BIRDS OF NEW YORK 179 



after hatching the young are about ready to leave the nest. They are 

 fed from the beginning by regurgitation. The old bird, perching on the 

 rim of the nest and directing her beak vertically downward into the young 

 bird's gullet, proceeds to pump the contents of her crop into the greedy 

 youngster. In the case of nearly every nest which I have watched, I 

 became apprehensive lest some harm had overtaken the young birds 

 because they disappeared so suddenly after 9 or lo days; but I have become 

 convinced that they remain in the nest only 10 days, and then follow the 

 old birds to some secure spot where they are fed for several days longer 

 before they forage for themselves. 



Order PASSERES 



Perching Birds 



" Oil gland nude; skull aegithoghathous ; atlas perforated by the 

 odontoid process; i carotid, left; coeca present, small; muscle formula 

 A X Y; no biceps slip or expansor secondariorum " (Beddard). First 

 toe is directed backward and is on a level with the front toe, that is, per- 

 fectly incumbent; none of the other toes are ever changed in position; 

 the sternum usually has a forked manubrium and a single pair of notches 

 on the rear; the aftershaft is very weak and downy; the flexor hallucis is 

 wholly independent of the flexor communis; the syrinx is well developed 

 with numerous intrinsic muscles to regulate the voice; the formula of the 

 toe joints is 2-3-4-5; primaries are 9 or 10 in number; the tail usually of 

 12 rectrices. In reproductive nature they are all psilopaedic and altricial 

 in nature, the young being bom weak, helpless and nearly naked, and 

 brooded and cared for by the parents for a long time in the nest. 



In this order the high-strung life of bird nature reaches its highest 

 development, the nervous system being acutely sensitive, the special senses 

 keenly developed, at least those of sight and hearing, the circulation and 

 respiration rapid, and the temperature the highest among animals. This 

 is also the largest ordinal group of birds, including nearly all our familiar 

 land birds and over one-half of the entire number of birds. The order is 

 subdivided according to the development of the syrinx and its intrinsic 

 muscles, as well as the condition of the tarsus. 



