A 'THEORY OF BIEDS' NESTS. 245 



rich purples, and bright reds, being the most charac- 

 teristic colours. The females are always obscurely 

 tinted, and are often of a greenish hue, not easily 

 visible among the foliage. 



2. Manakins (Pipridce). These elegant birds, whose 

 caps or crests are of the most brilliant colours, are 

 usually of a sombre green in the female sex. 



3. Tanagers (Tanagrid^e). These rival the chatterers 

 in the brilliancy of their colours, and are even more 

 varied. The females are generally of plain and sombre 

 hues, and always less conspicuous than the males. 



In the extensive families of the warblers (SylviadaB), 

 thrushes (Turdidaa), flycatchers (Muscicapidas), and 

 shrikes (Laniadaj), a considerable proportion of the 

 species are beautifully marked with gay and conspi- 

 cuous tints, as is also the case in the Pheasants and 

 Grouse ; but in every case the females are less ga}^ 

 and are most frequently of the very plainest and least 

 conspicuous hues. Now, throughout the whole of these 

 families the nest is open, and I am not aware of a 

 single instance in which any one of these birds builds 

 a domed nest, or places it in a hole of a tree, or under- 

 ground, or in any place where it is effectually con- 

 cealed. * 



In considering the question we are now investigating, 

 it is not necessary to take into account the larger and 

 more powerful birds, because these seldom depend 

 much on concealment to secure their safety. In the 

 raptorial birds bright colours are as a rule absent ; 

 and their structure and habits are such as not to re- 



