BIRDS OF THE UNITED STATES. 
227 
always occurs a few days before their wings are sufficiently developed for 
flight. Even while quite young, in case of accident to the nest, they are 
able to make their way to the top of the chimney. In some cases they 
are carried beyond the reach or notice of their parents. When such occur 
they stubbornly refuse human assistance, although uttering the most pitiful 
cries of hunger. When placed upon the roof contiguous to their native 
chimney. Dr. Brewer has known them to descend to its base, and there 
receive parental attention. In a fortnight they leave the nest, and are 
able to care for themselves. As this species is double-brooded in Penn- 
sylvania the young are necessarily forced to self-maintenance at an early 
age, the thoughts of the parents being engrossed with preparations for a 
second family. These arrangements are perfected about the middle of 
June. In New England, and further north, but one brood is raised. 
Like the old birds, the young are crepuscular rather than nocturnal 
in their habits, preferring to hunt for their prey early in the morning and 
late in the afternoon, or during cloudy weather. At times these predatory 
excursions occur at noonday in the broad glare of a full-orbed sun. The 
period for hunting is apparently regulated by the abundance or scarcity of 
appropriate insects. The adult birds, when with young, have often been 
known to protract their search for food long after night-fall. Caterpillars, 
diptera, beetles and lepidopteia of various kinds, constitute their menu, 
vast numbers of injurious, as well as beneficial sj^ecies, being destroyed. 
Mature insects are chiefly in demand, which the birds, from being con- 
stantly on the wing, procure without much difficulty. Their flight then is 
varied and difficult of description. It consists of rapid sailing, and divers 
turnings, with occasional quickly repeated .strokes of the wings. They 
never rest except in their roosting-places, to the wnlls of which they cling 
with great tenacity, being partially supported by their rigid tails. When 
tired of flight, they seek their homes, which they enter by falling head- 
foremost, wdthout any apparent concern. Their only note in these gastro- 
nomic explorations is a simple cJdp, uttered with considerable force, and 
at times so quickly, as to give rise to a confused twittering. 
