28 THE RIDDLE OF MIGRATION 



striking contrast to that of mammals, the nostrils 

 are not fleshy and sensitive but openings in a horny 

 bill, pushed backward to the base, a place of second- 

 ary importance. The cavity behind the nostrils 

 boasts but few turbinal bones, entirely insignificant 

 in comparison with mammals, the whole arrange- 

 ment suggesting that the nasal organ in birds is now 

 largely decadent. Some birds (e.g. pelican, gannet) 

 actually have the nares entirely closed in the adult. 

 In the New Zealand kiwi alone, a flightless bird of 

 nocturnal habits, are the nostrils found at the tip of 

 the bill. Carefully devised experiments have dem- 

 onstrated a sense of smell — and a poor one at that — 

 in only a few species of birds. Even the vulture, so 

 widely accredited with a particularly acute olfactory 

 sense, is incapable of discovering meat in an ad- 

 vanced state of decomposition if it is wrapped in 

 paper, even though the bill may actually come in 

 contact with the parcel. On the right side of the 

 wind, on the other hand, a carnivorous mammal 

 would speedily find the packet at a great distance. 

 Taste is without doubt a poorly developed sense 

 in birds. The fact that certain birds will refuse 

 their normal food if it has been coated with unpleas- 

 ant chemicals demonstrates a power of discrimina- 

 tion, while the undoubted selection exhibited among 

 many insectivorous birds no doubt reflects the same 



