“These conditions are fulfilled in the highest degree in the swallow and the martin, both of which hunt flying insects, pursuing them this way and that, back and forth, ceaselessly and with a thousand subtle tricks. They catch them in their wide-open and viscous gullet, and continue their course without a moment’s pause.
“The bird that lives on grain and seeds, the granivorous bird, as it is called, has a beak that is very wide at the base and adapted by its strength to the opening of the hardest seeds. In this class are the chaffinch, the greenfinch, the linnet, the goldfinch, and the swallow. The bird that lives on insects, or [[303]]the insectivorous bird, has a beak that is fine and slender, in delicacy proportioned to the softness of its prey. To this number belong the nightingale, the warbler, the fallow-finch, and the wagtail. Agriculture has no better defenders against the ravages of worms than these little birds with slender beaks, voracious devourers as they are of larvæ and insects.
“But the granivorous birds have certain grave faults: some of them are addicted to pilfering in the grain-fields and know how to get the wheat out of the ear, and some even come boldly to the poultry-yard to share with its inmates the oats thrown to them by the farmer’s wife. Others prefer the juicy flesh of fruit, and know sooner than we when the cherries are ripe and the pears mellow. Such failings, however, are amply atoned for by services rendered. The granivores pick up in the fields an infinite number of seeds of all sorts which, if left to germinate, would infest our crops with weeds.
“To this rôle of weeder they add a second not less meritorious. Grain and seeds are, it is true, their regular diet; but insects are to few of them so despicable as to be refused when sufficiently plentiful and easy to catch. Indeed, we can go still further in our commendation of these birds: in their early days when, feeble and featherless, they receive their nourishment by the beakful from their parents, many of them are fed on insects.
“Let us take for example the house-sparrow. Here we have, it must be admitted, an inveterate [[304]]devourer of grain. He robs our dove-cotes and poultry-yards, steals their food from the pigeons and the hens, and anticipates the farmer in reaping the grain-crops near his house. Many other misdeeds are to be reckoned against him. He plunders the cherry-trees, commits petty larceny in the garden, plucks up sprouting seeds, and regales himself on young lettuce and the first leaves of green peas. But as soon as the season of insect-eggs opens, this shameless pilferer becomes one of our most valuable helpers. Twenty times an hour, at least, the mother and the father take turns in bringing the beakful of food to their little ones; and each time the bill of fare consists of a caterpillar, or an insect large enough to be divided into quarters, or perhaps a fat larva, or it may be a grasshopper, or some other kind of small game.
“In one week the young brood consumes about three thousand insects, larvæ, caterpillars and worms of all species. There have been counted in the immediate vicinity of a single nest of sparrows the remains of seven hundred June-bugs, besides those of innumerable smaller insects. That is the supply of food required for rearing only one brood. Let us then, my children, wish well to all the little birds that deliver us from that formidable ravager, the insect.” [[305]]
CHAPTER LVI
BIRDS’ NESTS
“It is in the building of nests destined for the rearing of a family of young ones that the bird shows in a remarkable way that wonderful faculty which enables the little creature to accomplish, without previous training, results that would seem to require the intervention of reasoned experience.