"Seabird Energetics" is a composite volume with a coherent theme. It makes a valuable contribution to our understanding of the costs of breeding, the significance of which goes far beyond physiology as a brief historical perspective may illustrate. After decades of mainly anecdotal observations by natu ralists with an interest in seabirds, there was still so little information that in 1954, David Lack in his book "The Natural Regulatiori of Animal Numbers" was forced to ignore seabirds in a way that would be unthinkable today. The late fifties, however, produced a seminal contribution to seabird ecology and behaviour in the series of papers which stemmed from the Centenary Expedi tion of the British Ornithologists' Union to Ascension Island. Not only had quantitative ecology become the norm but the interest aroused by the European Ethological approach to bird behaviour had led to properly descriptive and analytical studies of seabird behaviour. The complex interactions between social behaviour and ecology then received more attention and the sixties and seventies brought a flood of papers on ecology and on some social aspects of breeding ecology. V.C. Wynne-Edwards linked these two as part of his attempt to understand the mechanism of the regulation of animal populations in his book "Animal Dispersion in Relation to Social Behaviour" (1962). He paid considerable attention to seabirds and the phenomena of clutch and brood-size, deferred breeding, "rest" years, etc., although, unfortunately, the most relevant studies were yet to come.