Who, by a mere glance, could imagine the materials that the little bird called the vireo employs in building her peculiar nest? The reader will remember how we pulled one of those nests apart, and what strange materials we found woven in its fabric.[2] But they were hardly more surprising than we may discover within this sly cocoon if we dissect it. Now, to begin with, a true cocoon is not solid to the core, as this one evidently is as we press it between our fingers, nor can you pinch off a tuft of gray hair from the surface of an ordinary cocoon when you will. True, there are some cocoons into whose silk meshes the caterpillar weaves the hair of its body, but the felt thus formed is only a shell, and is intermeshed with silken webs, and one pinch alone will open up the hollow interior and show us the caterpillar or chrysalis within. Such, for instance, is the little brown winter snuggery of the woolly-bear caterpillar which we all know, and whose prickly cocoons may be found beneath stones and logs in the fields.
[2] See "Sharp Eyes," page 220.
But what do we find in these cocoons that we now have before us? Not only is there no vestige of silk to be seen, but there are hairs enough in this single cocoon to have supplied a hundred caterpillars, while we look in vain for any sign of the spinner within. Indeed, there is no within; pinch after pinch reveals nothing but the same gray felt. We are now a quarter of an inch below the surface, when another pinch brings with it a small mass of white specks like crumbs intermingled with the hair, and in the hollow thus deepened we observe a shiny white object like ivory, with a minute ball at its tip. It certainly looks like a tiny bone. We impatiently break open the cocoon, when we see in truth a bone—indeed, a compact mass of bones from some very small animal, whose identity we may guess from the mouse-color of the felt. Here is the femur of a field-mouse—two of them—also a part of the fibula, and a dozen or more other bones. Breaking asunder the mass further, we find a few tiny teeth; and as we continue the process in the remaining two specimens, we bring to light parts of the skull, ribs, and vertebræ. A strange "cocoon" indeed.
A further examination of the remaining specimens disclosed similar ingredients, until the entire mass presented a collection somewhat like that shown in my illustration.
I well remember my first encounter with the queer specimens, and what mysteries they were, though the "cocoon" idea had never suggested itself to me, the felted mass having been found in a disintegrated state.
It was on a winter's day, in a walk on the crusted snow, during my early boyhood. Returning by the brink of a stream, I noticed a little gray mass of fur on the snow, which on examination disclosed numerous bones of what I took to be field-mice and parts of the anatomy of a mole intermingled with the hair. No vestige of flesh appeared in the mass, and I fell to wondering what manner of disease is this with which the mouse world is afflicted that should consume the flesh and leave nothing but a disjointed skeleton and a tiny pile of fur. Ah, had I only known then what I discovered a year or two later—the secret of that big hollow in the willow-tree above—my little pile of fur and bones would easily have been explained, for there summer after summer sat the little brown screech-owl, blinking in the sun at her doorway, peeping through the tiny cracks of her closed eyelids at noon, and at midnight commanding a view of the entire surrounding sedgy swamp in her eager quest for the first unfortunate shrew or deer-mouse that should peep its nose out of its nest or venture across the ice in the field of her staring vision.
The new-fallen snow would doubtless show as many telltales of midnight tragedies among the little bead-eyed folk—the tiny trail terminating in a drop of blood, and a suggestive ruffling of the surrounding snow, with its plain witness of the fatal swoop of "owl on muffled wing" from its vantage-ground here in the willow-tree. To-night our little deer-mouse ventured too far from its nest among the tussocks. To-morrow night all that will be left of its sprightly squeaking identity will be a tiny pile of fur and bones disgorged in the form of pellets from the open beak of the owl on the willow-tree.
In regard to these specimen pellets which my correspondent has sent to me for identification, I am not prepared to affirm that they are from the digestive laboratory of the owl. Something in their size suggests that a hawk is equally likely to be responsible for them, all the birds of prey having this same singular habit of ejecting the indigestible portions of animals which they devour. A pet red-tailed hawk which I kept during the past summer littered its pen with pellets of a similar size and consistency to these, varied on one occasion with a number composed entirely of grass, which explained a singular puzzle of the day previous, when I descried my hawk with its craw largely distended, and wondered what squirrel or chipmonk or snake had been thus caught napping in my absence.