-lethal methods of protecting racing pigeons from sparrowhawks, argued a government spokesman.

"We are currently working up a more fully developed version of the project, and we would want to involve the widest group of stakeholders to assist the Scottish Homing Union with their genuine problem," he added.

"It should however be stressed that this project will be run on a trial basis. Its effectiveness will be fully assessed before it is taken any further."