THE FEEDING OF NESTLING BIRDS 201 



We may also take into account the recorded observations 

 of the feeding of young of the Nighthawk (belonging to the 

 Caprimulgidae) which is in the same order as the Hummingbird, 

 viz., the Macrochires. 



Herrick watched the Nighthawk feeding its young, and says 

 (18, p. 134) of the mother approaching the young ones: ' She 

 is loaded with fire-flies, and as her great mouth opens you behold 

 the wide jaws and throat brilliantly illuminated like a spacious 

 apartment all aglow with electricity. With wings erect and 

 full-spread the old bird approached to within fifteen inches of 

 my hand, making an electric display at every utterance of her 

 harsh ke-ark. Then standing over her young, with raised and 

 quivering wings, she put her bill well down into his throat and 

 pumped him full. His down-covered wings were spread and 

 a-quiver. In this position they remained interlocked and silent 

 for one or two minutes." 



Here is a case where, notwithstanding the interlocking of 

 the parent and young for a brief period, the feeding cannot be 

 regarded as regurgitation because the fire-flies were plainly seen 

 in the mouth and throat as the adult approached. The question 

 naturally arises now, may not other cases where the interpretation 

 of regurgitation is based upon interlocking and slight quivering, 

 be very similar to that of the Nighthawk? I am not aware that 

 Herrick interprets this feeding process in terms of regurgitation. 



Incidentally, we may note here the clear evidence of the fact 

 that two families, at least, of the Macrochires feed as do the 

 passerine birds, viz., by the insertion of the adult bill into the 

 mouth or throat of the young. It is well to note this because 

 of the occasional assertion that certain of the Macrochires, e. 

 g., the Micro podia 1 ae, feed the young by taking the nestling's 

 bill into the parental mouth. 



We may now attempt to consider some of the evidence with 

 reference to regurgitation in the Passeres. Perhaps the most 

 extensive paper upon the subject is one by Mrs. Wheelock, 

 published in 1905 (19). While this paper gives the author's 

 observations in greatest detail, her conclusions are best sum- 

 marized in the preface of her book on " The Birds of California," 

 in which it is stated ..." that young of all Macrochires, 

 woodpeckers, perching birds, cuckoos, kingfishers, most birds 

 of prey, and many sea birds are fed by regurgitation from the 

 time of hatching through a period varying in extent from three 



