This section is from the "The New Student's Reference Work Volume 5: How And Why Stories" by Elinor Atkinson.
One sunny Saturday afternoon in June, a tanned, dusty-legged boy came to the doctor's side porch. In one hand he had a soft, limp bundle of snow-white, dead-black and rose-colored feathers. In the other he carried a sling-shot! A shame-faced lad he was, for not a boy in the town would purposely kill one of the doctor's birds. He had just aimed at the tempting singer on the picket fence of the vegetable garden.
"But doctor," he said, "perhaps you don't know that this bird was eating your green peas. I saw him."
"Let us see," said the doctor. He opened the little crop, under the rosy spot on the breast that would throb with song no more. Yes, there were as many as two pods full of young peas. But the little vestibule to the stomach was packed full of potato bugs—the striped Colorado beetles that were eating all the potato patches in the town.
Out on the picket fence the mother grosbeak had all her babies in a row, and was feeding them the beetles. Black-headed grosbeaks were there, too. In a few days the doctor's potato plants were picked clean, and the birds were foraging in nearby gardens. "One pair of grosbeaks brings up a brood of four or five in a season," said the doctor. " One pair of Colorado beetles breeds to 50,000,000. For the good potatoes these pretty singers help me grow, I can spare them a whole row of peas."
That was a lesson one little girl never forgot. The doctor always opened the crops and stomachs of dead birds. In a robin's stomach in June he found a few orchard cherries, among the insects and wild fruits..
"The robin comes to us in March," he explained to a sober little group. " For three months he has nothing but worms, ground beetles and dry, winter berries to eat. He brings up one brood of babies on such food. No wonder he wants a few juicy cherries in June. But he likes the Russian mulberry just as well, and we don't care for that fruit." The doctor made a note to plant a mulberry tree for the robins, cedar-birds and other orchard lovers. Nine-tenths of the robin's food is insects and wild fruits. Only in June and July does he eat cherries to pay for the six months' work he does for us so cheerfully. He eats beetles, grubs, worms, caterpillars, spiders, snails, grasshoppers, wild grapes, blue-berries, service berries, choke berries, black alder and holly-berries, rose hips and the seeds of sumac.
There were always dead birds for the doctor to study. Woeful little tragedies happened in the nests. Once, a pretty mother oriole was hanged by a loop of horse hair, in a nest she was weaving. For hours the mate made wild lament for his loss. Then, a high wind tumbled the half-finished nest and the dead weaver to the ground. Nothing but insects were in the little stomach—beetles, ants, wasps, spiders, bark scales, plant lice and caterpillars. In mid-summer the oriole eats a few grapes and peas. Can't we spare her those for the countless insects she eats and feeds to her babies?