other species Where would the bird find material for its song if not through hearing it? New phrases in the human language are made up of old words, and the same thing holds in bird song. It would be impossible for a bird to "invent" or "originate" a song. But all of this is too obvious to require discussion. Tlie elements of bird song must have pre-existed; they must have been first heard and then reproduced. In their ultimate analysis they must have been physical, derived from insensate sources and inanimate features of earth and the ele- ments, or the involuntary and accidental movements of primitive voiceless things, animal or vegetable. But all of this is "another story" for which see Witchell (pp. 181-186). Coming back to what Witchell calls (p. 177) "that imitative tendency which is latent if not evident, in nearly every bird with any pretensions to a song"—let us ask again: What does song imitation (or elaboration) mean (if anything) in the social economy of bird life?
If the bird is in no wise responsible for anything that he does but is sus- tained in all acts by an ultimate cause, then it is perhaps vain to look for the meaning in his behavior. But if we conceive that the bird displays some con- sciousness of its own behavior, some intelligence of its own (even though it be a mere image of the greater intelligence, an effect worshipfully endeavoring to ape its cause) then we can at least observe the behavior of this "image" and come to some conclusion as to what it is trying to do and why. If we form some estimate of the bird's apparent intelligence, as we see it at work, we may gain a hint as to the true purpose that is being expressed.or reflected therein.
To take an example of imitation in its most striking manifestation, let us turn for a few moments from the Brown Towhee to the Mockingbird This bird, according to Lloyd Morgan (p. 193) represents a stage of "intelligent imitation, arising in close connection with interest in the doings of others
. .". The three stages (as illustrated by the human child) are, "First, the
instinctive stage, where the sound which falls upon the ear is a stimulus to the motor-mechanism of sound production. Secondly, the intelligent stage of the profiting by chance experience .... If we assume that the resemblance of the sounds he utters to the sounds he hears is itself a source of pleasurable satisfac- tion (and this certainly seems to be the ease), intelligence, without the aid of any higher faculty, will secure accommodation and render imitation more and more perfect. And this appears to be the stage reached by the mockingbird or parrot. But the child soon goes farther. He reflects upon the results he has reached .... ". Professor Morgan adds that "of intentional and reflective imitation there is at present no satisfactory evidence in any animal below man"
Let us examine a typical song of the Mockingbird (Mimus polyglottos leucopterus), one recorded by me in the San Joaquin Valley, near Mendots, Fresno County, California, June 20, 1918. During a period of listening I recorded eleven "original" or un-imitated and nine imitated parts. The imitated parts, rendered in a manner that ranged from fair to perfect, were unmistakably referable to the following birds: Traill Flycatcher, English Sparrow, Western Belted Kingfisher, Ash-throated Flycatcher, Sparrow Hawk, California Cuckoo, California Shrike, Red-shafted Flicker, and Killdeer—all, by the way, birds present in the habitat of this individual Mocker. In addition to these notes the bird uttered several others which suggested the notes of other species without being quite enough like them to be fairly called imitations.
Whenever I hear a Mockingbird sing I cannot help wondering just where, if anywhere, the line can be drawn between the second and the third stage de-
