PILOTS are being reminded that aircraft and birds do not mix as a new measure is introduced to protect fledglings.

Crews are being instructed to fly higher to help ensure a noise exclusion zone around Thorp Perrow Arboretum, between Bedale and Masham, where birds of prey breed chicks worth thousands of pounds to conservation.

The tranquillity of the 85-acre woodland visitor attraction will be improved by the introduction of a minimum 1,000ft flight path with the backing of the National Aeronautical Information Service.

The measure covers civil machines as well as military aircraft from RAF bases at Leeming and Linton on Ouse.

The bird of prey centre at Thorp Perrow is the leading hatchery in Britain for the export of hunting hawks and falcons, but staff have found that eggs have often been broken by hen birds suddenly alarmed by a low-flying jet.

Chicks sent to clients in Africa, India, America and elsewhere are each worth thousands of pounds. Early hatchings include three Lugger falcon chicks.

Centre director Tom Graham said: "Selling chicks helps us to fund the vital conservation work undertaken on behalf of the species looked after at Thorp Perrow."

The centre has more than 40 species of hawk, owl, kite, falcon, eagle, vulture, cara cara, kestrel and buzzard.

Sir John Ropner, owner of the arboretum founded by his father almost 80 years ago, said: "We are very grateful to the flying authorities. They are helping immeasurably to guarantee the peace and calm which our 40,000 annual visitors expect to find and enjoy.