A comprehensive and stunningly illustrated guide to all the world's parrot species, it was praised by the association as a "substantial achievement". It came in ahead of The New Oxford Dictionary of English, and the Encyclopaedia of Arabic Literature, which were also on the shortlist.
The 580-page book describes all 350 parrots of the world, from budgerigars to the majestic cobalt-blue Spix's Macaw, probably the world's rarest bird - at last count down to a single individual in the Brazilian forest.
Five of the world's leading bird artists have painted the 1,500 images in the book and the text is the work of Mr Juniper, now Campaigns Director for Friends of the Earth in London, and Mr Parr, who now works for the American Bird Conservancy in Washington. They decided to write Parrots when both worked for Birdlife International, a conservation group.
'We realised there was a need for a reliable, clear and credible identification guide that could be used by customs officers as well as field workers," Mr Juniper said yesterday. "It would help enforce the controls on the trade in parrot species and establish what was going on in the wild."
Destruction of forest habitat and the illegal wild bird trade are threatening the survival of many parrot species. "They're incredibly engaging, but they're also symbolic of what is happening to the world," Mr Juniper said.
'Parrots, a Guide to the Parrots of the World', by Tony Juniper and Mike Parr, published by Pica Press, Robertsbridge, East Sussex, pounds 35