WHAT goes up must come down - but not in the case of Jack the falcon, which decided to break with falconry tradition and stay in the sky.

It was a routine part of falconer Rob Allott's act, sending his pair of lanner falcons, Jack and Jill, into the air so they could swoop low above the heads of the crowd at Lanchester Show at the weekend. But while Jill came tumbling down, Jack did not.

Now Jack's owner is offering a £500 reward for the return of his prized bird, which he has looked after for seven years.

Mr Allott, who runs the Prince Bishops Bird of Prey and Falconry, in Belmont, Durham, said: "I'm offering this reward because this bird is priceless, but only to me.

"Anyone who has seen Jack and Jill performing will know why he has a big reward on his head. It takes years to train a bird to this standard.

"It feels as if there's been a death in the family."

Jack and Jill's acrobatics form the centrepiece of Mr Allott's show, which he performs on horseback dressed in costume to recreate a medieval hunting scene.

Jill has already begun to pine for Jack, as the two birds fly together at every show.

Mr Allott thinks the falcon may have found a thermal of warm air, used by birds of prey to glide for up to 30 miles.

Attached to Jack is a tracking device with a 30-mile radius, but even when Mr Allott took the receiver to the top of Durham Cathedral to get the best possible reading, it has produced no results.

Jack does not know how to hunt and Mr Allott fears the falcon may be weak with hunger, or may start dive-bombing people in the hope of being handed food.

The bird is ringed and should still have its silver transmitter and red cap. Anyone who spots him is asked to contact Mr Allott on 0191-384 8498.