BIRD PELLETS—EVIDENCE AS TO FOOD OF BIRDS. 117
Even among invertebrate animals it would seem that the
pellet-casting habit is not entirely unknown. That most careful
observer, Henri Fabre, in his account of the Garden Spiders,
describes the feeding methods of a species of Epeira (E. fasciata),
which he had watched overnight engaged in sucking the body-
juices of a captured locust, in these words: "Next morning
the spider is still at table. I take away her dish. Naught
remains of the locust but his skin, hardly altered in shape,
but utterly drained and perforated in several places. The
method, therefore, was changed during the night. To extract
the non-fluent residue, the viscera and muscles, the stiff cuticle
had to be tapped here, there and elsewhere, after which the
tattered husk, placed bodily in the press of the mandibles,
would have been chewed and finally reduced to a pill, which
the sated spider throws up. This would have been the end of
the victim, had I not taken it away before the time."
In the case of birds, few observers seem to be able to afford
any definite information as to which birds, or how many, possess
this habit. When, some three years ago, I made enquiry of
ornithological acquaintances (some of them first-class authori-
ties in bird-lore) on this point, the replies showed that com-
paratively little first hand observation had been made in this
regard; it was generally known that birds of prey possessed this
enviable faculty of avoiding attacks of indigestion, and that
it was shared also by such birds as rooks, shrikes, herons and
gulls: but the authorities questioned appeared scarcely to be
aware how considerable a proportion of birds is accustomed to
get rid of non-assimilable portions of food in this way.
As a matter of fact, a large number of birds, of very diverse
orders, cast up pellets. It is almost certain that all birds which,
regularly or occasionally, swallow indigestible matters, such as
the husks of plant seeds, the hard parts of insects, the bones of
fish or birds, and the bones and fur of mammals, are compelled
to adopt this method of getting rid of such matters.
The food of birds necessarily varies considerably at different
seasons, or is dependent upon chance conditions, consequently
pellets will be more likely to be produced at seasons when the
food includes indigestible substances; for example, Rooks
in spring eat the roots of twitch-grass and newly sown oats,
the remains of which appear in their numerous castings at