40 
ALLEN’S naturalist’s LIBRARY. 
Studer say that many perish, as, of course, the supply of insects, 
on which these birds entirely depend, fails them. The nest is 
a rough structure, formed of many materials, all of which are 
procured by the Swifts on the wing, as the short feet and long 
wings of the bird prevent its rising when once it gets on the 
ground, and so it is often captured when benumbed with cold. 
Thus the nest is composed of earth procured from the crevices 
of rocks, leaves, paper, feathers, &c., all the materials being 
glued together into a compact mass by means of the birds’ own 
saliva. The eggs are laid before the nest is completed, and 
much of the structure is consolidated by the sitting birds, both 
male and female sharing the duties of incubation. In their 
habits the White-bellied Swifts are very regular, issuing forth 
from their retreats at break of day and foraging for food for 
some hours, then resting in their homes during the best part 
of the day, and sallying forth again about five o’clock in the 
afternoon, and flying about till dark. They are very quarrel- 
some and irritable in their nature, and make a considerable 
noise and clatter in the places where they take up their 
abode. 
Eggs.— Generally two in number, but sometimes three or 
even four, though it is supposed that no female lays more than 
two eggs. Eggs pure white. Axis, I'l-i'as; diameter, 075- 
0 - 8 . 
II. THE COMMON SWIFT. MICROPUS APUS. 
Hirundo apus, Linn. Syst. Nat. i. p. 344 (1766). 
Micropus murarius, Meyer und Wolf, Taschenb. p. 281 (1783); 
Macgill. Brit. B. iii. p. 618 (1840). 
Cypselus apus. Dresser, B. Eur. iv. p. 583, pi. 266 (1881) ; 
Newt. ed. Yarr. Brit. B. ii. p. 364 (1882)3 O- U. List 
Brit. B. p. 74(1883); Seeb. Brit. B. ii. p. 292 (1884); 
Lilford, Col. Fig. Brit. B. part v. (1887); Saunders, Man. 
Brit. B. p. 251 (1S89). 
Adult Male. — Sooty-black with a slight greenish gloss, the 
forehead slightly whiter ; chin dull white, with a few shaft-lines 
on some of the feathers ; under wing-coverts with faintly in- 
dicated whitish margins, these being sometimes visible on the 
under tail-coverts ; bill black ; feet dark brown ; iris dark 
