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Bviculture auD ZooloQical ZTbeorv?. 



By D. Dewar, I.C.S., F.Z.S. 



It seems to me that aviculturists have not rendered 

 to zoological theory that service which might have 

 been expected of them in view of the exceptional 

 opportunities they enjoy of becoming acquainted with 

 the vie hitinie of birds. 



This is possibly because many of them are prac- 

 tical men and women, who care but little for theory 

 and so have not taken the trouble to acquaint them- 

 selves with the matters round which controversy rages. 

 It is in tlie hope of elucidating information which will 

 throw light on some of the zoological problems of the 

 day that I pen these lines. 



In the first place what is it that determines the 

 colours of birds' eggs ? The commonly-accepted theory 

 appears to be that birds' eggs are protectively coloured, 

 so coloured as to render them inconspicuous when 

 in the nest. This theory is fully set forth by A. R. 

 Wallace in his Darwhiisrn. As I have already pointed 

 out in Vol. XV. of \.\\^ Journal of the Bombay Nahiral 

 History Society this theory seems untenable when 

 applied to eggs that are laid in open nests. Birds 

 which construct such nests rely for the protection of 

 their eggs either on pugnacity and watchfulness or on 

 the concealment or inaccessibility of the nest. When 

 once a nest has been discovered by an egg-eating 

 animal no amount of protective colouring will save 

 from destruction the eggs it contains. 



The reasons why I believe that eggs laid in open 

 nests are not protectively coloured may be briefly 

 summed up as follows : — 



I. Allied species of birds, even though their nest- 



