RECOGNITION OF RELATIVES 247 



commented on resemble each other in voice, even 

 when this differs greatly in the two sexes, as in the 

 Ducks of the genus Anas mentioned, and birds at 

 once recognize and respond to a sufficiently accurate 

 reproduction of their call, as all field-naturalists 

 are well aware. Thus, I have made both a wild 

 jungle-cock and tame roosters answer me, though 

 I am unable to imitate more delicate notes, and 

 have made wild Duck circle round and lower their 

 flight by quacking to them. People who do not 

 want vicious cocks, by the way, should carefully 

 refrain from mocking their birds thus, as when the 

 fowl's brain has grasped the location of the chal- 

 lenge in the human, he will attack, and remain 

 permanently spiteful, in which case he is dangerous 

 to small children. 



Different species too far apart to readily inter- 

 breed will associate if the note is similar, as in the 

 case of the Whistling Tree-Ducks (Dendrocycna), 

 when specimens find themselves isolated in cap- 

 tivity, different though they may be in colour. 

 But allied species have a wonderful knack of know- 

 ing each other by sight, even if colour and voice 

 are both different ; thus, the Mandarin and Caro- 

 lina drakes not only occasionally make love to each 

 other's females, which is not surprising, as these 

 are so much alike that one generally has to look at 

 them twice to see which is which, but the females 

 will reciprocate, although the two male birds are 

 very distinct both in coloration, decorative plumage, 

 and voice. 



