Some Common Birds in Their Relation to AgricultureBeal, F. E. L. (Foster Ellenborough Lascelles)
Science
Some Common Birds in Their Relation to Agriculture
Beal, F. E. L. (Foster Ellenborough Lascelles)
Birds -- United States
In an investigation of the food of the blue jay 292 stomachs were
examined, which showed that animal matter comprised 24 per cent and
vegetable matter 70 per cent of the bird's diet. So much has been said
about the nest robbing habits of the jay that special search was made
for traces of birds or birds' eggs in the stomachs, with the result that
shells of small birds' eggs were found in three and the remains of young
birds in only two stomachs. Such negative evidence is not sufficient to
controvert the great mass of testimony upon this point, but it shows that
the habit is not so prevalent as has been believed. Besides birds and
their eggs, the jay eats mice, fish, salamanders, snails, and crustaceans,
which altogether constitute but little more than 1 per cent of its diet.
The insect food is made up of beetles, grasshoppers, caterpillars, and
a few species of other orders, all noxious, except some 3½ per cent of
predaceous beetles. Thus something more than 19 per cent of the whole food
consists of harmful insects. In August the jay, like many other birds,
turns its attention to grasshoppers, which constitute nearly one-fifth of
its food during that month. At this time, also, most of the other noxious
insects, including caterpillars, are consumed, though beetles are eaten
chiefly in spring.
The vegetable food is quite varied, but the item of most interest is
grain. Corn was found in 70 stomachs, wheat in 8, and oats in 2--all
constituting 19 per cent of the total food. Corn is evidently the favorite
grain, but a closer inspection of the record shows that the greater part
was eaten during the first five months of the year, and that very little
was taken after May, even in harvest time, when it is abundant. This
indicates that most of the corn is gleaned from the fields after harvest,
except what is stolen from cribs or gathered in May at planting time.
The jay's favorite food is mast (i. e., acorns, chestnuts, chinquapins,
etc.), which was found in 158 of the 292 stomachs and amounted to more
than 42 per cent of the whole food. In September corn formed 15 and mast
35 per cent, while in October, November, and December corn dropped to
an almost inappreciable quantity and mast amounted to 64, 82, and 83
per cent, respectively. And yet in these months corn is abundant and
everywhere easily accessible. The other elements of food consist of a few
seeds and wild fruits, among which grapes and blackberries predominate.
The results of the stomach examination show, (1) that the jay eats many
noxious insects; (2) that its habit of robbing the nests of other birds is
much less common, than has been asserted; and (3) that it does little harm
to agriculture, since all but a small amount of the corn eaten is waste
grain.
THE CROW.
(_Corvus americanus._)
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