Identification Guide to European Non-Passerines. BTO Guide 24. By Kevin Baker. British Trust for Ornithology, Thetford, 1993. 332 pages; 170 line-drawings. ISBN 0-903793-18-0. £15.00. This book has been designed for bird-ringers, but it is highly relevant for field ornithologists as well. Indeed, everyone interested in birds should buy a copy. Correct identification is essential for ornithological studies, and the BTO is to be congratulated on the publication of another landmark guide, albeit 16 years after the wader guide. The introductory section gives an excellent explanation of ageing and sexing techniques. Modern optical equipment gives the opportunity for field ornithologists to use much more detailed plumage characteristics for identification than was previously realised. Being able to identify the age and sex of the birds that you are watching can add considerable value to your observations. It is also good training for the identification of unfamiliar species and subspecies. Kevin Baker's carefully written text and detailed illustrations are easy to use. Each family has an introduction, giving the basic details of feather structure, moult, and so on. The species accounts then give criteria for differentiating between the sexes and between juvenile and adult plumages. For some species, recognisable differences have been established for more age classes. Inevitably, comparisons will be made with Svensson's passerine guide, and there will be disappointment because this non-passerine guide makes no attempt to be comprehensive. It is more bulky, but with less information. The spacious layout may be useful for margin notes, but perhaps more thought could have been given to keeping what is essentially a field guide as small as possible.