We are in a golden age for the study of brood parasitism, judging from both the quantity and quality of recent scientific publications on cuckoos, cowbirds and parasitic finches by investigators working in Europe, the Americas, Africa and Asia. As Johnsgard (1997) remarks in his preface, the evolutionary, ecological, and behavioural questions posed by obligate brood parasites are among the most intriguing contemporary ornithological topics. Rothstein & Robinson (1998) explain that brood parasites make ideal subjects for testing the generality of models for the evolution of social and mating behaviour, foraging behaviour, spatial distribution, and vocal development, because the strategy of providing no parental care removes constraints imposed on other birds. Since Aristotle, people have been fascinated by brood parasites, but only in the past two decades has the number of investigators working on this topic reached a critical mass and created momentum that promises many breakthroughs. New studies are being completed so rapidly that a general book is inevitably out of date on some topics by the time it is published. A complete library on brood parasitism should add two recent volumes (Morrison et al. 1999; Smith et al., in press).to the three reviewed here.
