HIBUNBINIDJE : SWALLOWS. 321 



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

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

 itself, are more or less cosmopolitan, 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 aii<l 

 Gotile are peculiar to tliis 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 (jne 

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

 February and Jlarch 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 liabits of swallows best illustrate the modifying influences of civilization on indigenous 

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

 many do so still. But most of our species have forsaken these primitive liaunts to avaU 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, wliile in the West it retains its 

 old custom of breeding in hoEow 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, Stelgidoxjteryx serripennis. 



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

 Progne suhis, hidoprocne bicolor, Tachycineta thalassina. 



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 ripiaria.) 



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 pei-fectiou in the nesting of Petro- 

 chelidon hmifrons, 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 suhis. 



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



The seven estabhshed North American species, referable to as many modern genera, may 

 readily be determined by the following 



Analysis of Genera and Species. 



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



„„,.,., . , Hirundo erythrorjastra horreorum 159 



2. la. simply emargiuate; lustrous green; beneath white Iridoprocne Uoolcr 160 



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



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



6. Tarsus with tuft of feathers below; lustreless gray; below white Cotile rlpa^la 163 



6. Outer edge of first primary serrate; lustreless brownish ; paler below . . . Stelgidopteryx serripennis 161 



T. Bill very stout, curved ; male entirely lustrous blue-black Progne suhis 165 



49. HIRUN'DO. (Lat. Imundo, a swallow. Figs. 179, 181.) Baen Swallows. Tail deeply 

 forflcate, nearly or about as long as the wings ; lateral feather linear-attenuate, about twice a^ 

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

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

 for this family, of the usual shape, with straight commissure ; nostrils lateral, overarched by x 

 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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