1SS5J Allen on Sexual Selection and the Nesting of Birds. I ? I 



which both sexes are brightly coloured and which rear their 

 young in holes or covered nests." As British representatives of 

 this group are cited the Kingfisher, the Woodpeckers, the Tits, 

 Gold-crests (Kinglets), and Nuthatches, the "showy Swallows 

 and Martins," the "gaudy Rollers and brilliant Bee-eaters," the 

 Hoopoe, Wall-Creeper, 'and Common Sheldrake, in which both 

 sexes are equally conspicuous and nest in holes. Reference is 

 also made to the American Orioles (Icteridae) and several Aus- 

 tralian birds- 



The next group consists of ''Birds in which both sexes are dull 

 in colour, and which build covered nests from motives of safety 

 other than concealment." Respecting this group Mr. Dixon 

 says, "I do not think that the fact of dull-coloured females sitting 

 in covered nests can be taken as a serious objection to the law 

 of bright-coloured females sitting in covered nests" : and cites 

 the many other obvious advantages mentioned by Darwin in his 

 •Descent of Man' (Vol. II, p. 168), as protection from enemies 

 or the elements. These advantages are in man}- cases so evident 

 that it seems unnecessary to call in the far-fetched explanation 

 that plain-colored birds nest in this way because they 'may' have 

 descended -from some showy ancestor that built in a covered 

 nest.' A number of instances are then cited showing the advan- 

 tages other than concealment of a covered or domed nest, or 

 of nesting in holes in trees or banks. Other instances of cov- 

 ered nests (presently to be cited) might have been added to show- 

 that such nests are often constructed to serve especiallv as pro- 

 tection from enemies. 



The next group mentioned is that of "Birds in which the 

 female is duller in colour than the male, and which nidificate in 

 covered nests" ; and which is cited as furnishing "convincing 

 proofs of the theory of sexual selection"( !). Yet after mention- 

 ing various species and genera of birds in which 'the female 

 is far less brilliant than the male,' it is suggestively admit- 

 ted, '•nevertheless she sits in a covered nest, although we 

 cannot see any valid reason why she should require concealment 

 during the period of incubation ; in all cases her colours are dull 

 and well adapted for safety in an open nest." Among the 

 •possible explanations' suggested is the very rational one that the 

 domed nests "may be for the purpose of shielding the sitting 

 bird and its charge from cold, or rain, or from some special 



