SCOTLAND’S politicians reckoned without Prudence when they spent thousands of pounds making Holyrood pigeon-proof.

The enterprising bird ignored the spikes lining every possible ledge of the parliamentary palace in Edinburgh to build her nest right over the front door.

After repeated efforts to make the £431 million building poop-free, Members of the Scottish Parliament were understandably miffed when the hallowed walls were desecrated from above. They were even more upset when they learnt that it would cost £250 per bird to remove Prudence and her fledgeling, Polly.

“For £250 I will personally wring its neck myself,” declared Margo Macdonald, the independent MSP already vociferously critical of the cost of the building.

So dismayed are officials that they have organised a constant vigil to ensure visitors to the building are protected from what has been delicately referred to as “pigeon debris”.

The persistence shown by the feral pigeons (Columba livia) has prompted a series of meetings on what to do about them. Options range from shooting them, scaring them away or trapping and taking them to be cared for at a bird sanctuary 100 miles from Holyrood.

Ecolab, a company engaged by the Parliament for “pigeon-related advice”, has won the anti-pigeon contract but advises leaving the birds in peace until Polly flies the nest. While the adult bird would be perfectly able to cope if scared away from the building, the fledgeling might not be if it were to be separated from its mother. A parliamentary spokeswoman said that unless new problems arose, the birds would be left alone. “We would prefer that nature takes its course,” she said.

The approach was welcomed by animal welfare groups. Ross Minett, of Advocates for Animals, said: “It is very hard to put a price on any animal’s head. We believe the general public would be supportive to these animals being taken to a wildlife centre rather than killed unnecessarily.”

Prudence and Polly were discovered on the roof over the public entrance by building managers who had hoped the introduction of spikes would keep away feral pigeons, defined as a pest species in legislation.

Spikes are used widely as a relatively cheap and easily installed measure to discourage pigeons from sitting on roofs, ledges and windowsills.

They are not, however, foolproof, and despite their reputation for being bird-brained, pigeons have shown ingenuity and determination in overcoming them. They have been known to cover the spikes with twigs and straw so that they can perch comfortably.

The birds use ledges on buildings as vantage points to spy food and are frequently found overlooking the entrances to fast-food outlets.

For roosting and nesting they prefer more sheltered spots, such as under the eaves of buildings where they are protected from predatory species and human interference. Such sites also offer warmth and shelter from the rain.

Feral pigeons, descended from domesticated rock doves, are notoriously difficult to clear from an area, said Martin Benson, of First Response Environmental Services, one of Britain’s biggest pest controllers.

Spikes, he said, were only a deterrent: “They can squeeze through if they really want to. That may be what happened in Holyrood.”

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Donor organ allowed child’s own heart to heal
• Michael Jackson: Not the final chapter
• Brüno toned down for 15 rating