THEIR REPRODUCTION (NESTS) 273 



cunningly so many nests are concealed by har- 

 monising their materials with surrounding tints. 

 In this group, again, we have what appears to 

 be a fatal exception, for there are not a few 

 species in which both sexes are not only dull 

 in colour, but build covered nests or place 

 them in sites well concealed from the outer 

 air. But in these cases we must assume some 

 special advantage in other ways, such as greater 

 warmth and shelter or protection from the sun 

 or certain enemies. Many of the species are 

 exceptionally weak and defenceless, such as the 

 Swifts, Sand-Martins, Wrens, Willow Warblers, 

 and so forth ; whilst the pugnacious Owls seek 

 seclusion because they are mostly nocturnal 

 and dislike the light. What more natural than 

 that they should rear their young in their day 

 retreats ? Lastly, we have a group in which 

 the females are decidedly less showy than the 

 males, and yet rear their young in covered or 

 concealed nests. The Redstarts, some of the 

 Flycatchers, the Chats, and Robin Chats, may 

 be instanced. In some cases, however, the male 

 assists the female in the duties of incubation ; 

 in others some special advantage or protection 

 is doubtless secured. 



We may fittingly conclude the present chapter 



s 



