HIBUNDINIDM': SWALLOWS. 321 



A hundred species of swallows are recorded ; probably about tliree-fourths of them are 

 goiuiiuo. They are distributed all over the world; the most generalized types, like Hirundo 

 itself, are more or less cosmupolitan, but each of the great divisions of the globe has its peculiar 

 subgenera or particular sets of species. Thus, all the American groups except Hirundo and 

 Cotile are peculiar to this continent. 



Swallows are insectivorous, and therefore migratory in cold and temperate latitudes ; 

 unsurpassed in powers of flight, they are enabled to pass with ease and swiftness from one 

 country to another, as the state of the weather may require. With us a few warm days in 

 February and March often allure them northward, only to be driven back again by the cold, 

 giving rise to the well-known adage. No birds are better known to all classes than these, and 

 none so welcome to man's abode, — cherished witnesses of peace and plenty in the homestead, 

 dashing ornaments of the busy thoroughfare. 



The habits of swallows best illustrate the modifying influences of civilization on indigenous 

 birds. Formerly, they all bred on cliffs, in banks, in hollows of trees, and similar places, and 

 many do so still. But most of our species have forsaken these primitive haunts to avail them- 

 selves of the convenient artificial nesting-places that man, intentionally or otherwise, provides. 

 Some are just now in a transition state ; thus the purple martin, in settled parts of the country, 

 chooses the boxes everywhere provided for its accommodation, while in the West it retains its 

 old custom of breeding in hollow trees. The nesting of our swallows now presents the follow- 

 ing categories of method : — 



1. Holes in the ground, dug by the bird itself, slightly furnished with soft material : Cotile 

 riparia, Stelgidopteryx serripennis. 



2. Holes in trees or rocks not made by the birds, fairly furnished with soft material : 

 Progne siibis, L-idoprocne bicolor, Tachycineta ihalassina. 



3. Holes, or their equivalents, not made by the birds, but secured through human agency, 

 and more or less fully furnished with soft material, according to the shallowness or depth of the 

 retreat. (Formerly, no species; now, all the species excepting Cotile riparia.) 



4. Holes constructed by the birds, of mud, plastered to surfaces, whether artificial or natural, 

 and loosely furnished with soft material. This is seen in perfection in the nesting of Petro- 

 chelidon lunifrons, and is imperfectly illustrated by the nidification of Hirundo horreorum. 



5. Eggs pure white, unmarked: Iridoprocne bicolor, Tachycineta thalassina, Cotile ripa- 

 ria, Stelgidopteryx serripennis, Progne subis. 



6. Eggs thickly speckled : Hirundo horreorum, Petrochelidon lunifrons. 



The seven established North American species, referable to as many modem genera, may 

 readily be determined by the following 



Analysis of Genera and Species. 



1. Tail deeply forficate, with linear lateral feathers ; lustrous steel-blue above, rufous below 



Hirundo erythrogastra horreorum 159 



2. Tail simply emarginate; lustrous green; beneath white Iridoprocne hicol<yr 160 



3. Tail simply emarginate; opaque velvety-green; beneath white Tachycineta thalassina 161 



4. Tail nearly even; lustrous steel-blue; rump rufous Petrochelidon lunifrons 162 



5. Tarsus with tuft of feathers below ; lustreless gray ; below white Cotile riparia 163 



6. Outer edge of first primary serrate ; lustreless brownish ; paler below . . . Stelgidopteryx serripennis 164 



7. Bill very stout, curved ; male entirely lustrous blue-black Progne subis 165 



HIRUN'DO. (Lat. /wVMwtio, a swallow. Figs. 179, 181.) Barn Swallows. Tail deeply 

 forficate, nearly or about aslong as the wings ; lateral feather linear-attenuate, about twice as 

 long as the middle feather. Tarsi shorter than middle toe and claw, above feathered for a little 

 distance ; basal joint of middle toe partly adherent to both lateral toes. Bill of moderate size 

 for tliis family, of the usual shape, with straight commissure ; nostrils lateral, overarched by a 

 membranous scale. Upper parts glossy, dark-colored ; a dark pectoral collar ; forehead and 

 under parts rufous ; tail spotted with white. Eggs colored. Sexes similar. 



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