74 MATERIAL 



woodland birds generally employ twigs, rootlets, bark, leaves, mosses, 

 etc., while field-inhabiting species, as a rule, use chiefly dried grasses. 

 It follows, therefore, that a change in the nature of a bird's haunts 

 often causes more or less variation in the character of its nesting mate- 

 rial. In the North, for example, the Acadian Flycatcher builds its nest 

 of plant-stems, grasses, and dried blossoms, but in Florida it uses the 

 Spanish or Tillandsia 'moss,' a material, by the way, which enters into 

 the nests of many birds. In the East, Night Herons, building in trees, 

 use sticks; in the West, where they nest in marshes, the nest is composed 

 of reeds. There are many similar instances. 



A familiar case of local variation, due to change in environment, 

 is furnished by the Baltimore Oriole, which gathers string, worsteds, 

 etc., in place of plant fibers; and experimenters have tried to determine 

 the bird's choice of colors by supplying it with worsteds of varied hues, 

 without, however, other result than a demonstration of range in choice 

 among different individuals, since some selected gay and others dull 

 colors. 



The use by birds of rags, paper, horse-hair, etc., also clearly illus- 

 trates the influence of civilization on the bird's selection of material 

 with which to build a nest. 



The necessity for concealment is, in some cases, a potent influence 

 in the choice of nesting material. What is generally spoken of as 'nest 

 decoration,' if it have any significance, is assuredly not designed to 

 make the nest conspicuous through display, but inconspicuous by 

 matching it with its surroundings. The lichen-covered nests of the 

 Wood Pewee, Blue-gray Gnatcatcher, arid Hummingbird are examples 

 of this class. 



The Great-crested Flycatcher introduces a bit of cast-off snake- 

 skin into its nest, it has been said, to serve the purpose of a scare-crow. 

 The explanation is important if true but lacks evidence to support it. 



The student should try to observe the methods employed by birds 

 in gathering and carrying the material for their nests, noting, for 

 example, Robins, Barn and Eave Swallows picking up billfuls of mud, 

 a Chimney Swift breaking off dead twigs with bill or feet, a Humming- 

 bird collecting lichens from a tree-trunk, an Oriole tugging at a plant 

 fiber, etc. 



Construction. Then follows a study of nest-construction, from the 

 simple method of the Skimmer which by squatting low and turning 

 around again and again hollows a nest in the sand, to the more complex 

 activities of Swallows, Swifts and Orioles, which respectively exhibit 

 the arts of the mason, joiner and weaver. Herrick's detailed and, so far 

 as I am aware, unique study of a pair of Robins while nest-building, 

 should be read in this connection. The work may be performed by one 

 or both sexes. In the former case the female is usually the builder when 

 the male may assist by bringing material. The nest may be completed 

 in a day and occupied at once, or a longer time may be required and it 

 may apparently be deserted for days after its completion. The weather, 



