8 BIRDS' NESTS 



Second, Haunt. — - The nature of a bird's haunts is often 

 reflected in its nest through the materials employed in construc- 

 tion. Coots and Yellow-headed Blackbirds (Group, Hall No. 

 308), Red-winged Blackbirds and Marsh Wrens (Group, Hall 

 No. 304) use reeds and marsh grasses; field-inhabiting birds 

 employ the grasses and weed-stalks they find about them, and 

 leaves enter largely into the nest of wood-loving birds. (Exam- 

 ine the groups of the Field Sparrow and the Oven-bird in Hall 

 No. 308.) 



Third, Structure of the Bird. — Although birds possessed of the 

 same type of nest-building tools, that is, bill and feet, may build 

 wholly unlike nests (compare the Cliff and Bank Swallows and 

 their nests. Groups in Hall No. 208) the character of the nest is in 

 some degree affected by the structure of the bird. Thus a soft- 

 billed Dove would not be expected to hew out a cavity in trees 

 as do the Woodpeckers, nor could the weak-footed, short -billed 

 Whip-poor-will cling to swaying branches and weave the Oriole's 

 pendent cradle. 



Fourth, Necessity for Concealment. — While concealment is 

 secured chiefly through the selection of a site, it is also obtained 

 in the building of the nest. The Oriole's deep cradle (Group, Hall 

 No. 308) is a good type, and further illustrations are furnished 

 by the admirably designed nests of the Oven-bird and Humming- 

 bird, each of which, in a wholly different way, is made to resem- 

 ble its immediate surroundings. 



Variations in Nesting Habits. — The existing nesting habits of 

 birds have doubtless been developed through adaptations to 

 changing conditions, and it is of especial interest, therefore, to 

 note any variation in the character of a bird's nest or nesting site 

 and to learn whether the change is a response to some new factor 

 in environment. Barn and Eaves Swallows, Chimney Swifts, 

 Phoebes, Bluebirds and Wrens, for example, have, as a result of 

 the invasion of their haunts by man, adopted new types of nesting 

 sites, while Orioles, Vireos, House Finches and other species often 

 find strings, rags and paper more desirable nest-material than 

 fibres, rootlets and bark. 



Second Broods. — Several of our earlier nesting species, the 

 Robin, Song Sparrow and Phoebe, for example, rear second and 



