ANDERSON — THE BIRDS OF IOWA. 283 



In the fall the Swifts congregate in flocks of hundreds at their 

 favorite roosting place, usually some tall deserted chinuiey, for the 

 night, soaring overhead and dashing in one by one. "The flocks 

 drift slowly south, joining with other bands, until on the north- 

 ern coast of the Gulf of Mexico they become an innumerable 

 host. Then they disappear. Did they drop into the water and 

 hibernate in the mud, as was believed of old, their obliteration 

 could not be more complete. In the last week in March a joyous 

 twittering far overhead announces their return to the Gulf coast, 

 but the intervening five months is still the Swift's secret" (W. W. 

 Cooke, "Some New Facts About the Migration of Birds." Year- 

 book Dept. Agri., 1903, p. 386). 



Suborder TROCHIIvI. Hummingbirds. 

 Family TROCHILID^. Hummingbirds. 



The Hummingbirds compose a family of five hundred species, 

 all confined to the new world. Seventeen species are found in the 

 United States, and onlj^ one species reaches Iowa. They feed 

 largely on insects, which they generally capture in flowers, and 

 they also feed on the juices of flowers. Two white eggs consti- 

 tute the nest complement. 



Genus TROCHILUS Liunseus. 



igi. (428). Trochihis colubris{^\\\\\.). Ruby-throated Humming- 

 bird. 

 The Ruby-throated Hummingbird is a common summer resi- 

 dent in all parts of the state from the second week in May to the 

 last of September. John Krider noted the species as very abund- 

 ant in Iowa, "owing to the vast quantities of wild flowers which 

 grow upon the prairies" (Forty Years' Notes, 1879, p. 20). At 

 the present time the species is very commonly found in flower- 

 beds in dooryards, although the nest seems to be generally built 

 in timber — a delicate affair resembling a lichen-covered knot. H. 

 Heaton of Glendale says: "Last June when the black locust trees 

 were in bloom in my dooryard, not fewer than forty humming- 

 birds at a time could be counted flitting among the blossoms' ' 

 (West. Orn., v, 3, 1900, p. 60). 



Order PASSERES. Perching Birds. 



This order includes about six thousand known species, or more 

 than half of all the kinds of birds. The toes are always four, the 



