other substances are also eaten, but they are mostly of the same general character, such as hard seeds of grasses or weeds, with but little indication of fruit pulp or other soft vegetable matter. The following table shows the various grains and seeds identified, with the number of stomachs in which they were contained:

Grain:
Corn

Vegetable substances found in stomachs of cowbirds.

Stomachs. Weeds-Continued.

Pennyroyal (Trichostema dichotomum)

Stomachs.

56

Wheat

20

2

Oats are apparently the favorite grain with the cowbird, as they were found in 102 stomachs, a record which exceeds the total of those containing either wheat or corn. They first appear in March, when 12.9 per cent are eaten, evidently waste grain picked up in the stubblefields, highways, and barnyards, except in the southern part of the country, where sowing may take place as early as this month. Oats constitute less than 2 per cent in April, nearly 8 percent in May (probably partly made up of grain from newly sown fields), 3.7 in June, 25.1 in July, 31.5 in August, 19.4 in September, and after that decrease rapidly and reach zero before the 1st of November. The average consumption for all the months of the year is 8.6 percent. Corn was found in 56 stomachs, but the irregular manner in which it. is distributed through the food of the year indicates that it is not a favored diet. The record for January, which shows a little more than 33 per cent, is based on only 3 stomachs, and so can not be considered very reliable. In any case the corn eaten must have been scattered grain, unless it was some that had been left in the shock over winter. Even in October, when corn is abundant everywhere, it is scarcely touched. Only 1 bird out of 70 taken in that month had eaten any, and in this single instance it amounted to only 6 percent of the entire food. In the other months the quantity ranges downward to zero, but in such an erratic manner as to indicate that it is never sought, but merely eaten when found and when better food is not at hand. The

aggregate for the year is 6.5 percent. Wheat was found in only 20 stomachs, and amounts to 1.4 percent of the year's food. Like corn, its distribution is irregular and does not appear to have any relation to the seasons. It is probable that it is a purely accidental food, eaten only when nothing better is to be had. The greatest quantity (4.8 percent) was taken in September. A single kernel of buckwheat was found in 1 stomach.

Grain as a whole amounts to 16.5 percent, or practically one-sixth of the food of the year; but a consideration of its distribution as given above leads to the conclusion that a large portion of this, probably one-half, is waste. In comparing the record of the cowbird with that of the red-winged blackbird, the cowbird's shows the greater consumption of grain; that is, 16.5, as against 13.9 for the redwing. In view of this fact it would seem somewhat strange, were not a large proportion of the grain consumed waste, that no complaints should have been made against the cowbird on the score of grain eating. It is possible, of course, that observers have not always distinguished the two species in the field, as male cowbirds do not differ greatly in color or size from female redwings-and their great abundance in the West lends some color to this supposition. But it seems far more probable that they gather a very important part of the grain found in their stomachs in their gleaning in roads, about barnyards, and wherever cattle are found, and so do far less actual damage to growing crops than the redwings.

Fruit forms an insignificant part of the food. Some traces of what may have been fruit pulp were found, and a few seeds of raspberries were in each of 4 stomachs, and some blueberry seeds in one; but as some of the raspberry seeds were in stomachs collected in April they were evidently eaten as dry seeds, and this may have been true of all. The seeds of plants classified as weeds in the list of vegetable food constitute by far the most important part of the diet. They form the largest item of food in every month except July and August, and are of importance in every month. Beginning with 64.4 percent in January and 95.5 percent in February, they slowly decrease to 16.6 percent in August, but rise suddenly to 58.1 percent in September, attain their maximum of 97 percent in October, and end with 96.8 percent in December. They constitute practically the whole food of the winter months. The aggregate for the year is 60 percent of all the food, or more than three-fourths of the vegetable food, and more than three and a half times the total amount of grain. Barngrass and ragweed are especially well known as troublesome weeds throughout the country wherever field crops are cultivated, and these two constitute the great bulk of this food. Barngrass seed was found in 265 stomachs and ragweed in 176. Panicums, while ostensibly forage plants, are often troublesome weeds. Their seeds were found in 133

1 Based on 3 stomachs. A larger number would probably greatly increase the percentage.

stomachs, which shows that the birds relish them. Knotweed, smartweed, and other species of the genus Polygonum, all noted weeds, were found in 49 stomachs. The other items of the weed-seed food are eaten to a greater or less extent, but not by so many birds as are those specifically mentioned. Of the 544 stomachs only 2 were filled with grain alone, while 94 contained nothing but weed seed. The amount of weed seed destroyed by birds in a single year in the United States is immense, and it is evident that the cowbird is one of the noteworthy agents by which the already overflowing tide of noxious weeds is kept within its present limits.

SUMMARY.

In summing up the results of the investigation, the following points may be considered as fairly established: (1) Twenty per cent of the cowbirds' food consists of insects, which are either harmful or annoying. (2) Sixteen per cent is grain, the consumption of which may be considered a loss, though it is practically certain that half of this is waste. (3) More than 50 per cent consists of the seeds of noxious weeds, whose destruction is a positive benefit to the farmer.

is practically not eaten.

(4) Fruit

The following table shows the percentage of each of the principal kinds of food for every month in the year:

Food of the cowbird.

[NUMBER OF STOMACHS EXAMINED: January, 3; February, 10; March, 18; April, 83; May, 99; June, 53; July, 57; August, 38; September, 79; October, 70; November, 23; December, 11. Total, 544.]

In view of the fact that so much has been said in condemnation of the cowbird's parasitic habits, it may not be out of place to inquire whether this parasitism is necessarily as injurious as has been claimed. When a single young cowbird replaces a brood of four other birds, each of which has food habits as good as its own, there is, of course, a distinct loss; but, as already shown, the cowbird must be rated high in the economic scale on account of its food habits, and it must be remembered that in most cases the birds destroyed are much smaller than the intruder, and so of less effect in their feeding, and that two or three cowbird eggs are often deposited in one nest.

The question is a purely economic one, and until it can be shown that the young birds sacrificed for the cowbirds have more economic value than the parasite, judgment must be suspended.

THE YELLOW-HEADED BLACKBIRD.

(Xanthocephalus xanthocephalus.)

The yellow-headed blackbird is locally distributed throughout the Western United States, where it frequents marshes and sloughs, but avoids the more arid deserts, extensive forests, and wooded mountains. Its range in summer extends from southern California through northern Arizona and New Mexico to Indiana, and northward into the Canadian Provinces. It winters in the southern part of its range and on the table-lands of Mexico. Stragglers have been found from Greenland to Cuba.

Its breeding habits are much like those of the redwing, but it is usually less abundant than that bird. It is gregarious and resorts to marshes to build its nest, which is very similar to that of the redwing, and similarly placed. Although it breeds in marshes, it does not by any means confine itself to them in its search for food, but forages far afield, visiting corneribs, grainfields, and barnyards. The writer's first experience with the yellow-headed blackbird was on the prairies of Nebraska, where flocks visited the railway then in process of construction, running about among the feet of the mules and horses in search of grubs and worms exposed by the plow and scraper, and all the time uttering their striking gutteral notes (almost precisely like those of a brood of suckling pigs). In their habit of visiting barnyards and hog pastures they resemble cowbirds much more than redwings. When the breeding season is over they often visit grainfields in large flocks, and become the cause of much complaint by Western farmers.

The investigation of their food is founded upon an examination of 138 stomachs received from ten of the Mississippi Valley States, and from California and Canada, and collected during the seven months from April to October, inclusive (see p. 73). While decidedly too few to give entirely reliable results, they may furnish some preliminary

data regarding the food. As indicated by the contents of these stomachs, the food for the seven months consists of 33.7 percent of animal (insect) matter and 66.3 percent of vegetable matter. The animal food is composed chiefly of beetles, caterpillars, and grasshoppers, with a few of other orders, while the vegetable food is made up almost entirely of grain and seeds of useless plants. Predaceous beetles (Carabidae) constitute 2.8 percent of the season's food, a very small amount for a bird of such pronounced terrestrial habits. Most of these beetles are eaten in May, June, and July, and none are taken in the fall months. Other beetles amount to a little more than 5 percent, and are eaten mostly in the early part of summer. Caterpillars constitute 4.6 percent, but nearly two-thirds of them are taken in July, and in that month they form 21.5 percent of the month's food. Remains of the army worm (Leucania unipuncta) were identified in 6 stomachs. Grasshoppers are first eaten in May, but do not amount to any important percentage until July, the month of maximum consumption. In this respect this bird appears to differ, like the bobolink, from most other species, as August is usually the month in which grasshoppers are eaten most freely; but the examination of a larger number of stomachs might prove the yellowhead to be no exception to the usual rule. After August the consumption of grasshoppers is considerably increased, and the total for the season is 11.6 percent. The remainder of the animal food, 9.7 percent, is made up of other insects, chiefly Hymenoptera (ants, wasps, etc.), with a few dragonflies and an occasional spider and snail.

So far as its animal food is concerned, the yellowhead has a very good record. For a ground feeder, it takes very few predaceous beetles, while insects harmful to vegetation constitute 30 percent of its food.

The vegetable food consists almost entirely of seeds, and for economic purposes may be divided into grain and weed seed. Of grain, oats hold first place, as in the food of the redwing, and are probably eaten in every month when they can be obtained, although none were found in any of the 5 stomachs taken in September. The 3 October stomachs contained an average of 63 percent, but a greater number of stomachs would in all probability give a smaller average. August, apparently the next month of importance, shows 43.2 percent. Next to oats corn is the favorite grain, and was eaten to the extent of 9.8 percent, nearly all in the months of April, May, and June, with a maximum of 48.8 percent in April, when no wheat was eaten. Wheat appears from May to August, inclusive, and is the only vegetable food that reaches its highest mark in August. The average for the season is 3.5 percent.

Grain collectively amounts to 38.9 percent, or considerably more than half of the total vegetable food, and more than one-third of all