William J. Long,
How animals talk
(1919)
“ The simplest or most obvious method of animal communication is by inarticulate cries, expressive of hunger, loneliness, anger, pleasure, and other primal needs or emotions. The wild creatures are mostly silent, and so is the bulk of their “talk,” I think; but they frequently raise their voice in the morning or evening twilight, and by observing them attentively at such a time you may measure the effect of their so-called language. Thus, you see plainly that to one call the animal cocks his ear and gives answer; at another call he becomes wildly excited ”
