FOOD AND ITS UTILISATION 91 



the air after flies and gnats, the kiwi running about at night 

 probing for earthworms and looking out for a big phospho- 

 rescent one, a woodpecker making a hole in a tree and 

 another using its sticky tongue to lick ants into its mouth, 

 the oyster-catcher knocking a limpet off the rock with a 

 dexterous stroke of its strong bill, a duck systematically 

 exhausting the mud in a corner of the pond, a heron standing 

 like a statue and suddenly relaxing as the trout flicks past, 

 a solan-goose diving from a height, a creeper running up 

 the tree like a mouse, a kestrel hovering in mid-air and 

 coming down like a bolt — a bolt from the blue for the 

 field- vole. The shrike has not strong feet for holding its 

 booty, it spikes the small mammal or bird, or the large 

 insect, on thorns near its nest ; the nut-hatch, chiefly 

 insectivorous, fixes nuts in crevices and cracks them ; the 

 thrush breaks snail-shells on its anvil ; the skua-gull forces 

 other gulls to disgorge the fish they have caught ; the 

 Greek eagle drops the tortoise from its talons from a great 

 height. 



The snipe's longish bill enables it to probe for small 

 creatures, such as worms, in the mud, and the far back 

 position of the orbits may be adaptive. Dr. F. M. Ogilvie 

 writes : " A snipe, with its eyes placed as they are, can get 

 the very last fraction out of its bill, as it struggles for a 

 worm half an inch further down in the mud, and yet see 

 all that is going on round it, and be ready for any emergency 

 that the fates have in store." The delicate skin prolonged 

 over the bill is rich in nerve-endings with a tactile function. 

 The same is true in the woodcock, which depends very 

 largely on earthworms, and has a very sensitive bill. There 

 is in this case a further adaptation that the tip of the bill is 

 slightly movable by itself and may facilitate the hooking up 

 of the earthworm. 



A peculiarity exhibited by gannets and some other birds 

 is storing food. Gannets frequently fly 50 miles to their 

 fishing-ground, but in spite of the labour thus involved they 

 often collect far more food than they need, a fact un- 

 pleasantly conspicuous in the stench of the colony. Dr. 



