Allen on Sexuai Selection and the Nesting of Birds. I "? "? 



other hand nearly as many birds (probably fully as niany. propor- 

 tionately to their whole number) in which both sexes are among 

 the dullest plumaged of all birds, build a domed nest or nest in 

 holes. Take, for example, the great family of Wrens (Troglodv- 

 tidae), and especially the great South American family Dendro- 

 colaptidae, particularly its subfamilies Furnariinae and Synallaxinae. 

 in which the species as a rule build a domed nest, either of mud or 

 sticks. Some of these nests, as those of the genus Synallaxis and 

 its allies, are among the most remarkable examples of bird archi- 

 tecture, being immense structures (compared with the size of the 

 builders) of sticks, which they enter by narrow, winding passage- 

 ways, or through long tubes of interlocked thorny twigs, the whole 

 .structure being obviously contrived for the purpose of keeping: 

 out enemies. Even birds of the genera allied to Malurus, al- 

 ready mentioned, consisting of species in which both sexes have 

 plain and 'protective' colors, also build domed nests. Even among 

 the Swallows and Martins it is the species having the plainest 

 colors which build in holes in banks, or in the otherwise most 

 concealed and protected situations. Again, the Creepers (genus 

 Certliia) are sexually alike in color, and of eminently plain and 

 protective tints, yet they nest in holes. The Nuthatches and 

 Tits, at least main of them, are no more conspicuous in respect 

 to coloration than perhaps the average of birds which build 

 open nests. In the great famih of American Warblers (Mnio- 

 tiltidse), one of its plainest members, the Ovenbird {Si urns 

 anricapillns) . and one of the few species of the famih in which 

 the sexes are alike, builds a domed nest, contrary to the rule 

 prevailing in the family. In short, scarcely a family or subfam- 

 ily among Passerine birds can be named in which we do not 

 meet with eases of just this character, some of them presenting 

 many such. Consequently it is not the rule that birds which 

 breed in domed nests or in places of concealment are brightly 

 or gayly colored, and that "whenever they [the females] are 

 protected and concealed during the period of incubation they 

 are similarly adorned" (i.e., with "-the same bright hues and 

 strongly contrasted tints of their partners"). 



In view of the real facts in the case, it seems not rash to assume- 

 that concealment of the female during the period of incubation 

 has nothing, or at least very little, to do with this method of nidi- 

 tieation. since it not only does not bear out the theory erected 



