The red-winged or swamp blackbird[41] in its various forms (fig. 14) is found all over the United States and the region immediately to the north. While common in most of its range, its distribution is more or less local, mainly on account of its partiality for marshes. It builds its nest over or near standing water, in tall grass, rushes, or bushes. Owing to this peculiarity the bird may be absent from large tracts of country which afford no swamps or marshes suitable for nesting. It usually breeds in large colonies, though single families, consisting of a male and several females, may sometimes be found in a small slough, where each female builds her nest and rears her own little brood, while her liege lord displays his brilliant colors and struts in the sunshine. In the upper Mississippi Valley the species finds most favorable conditions, for the countless prairie sloughs and the margins of the numerous shallow lakes afford nesting sites for thousands of red-wings; and here are bred the immense flocks which sometimes do so much damage to the grain fields of the West. After the breeding season the birds congregate preparatory to migration, and remain thus associated throughout the winter.

Three species and several subspecies of red-wings are recognized,[42] but practically no difference exists in the habits of these forms either in nesting or feeding, except such as may result from local conditions. Most of the forms are found on the Pacific side of the continent, and may be considered as included in the following statements as to food and economic status.

Many complaints have been made against the red-wing, and several States have at times placed a bounty upon its head. It is said to cause great damage to grain in the West, especially in the upper Mississippi Valley, but no complaints come from the northeastern section, where the bird is much less abundant than in the West and South.

Examination of 1,083 stomachs showed that vegetable matter forms 74 per cent of the food, while animal matter, mainly insects, forms but 20 per cent. A little more than 10 per cent consists of beetles, mostly harmful species. Weevils, or snout beetles, amount to 4 per cent of the year’s food, but in June reach 25 per cent. As weevils are among the most harmful insects known, their destruction should condone some, at least, of the sins of which the bird is accused. Grasshoppers constitute nearly 5 per cent of the food, while the rest of the animal matter is made up of various insects, a few snails, and crustaceans. The few dragon flies found were probably picked up dead, for they are too active to be taken alive, unless by a bird of the flycatcher family. So far as the insect food as a whole is concerned, the red-wing may be considered entirely beneficial.

The interest in the vegetable food of this bird centers around grain. Only three kinds, corn, wheat, and oats, were found in the stomachs in appreciable quantities. They aggregate but little more than 13 per cent of the whole food, oats forming nearly half of this amount. In view of the many complaints that the red-wing eats grain, this record is surprisingly small. The purple grackle has been found to eat more than three times as much. In the case of the crow, corn forms one-third of the food, so that the red-winged blackbird, whose diet is made up of only a trifle more than one-eighth of grain, is really one of the least destructive species. The most important item of the bird’s food, however, is weed seed, which forms practically all of its food in winter and about 57 per cent of the fare of the whole year. The principal weed seeds eaten are those of ragweed, barnyard grass, and smartweed. That these seeds are preferred is shown by the fact that the birds begin to eat them in August, when grain is still readily obtainable, and continue feeding on them even after insects become plentiful in April. The red-wing eats very little fruit and does practically no harm to garden or orchard. Nearly seven-eighths of its food is made up of weed seed or of insects injurious to agriculture, indicating unmistakably that the bird should be protected, except, perhaps, in a few places where it is overabundant.