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.
[41] _Agelaius phœniceus_.
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.
[42] Agelaius phœniceus (8 forms), Agelaius gubernator, and Agelaius
tricolor.
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 few complaints come from the northeastern section, where the bird is
much less abundant than in the West and South.
[Illustration: Fig. 14.--Red-winged blackbird. Length, about 9½
Inches.]
Examination of 1,083 stomachs showed that vegetable matter forms 74 per
cent of the food, while animal matter, mainly Insects, forms but 26 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.
Field investigation has shown, however, that, when local conditions
are favorable, large flocks of red-wings may do considerable damage.
Conspicuous among such cases are the losses suffered by farmers to sweet
corn in some of the northeastern States and to milo in the South and
West. In the rather limited grain-raising area of the Imperial Valley
of California the annual damage to milo alone by enormous flocks of
red-wings and yellow-headed blackbirds has been estimated to be fully
$50,000. 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. It is
apparent that where moderately abundant, the red-wing does more good than
harm, but in sections where it becomes excessively abundant a reduction
in its numbers is justifiable.