CHAP. XXXIII.] INSTINCT IN BIRDS. 25E 
of the raven and carrion-crow are the best possible implements 
for the half-digging, half-cutting work which they are called 
upon to perform in devouring the dead carcasses of large animals. 
The goosander and merganser, who feed principally on small 
eels and fish, have a row of teeth-like projections inside their 
bill, which, slanting inwards, admits of the easy entrance of their 
slippery prey, but effectually prevents its escape; while the cor- 
morant, whose food consists of larger fish, instead of these 
numerous teeth has a strong curved beak, well fitted for holding 
the strongest sea-trout or haddock. Put your finger into the 
bill of a common duck, and you will see how easily it goes in, 
but how difficult it is to draw it out again, in consequence of the 
sloping projections, by means of which the bird is enabled to 
hold worms and snails. No bill but that of a crossbill could cut 
and divide the strong fir-cones from which it extracts its food. 
The common woodpecker bores holes with its strongly tipped 
wedge-shaped bill in the hard beech-trees, with a precision and 
regularity not to be excelled by the best carpenter; while with 
its long worm-like tongue it darts upon and catches the small 
insects which take refuge in the chinks and crevices of the bark. 
The swallows, who catch their insect prey while flying at speed 
in the air, are provided with large wide-opening mouths, which 
enables them to capture the swiftest flying moth or midge. In 
fact, if we take the trouble to examine the manner of feeding and 
the structure of the commonest birds, which we pass over without 
observation in consequence of their want of rarity, we see that 
the Providence that has made them has also adapted each in the 
most perfect manner for acquiring with facility the food on 
which it is designed to live. The owl, that preys mostly on the 
quick-eared mouse, has its wings edged with a kind of downy 
fringe, which makes its flight silent and inaudible in the still 
evening air. Were its wings formed of the same kind of 
plumage as those of most other birds, it is so slow a flier that 
the mouse, warned by the rustling of its approach, would escape 
long before it could pounce upon it. The heron has also a 
quantity of downy plumage about its wings, which are also of a 
very concave form, and the bird alights in the calm pool without 
making a ripple, and whilst standing motionless, knee-deep in the 
water, it is almost invisible in the gloom of evening, owing to 
