Fig. 11.—Purple grackle. Length, about 12 inches.
Large flocks of grackles no doubt do considerable injury to grain crops, and there seems to be no remedy, except the destruction of the birds, which is in itself expensive. During the breeding season, however, the species does much good by eating insects and by feeding them to its young, which are reared almost entirely upon this food. The bird does the greatest amount of good in spring, when it follows the plow in search of large grubworms, of which it is so fond that it sometimes literally crams its stomach full of them.
[BREWER BLACKBIRD.]
The Brewer blackbird[36] takes the place in the Western States of the grackle, or crow blackbird, which lives in the Mississippi Valley and farther east and is very similar in appearance and habits. It breeds east to the Great Plains and north into Canada, and winters over most of its breeding range in the United States and south to Guatemala. At home in fields, meadows, and orchards, and about ranch buildings and cultivated lands generally, it nests in bushes and weeds, sometimes in trees, and is very gregarious, especially about barnyards and corrals. The bird feeds freely in stockyards and in cultivated fields, and when fruit is ripe does not hesitate to take a share. During the cherry season in California the birds are much in the orchards. In one case they were observed feeding on cherries, but when a neighboring fruit grower began to plow his orchard almost every blackbird in the vicinity was upon the newly opened ground close after the plowman’s heels in its eagerness to secure the insects turned up.
[36] Euphagus cyanocephalus.
The laboratory investigation of this bird’s food covered 312 stomachs, collected in every month and representing especially the fruit and grain sections of southern California. The animal portion of the food was 32 per cent and the vegetable 68 per cent.
Caterpillars and their pupæ amounted to 12 per cent of the whole food and were eaten every month. They include many of those pests known as cutworms. The cotton-boll worm, or corn-ear worm, was identified in at least 10 stomachs, and in 11 were found pupæ of the codling moth. The animal food also included other insects, and spiders, sow bugs, snails, and eggshells.
The vegetable food may be divided into fruit, grain, and weed seeds. Fruit was eaten in May, June, and July, not a trace appearing in any other month, and was composed of cherries, or what was thought to be such, strawberries, blackberries or raspberries, and fruit pulp or skins not further identified. However, the amount, a little more than 4 per cent for the year, was too small to make a bad showing, and if the bird does no greater harm than is involved in its fruit eating it is well worth protecting. Grain amounts to 54 per cent of the yearly food and forms a considerable percentage in each month; oats are the favorite and were the sole contents of 14 stomachs, and wheat of 2, but no stomach was completely filled with any other grain. Weed seeds, eaten in every month to the extent of 9 per cent of the food, were found in rather small quantities and irregularly, and appear to have been merely a makeshift.