68 BEHAVIOR OP PIGEONS. 



crop is shaken, and with it the whole body, especially the wings. The power to regurgitate 

 is, then, common to doves, old and young, and it has come secondarily into service in the 

 care of the young. 



What prompted J to feed its white companion? I think the crop was a little over- 

 loaded, and that, together with the stimulus of a teasing beak, led it to give up food. 

 It was not, however, an act of vomiting merely; for J offered its open beak several times 

 to the companion, and in a way that was unmistakable, so that I wondered at it before 

 the feeding began. When the beak was inserted in the open beak the whole machinery of 

 correlated movements was set in motion and the young bird behaved in all respects 

 like an adult bird. The beak inserted in the throat may have much to do with stimulating 

 the process. 



A hybrid between a ring-dove and the European turtle was 11 days old; it had as a 

 nest companion a ring-dove 1 week old. The ring was small and covered with pin-feathers; 

 the hybrid had many wing-coverts and scapulars unfolding. These birds were under the 

 care of a pair of ring-doves; both were perfectly healthful and strong. I noticed the young 

 ring teasing the hybrid with its beak, as young birds scantily fed often do with a nest- 

 mate. The vigorous billing about the hybrid's beak and neck led it to feel like feeding, 

 and it opened its beak several times for the ring, and once after offering the open beak, 

 it put its head down and shook its wings and crop as an old bird does in feeding. The 

 young ring did not get its beak into that of hybrid, but came near doing so. (R 24.) 



TRANSFERENCE OF YOUNG TO FOSTER PARENTS. 



The young of any species may be transferred to foster-parents, provided they are 

 put under the foster-parents at the time the eggs of the latter are due to hatch. It does not 

 seem to make any difference whether the young birds are transferred when they are just 

 hatched, or at a week or 2 weeks old, provided only that they are not old enough to stand 

 up straight and raise the head too high. The old birds do object to taking care of any 

 young birds that stand up and look too much like old birds. If the young simply sits 

 down, holds its head down in the proper position for care, that is all that is required; 

 the old birds will feed it just as well as if it were hatched out under them. If eggs are 

 transferred one must always be sure that they are properly timed; that is, timed to hatch 

 with the eggs which are removed; if they hatch too early, or are due to hatch too long 

 after the tune of the eggs removed, the transfer is not successful. The foster-parents 

 are as well satisfied with the eggs of other species as with their own; they do not know the 

 difference. 



The necessity of exactly matching the time of hatching of the transferred eggs with 

 that of the eggs removed is one of the complications that is met with in attempts, such as 

 my own, to obtain and hatch unusually large numbers of eggs from particular pairs of 

 birds. I have had some trouble of this sort. The common pigeons, however, are a little 

 less particular in the matter of the exact time the eggs are due to hatch than are the wild 

 species. Also, in crossing common pigeons with the wild species one finds that the former 

 will usually continue the incubation a few days after their mate's usual time. The wild 

 passenger-pigeon never waits more than 10 or 12 hours. If the egg does not hatch within 

 that time he leaves it; even if the shell is broken and the bird is nearly ready to hatch 

 it is deserted. If young are put into their nests before they are due to hatch they are not 

 able to feed them; much care in this matter is necessary. "Pigeon milk," as it is called, 

 seems to be ready at the proper moment. Everything is well-timed, and if there are 

 young birds in the nest before this time arrives they will get no food. (SS 10.) 



Fulton, in pages 42-43 of the work previously cited, contributes the following 

 on the subject under discussion: 



