NOTES ON THE GIZZARD CONTENTS OF BIRDS. 143
the bird hovering over such a spot? He suddenly descends and
swoops on his prey. The experts tell us that his staple food
is mice, voles and beetles. But this time his prey consists of more
slippery fare—it is a large slow worm. How do we know this?
Because not only was a chunk of slow worm found intact
with the pellets, but wrapped up in them were the rounded
scales, bony plates and vertebrae of the same reptile, showing
that the bird had really digested a portion of the creature. In
the same pellets maybe seen:—The fur of a vole, of a mouse, of a
bat. Some powdery lumps consist of the jointed hairs of a bat's
fur. There are two vole skulls, one rat skull, two bird skulls, a
small lizard, almost entire, a land snail (Zonites cellarius) and the
iridescent blue and green elytra of beetles.
This is not a bad record of a varied diet!
To return to the slow worm. He may be recognised, even if
all his bones are comminuted, by means of the presence of in-
numerable bony plates in the matrix. The slow worm is a lizard
rather than a snake. It is the only British representative of
the Family of Lizards known as the Scincidoe, which are char-
acterized by possessing a rigidity of body not found in
other lizards or in snakes. This feature is due to the presence
of a framework of bony plates below the scales; each plate has a
scale attached to it. In examining the food of the Magpie in
Mr. Christy's collection, the bony plates and scales of a small
slow worm were discovered and identified from the presence of
these plates.
Another specially interesting component of the kestrel's
pellets was furnished by the hairs of the bat. These when once
seen are unmistakable. I learned them first in the pellet of a Little
Owl. Bone-like fragments in the powder of a pellet afforded a
problem, and I examined the hairs of many spiders and insects
in vain, till at last a hair was found in a pellet that had escaped
comminution. With Miss Lister's help the fragments proved
to be the broken hairs of a bat. Powdery lumps in the kestrel's
pellet have a similar origin. Mr. Witherby, in the Practical
Handbook of British Birds, says of the kestrel's food:—"Quite
exceptionally bats."
In the pellets of the Barn Owls from six localities, the pre-
dominating food traces are those of shrews, voles, mice and
sparrows, though there are also remnants of bats and beetles.