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 Switts, 
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 
