THE FOOD OF BIRDS. 
243 
i 
family Elateride, the parents of the well-known 
wire-worm so destructive to corn and various 
seeds at the time of planting. 
The earth-worm, though a favorite food for 
the young bird, was found to be eaten but spar- 
ingly by the adult. After the 21st of June the 
Professor began to find strawberries, cherries, 
and other pulpy fruits, though these were still 
mixed with insects in the majority of instances; 
birds captured at a distance from gardens and 
fruit trees having less fruit and a larger num- 
ber of insects in their gizzards than those taken 
near the village, the robin not being an extens- 
ive forager. This mixed dict continued from 
the ripening of the strawberries and cherries 
until October, the vegetable portion consisting, 
during August and September, in great part of 
elder-berries and poke-berries. During the 
‘month of October the vegetable diet wholly dis- 
appeared, its place being supplied by grasshop- 
pers and other orthopterous insects. Early in 
November the robins which have passed the sum- 
_ mer among us migrate southward—the few im- 
migrants from the north, which are seen by us 
during the winter months, managing at that time 
to eke out a miserable existence upon bay-ber- 
ries, privet-berries, and juniper-berries. 
Somewhat similar in conception to the re- 
searches of Professor Jenks, though of much 
wider scope, are those to which M. Florent Pre- 
vost has devoted himself in France. As one of 
the naturalists in charge of the famous collec- 
tions at the Garden of Plants in Paris this ob- 
server has had a peculiarly good opportunity to 
study the question now under discussion. Dur- 
ing nearly thirty years he has taken pains to 
collect and preserve the contents of the stom- 
achs of all the birds which have been brought to 
the Museum, to say nothing of large numbers 
of specimens procured specially by himself and 
by the foresters of numerous public and private 
estates who have interested themselves in his 
behalf. 
It is to be regretted that the complete details 
of M. Prevost’s researches have not been pub- 
lished. As yet we have only an abstract of his 
results, and the promise of a circumstantial ac- 
count of his studies at some future day. Among 
the more note-worthy of M. Prevost’s conclu- 
sions may be mentioned the fact that the food of 
birds varies according to the age of the bird as 
well as according to the season of the year— 
the observation of Professor Jenks, that earth- 
worms are eaten by young but not by old robins, 
being evidently nothing more than the particular 
case of a general law. M. Prevost has ascer- 
tained also that the young of the greater num- 
ber of granivorous birds are really fed upon in- 
sects, and that even the adults themselves are 
insectivorous during the breeding-season. <A 
familiar instance of which we have in this coun- 
try the common chipping sparrow ; and the same 
remark applies to those species of birds which 
in early spring devour the buds and young leaves | 
of trees. It was found also that there are but 
few of the birds of prey—eren those which are 
most truly carfivorous—which do not at times 
partake of insects as food. 
The more carefully one studies the subject, 
so much the more astonishing does the place 
which is occupied by insects in the alimentation 
of birds appear. As every one knows, there 
are stated seasons of the year when certain kinds 
of insects make their appearance in large num- 
bers, and at these times it would almost seem 
that the very abundance of this food induced 
the birds to partake of it. For example, dur- 
ing the interval when the June-bug is abundant 
portions of this insect can be found in the stom- 
achs of the greater number of the birds which 
inhabit France at that season of the year; and 
the beetle in question is then found also in the 
stomachs of many quadrupeds, from the little 
shrew-mouse up to the wolf. 
M. Prevost/asserts his ability to demonstrate, 
so soon as the details of his researches are made 
public, that birds'are in general much more use- 
ful than hurtful to the husbandman, and that 
even the damage committed at certain moments 
by the grain-eaters proper is largely compen- 
sated for at other times by the consumption of 
insects by these very birds. He insists, more- 
over, upon the necessity of seeking for new 
methods of protecting those crops which are lia- 
ble to be injured by the feathered race, instead 
of resorting, as now, to the suicidal policy of 
destroying or sécking to destroy the latter. 
The influence of food in determining the vag- 
abond life which is led by many kinds of birds 
is remarkable. While some animals, without 
change of habitation, make out to obfain nour- 
ishment throughout the year by resorting to 
different kinds of food according to the season, 
others confine themselves exclusively to such 
aliments as can be obtained only under peculiar 
conditions of climate, their food being found 
only at stated periods in any one country. Now, 
in the case of quadrupeds, when a given species 
can not adapt itself to changing circumstances, 
can not obtain continuously the food suitable 
for its maintenance, hibernation is the usual 
resource: the animal simply sleeps through the 
unfavorable season. But with birds this curious 
phenomenon of hibernation does not occur—at 
least naturalists have not been able to detect 
any evidence of its existence ; not even enough 
to account for the widely-spread popular belief 
or prejudice that swallows pass the winter in the 
mud of ponds; but instead of that, and equally 
dependent upon the question of nourishment, 
we have the still more remarkable phenomenon 
of migration, when, following the calls of hun- 
ger, the feathered myriads pass to and fro over 
the countries of the earth. 
One curious point noticed by M. Prevost fur- 
nishes a remarkable contrast to the insatiable 
hunger and lack of endurance exhibited by the 
young robins of Professor Treadwell: it is, that 
some species of birds are capable, at certain 
epochs, of living for a long time without food, 
their stomachs being found to contain at these 
seasons no alimentary matter whatsoever, but 
