502 SCIENCE PROGRESS 



for the many extraordinary statements that are to be found in the text. 

 Possibly the most startling is that the cuckoo cannot call from the end of 

 June till its next mating season since it " loses its voice " for that period. 

 But many others, such as the assertion that the brown colour on the head 

 of the Black-headed Gull " fades away " in the autumn, leaving it entirely 

 white, are almost as surprising. 



Mr. Green's illustrations are delightful, particularly the monochrome 

 plates. 



The general get-up of the book is most pleasing. The remarkable price 

 of los. 6d. in these prohibitive days should ensure it a sale, and it will no 

 doubt do some good in the cause of bird protection, but its limited scope and 

 the fact that it is bristling with inaccuracies will prove a handicap. 



W. R. 



The Cuckoo's Secret. By Edgar Chance, M.B.O.U. [Pp. x + 237, with 

 frontispiece, 15 photographs, and 2 maps.] (London: Sidgwick & 

 Jackson, 1922. Price 7s. 6d.) 



The major portion of the book consists of a record of facts, the concluding 

 chapters are theoretical. The records cover four seasons of careful systematic 

 work, and are of the most extraordinary interest. Mr. Chance's film, which 

 enjoys the same title as his book, is now well known. It is one of the products 

 of his labours, and selected prints from it are included in the volume under 

 notice, as well as pictures taken with an ordinary camera. The points on 

 which the author lays chief emphasis are the following : A cuckoo may lay as 

 many as twenty-one eggs in a season, these being produced generally on every 

 second day, though a normal set, i.e. one laid without human interference, 

 is probably much smaller ; an individual cuckoo is not promiscuous in its 

 choice of fosterers, but prefers a given species (in this case the meadow pipit) ; 

 the bird actually lays its egg in the nest and not outside it, later to transfer 

 it thither by means of its beak or its throat ; the hen cuckoo owns a territory 

 in the same way as do the males of most other species. There are, in addition, 

 many minor points of interest. 



The limited space at our disposal prevents us from discussing the author's 

 theories expounded in the closing chapters. One cannot help thinking that 

 these might have differed considerably if looked at from some other standpoint. 

 Some, at least, fa^l to carry conviction. There seems to be no support in 

 the recorded observations for the theory that the cuckoo deliberately victimises 

 the same individual foster birds season after season. It is hard to believe 

 that the taking of the cuckoo's eggs as laid is a stimulus to the bird to continue 

 laying. The explanation offered for the fact that reddish eggs of the cuckoo 

 have been found in robins' nests, and bluish ones in the hedge sparrows', is 

 ambiguous, and if read in the way evidently intended, highly improbable. 



Stuart Baker in a recent paper {Bull. Brit. Ornith. Club, March 1922) has 

 made some interesting criticisms of some of Mr. Chance's other contentions, 

 their expressed views on some points being exactly opposed. 



It is a pity that after the author has emphasised his objections to the all 

 too frequent custom of generalising from limited observations he should himself 

 fall into the trap. He states in chapter xvi that " I am quite sure, from having 

 constantly kept a daily watch on cuckoos for the last four years, that the 

 hen cuckoo does not utter the ' cuck-00 ' note." The " daily watch on 

 cuckoos " consisted chiefly in watching a particular hen cuckoo, actually 

 not daily, but more generally every second day (laying day) for four seasons. 

 It is true that observations were made also on others, but these appear to 

 have been more casual, although these too were made mostly on laying days. 

 The author has evidently not had his attention called to the note in The 

 Countryside ioT 1914, by J, Whitaker, recording the case of a cuckoo shot in 

 the act of " cuck-ooing " which, on dissection, proved to be a female. 



