128 Bird - Lore
own eggs. as yet unhatched: a Loon which voluntarily risked his life to- free a Piedvbilled Grebe from a nearly fatal ice-trap: and a Great Crowned Pigeon which assumed the care of and sheltered a nestling Ring Dove deserted by its parents.
Another aspect of the mental processes of birds shows us examples of revenge being taken after long and patient waiting for a favorable op- portunity, while. on the other hand. Crows have been known again and again to sit in judgment upon one of their number, and to sentence and punish it with death.
The language of birds is most complex. and all. frotn the marvelous song of the Nightingale and the imitative powers of the Mockingvbird. to the many moods and feelings reflected in the apparently meaningless chirps of our city Sparrows, tell of mental powers striving for expression.
In man, the various emotions depend upon language and the range of expression of the face for their outward demonstration, and it is interest- ing to compare with this the state of afiairs among birds. These crea- tures, handicapped by a vocal language very inferior to our own, and faces. for the most part sheathed, like those of insects, in expressionless masks of horn, yet are able by movements of their feathers, limbs, and other portions of the body, to express a wide range of emotions, and to- clearly communicate even delicate shades of meaning.
Interrupting, for a tnoment. the mention of these finer qualities which show the high mental position of birds, it is desirable to emphasize a factor common to all animals, but which in birds is very important. and developed to a remarkable degree that of extreme individuality. It is to (his plasticity or wide variation on the already high level of knowledge, or "platform of determination," as Baldwin happily terms it, that gives to- birds the numerous chances for new affillt’nffl/ oppor/unilier, as we may call them—stepping-stones on the road of deduction. to some new and higher expression of psychic power. Every-day accidents in the search for food may be instantly seized upon by the quick perception of birds. and turned to good account.
Birds had early learned to take clams or muscles in their beaks or claws at low tide. and carrv them out of the reach of the water, so that at the death of the mollusk the relaxation of the adductor muscle would permit the shell to spring open and afford easy access to the inmate. Probably' it needed only the accidental dropping of a few shells on the hard rocks, and a taste of the appetizng morsels within. to fix the habit which, by imitation. has spread so widely among birds at the present day. To how trivial an accident might the beginnings. the psychic milaga, of many modern cosmopolitan traits of birds be traced if we could but read the past clearlv!
Play and courtship—while they go hand-in»hand. so to speak—afford
