One of the innovations in the Cage Birds marquee in recent years has been the demonstration aviaries.

It's a feature which introduces many different species of birds to visitors and has been very popular.

This year there are expected to be more varieties than ever on show.

Watch out for parrots, budgies, canaries - even blackbirds and song thrushes. These are not birds caught from the wild but bred in captivity. With so many species now endangered in this country and around the world, people who keep birds have a vital conservation role to play.