SWALLOWS. 141 



3. Partly metallic, male only. Certain Pigeons. 



4. Lustrous or brightly colored ; sexes alike. Crows, cer- 

 tain Jays and Warblers. 



5. Lustrous or brightly colored ; sexes unlike ; females 

 duller, etc. Bluebirds, Martins, certain Warblers, Finches, 

 and Starlings ; also one Flycatcher * (southwestern United 

 States) (and the Blue Crow?). 



6. No metallic tints ; sexes much alike ; male characterized 

 by a color-patch, wanting or much restricted in the female. 

 "Wrens" or Kinglets, Nuthatches, Woodpeckers, certain 

 Warblers (and Finches?). 



7. Male brightly, female plainly colored.^^ Tanagers ; 

 certain Warblers, Finches, and Starlings. 



[8. Plainly colored ; °' with bright crown-patch in both 

 sexes, certain Flycatchers ; with tail brightly tipped, the 

 Waxwings.] 



9. Plainly or dully colored.^" Sexes alike. Thrushes, 

 Gnatcatchers, Titmice, Creepers, Wrens, Wagtails, Vireos, 

 Shrikes, Flycatchers, Swifts, Cuckoos, Owls, most of the 

 Hawks, certain Warblers, Swallows, Finches, Starlings, 

 Jays, and Pigeons. 



10. Plainly or dully colored.''^^ Sexes unlike. *' Goatsuck- 

 ers," Kingfishers, Harriers, and smaller Falcons. Perhaps 

 also certain Finches, the Bobolink, and Blue Crow. 



The Swallows are preeminently insectivorous (perching less 

 often than any other oscine birds), and consequently are mi- 

 gratory. They are also preeminently social and consequently 

 gregarious, at least very often. Most of them breed in com- 

 munities or in colonies, to which they return each spring in 

 greater numbers than before. These settlements, as I have 

 once or twice observed among the Bank Swallows, are formed 

 by a very few pairs, whose number is often but slowly in- 

 creased from year to year. It is probably in this manner that 

 the Cliff Swallows have gradually become dispersed over east- 



* Pyrocephalus rubineiis mexicanus. blue, olive, olive green, and even yel- 



— W. B. low, especially in connection with green, 



^^ Black andiwhite, the various browns are often considered plain colors (chief- 



and grays, are eminently the plain col- ly in contrast), 

 ors. In this sjTiopsis, however, grayish 



