they sink, but the moon is now becoming luminous, and the swish and 'coo-ee, hook-a-coo-ee' of peewits is about one on one's way back, over the heath."
I will conclude this fragment of my rook diary by giving a list of some of the distinct notes or sounds which I have, at different times, heard the birds utter. It is but a small page out of their vocabulary, but it may, perhaps, serve to draw attention to the great powers of modulation and inflexion which these birds possess. I must confess that the way in which the voice of the rook is usually spoken of makes me wonder. To me it has often seemed as though these birds were really in process of evolving a language. In only a few cases, however, have I been able—or have I thought myself able—to connect a note with any particular act or state of mind. Here is the list:
Caw (the ordinary "caw" more or less).
Chĭ-choo, chĭ-choo, chĭ-choo.
Cha.
Chug-a, chug-a, chug-a.
Chug-chaw.
Chack-a, chack-a.
Choo (very prolonged).
Chuck (loud, clear, and distinct).
Chee-ow (very lengthened).
Hă-chă ("a" as in "hat").
Har-char.
How-chow, or chow-how.
Hoo, hoo.
Hook-a-hoo.
Hook-a-hoo-loo.
