Preface 



THIS STUDY OF THE PARASITIC WEAVERBiRDS is an entity in itself, 

 complete as far as available data permit. It is also a part of a 

 general survey of the problem of avian brood parasitism, in the course 

 of which, besides many pertinent short papers, monogi^aphs dealing 

 with other families of parasitic birds were issued by me on the cow- 

 birds (1929), on the African cuckoos (1946), and on the honey-guides 

 (1955). To complete the series I hope eventually to publish a com- 

 prehensive comparative and interpretive summation of the biological 

 aspects of the subject. 



For many years I hesitated to write the present portion of the 

 survey because the available information was fragmentary, and there 

 was little reason to expect that the accounts resulting from this in- 

 formation would lend themselves to clarifying comment. Although 

 new information has been exceedingly slow in coming into print and 

 our present knowledge is still obviously fragmentary, now, after 35 

 years of patiently watching for such items in the literature, and of 

 extensive correspondence with resident observers in the homelands of 

 the bh'ds involved, in addition to personal field work in Africa, I ven- 

 ture to present the picture, incomplete to be sure, but sufficiently 

 filled in to reveal in general outline the nature of brood parasitism in 

 the weaverbirds. 



In the first part of this study is presented the evolution of brood 

 parasitism, and in the second the data on which I have based my in- 

 terpretation. The study should, I hope, stimulate observers to 

 supply further data and at the same time expedite their work by 

 directing them to the gaps that I have not been able to close. 



During the course of my studies, many persons and organizations 

 have assisted me in many ways, all of which contributed to the degree 

 of completeness attained in the following pages. Not that I consider 

 the problems fully worked out or the solutions arrived at as definitive, 

 but I would not have been able to come as far as I have without 

 these contributions. My personal field work in southern and eastern 

 Africa was supported first, in 1924-25, by the National Research 

 Council tlu-ough funds supplied bj^ the Rockefeller Foundation, and 

 later, in 1950-51, by grants from tlio John Shnon Guggenheim Memo- 

 rial Foundation, the American Philosophical Society, and the Smith- 

 sonian Institution. Without the generous support of tlicse sponsoring 

 groups the field work would not have been possible, and the study 

 would not have been undertaken. 



