MIMICRY. 467 



thesis that supposing certain caterpillars not very particular as 

 to their food, either Elm, Lime, Birch, &c, and further assuming 

 that such caterpillars were more easily overlooked on Birch by 

 resembling the catkins of that tree, then those broods which fed 

 on trees other than Birch would be most likely to be devoured 

 by enemies, and so gradually a race would grow up which 

 invariably fed on Birch.* 



The active mimicry here discussed does not deal with the 

 mimicking by birds of the songs of their fellows. This imitative 

 faculty had been recorded of birds in captivity by Aristotle. But 

 in a state of nature the same thing occurs. Mr. Butterfield has 

 narrated his having heard a Whinchat, a bird of no extensive 

 vocal capacity, imitate "in quick succession the song of the Wren, 

 Song Thrush, Chaffinch, Corn Bunting, Tree Pipit, Greenfinch, 

 and Starling." f Mr. Biley Fortune has known the Starling to 

 give perfect imitation of the cries of the Sparrow, Lapwing, 

 Golden Plover, Chaffinch, Blackbird, Yellowhammer, Thrush, 

 Jackdaw, Swallow, and many other birds. I Prof. Lloyd Morgan 

 is of opinion that " mimetic activities are due to a mimetic im- 

 pulse. Some of them are probably involuntary and due to connate 

 impulse; but others are certainly due to intelligent imitation. "§ 

 Thus Lumholtz, in Queensland, observed the mental process in 

 the Lotus-bird (Parra gallinacea) : " The grown bird is not shy, 

 but the young are extremely timid. I had once or twice seen the 

 old birds with young, but as soon as I approached them the 

 young always disappeared, while the old birds walked about 

 fearlessly, as if there was no danger. It long remained a mystery 

 to me how they could conceal themselves so well and so long, but 

 one day the problem was solved. An old bird came walking with 

 two young ones near shore. I hid behind a tree and let them 

 come close to me. As I suddenly made my appearance, the 

 small ones dived under the water and held themselves fast to the 

 bottom, while I watched them for a quarter of an hour before 



* Extr. MS. Lecture to the Bakewell U. E. Students' Association. 



f ' Zoologist,' 1877, p. 384. — Mr. Godfrey in these pages (ante, p. 267) 

 has also corroborated this bird's power of mimicry. 



I 'Ornithology in relation to Agriculture and Horticulture' (1893), 

 p. 142. 



§ ' Natural Science,' vol. vi. p. 328. 



2h2 



