PICK-AXES AND PROBES 45 



East also have the bow-bill, and no doubt this is 

 often used as a probe ; but on keeping some speci- 

 mens of the Rusty-cheeked Babbler (Pomatorhinus 

 erythrogenys) in India in a small aviary with a 

 deep bed of sand on the floor which had become 

 hardened, I was astonished to find them vigorously 

 using their long curved beaks as pick- axes, digging 

 up the ground as if a corps of pigmy navvies had 

 worked at it. The beak is evidently adapted for 

 much wear and tear, as I found on buying these 

 birds that in some it was much overgrown from 

 want of use, and had to be cut back. 



But the most remarkable beak found among 

 insectivorous birds is that of the Huia of New 

 Zealand (Heteralocha acutirostris) ; not so much 

 from the peculiarity of the bill itself, as because 

 of its different shape and use in the two sexes, a 

 phenomenon unknown elsewhere among vertebrate 

 animals, since, however different the sexes may be 

 in general appearance, their means of obtaining food 

 are practically identical. But in the Huia, although 

 the plumage and size are identical in both sexes, the 

 beaks are as different as those of a Woodpecker and 

 a Tree-creeper, the male having a strong, straight 

 digging bill of moderate length, and the hen a 

 long, curved, slender, probing one, twice as long 

 as her husband's pick- axe. 



The late Sir Walter Buller, in his admirable 

 book on the birds of New Zealand, tells us how he 

 was able to study the actual use of their very diverse 

 bills by these birds. He had a pair brought to 



