H. P. Blavatsky

Kalavingka. “The sweet‐ voiced bird of immortality “. Eitel identifies it with cuculus melanoleicus, though the bird itself is allegorical and non‐existent. Its voice is heard at a certain stage of Dhyana in Yoga practice. It is said to have awakened King Bimbisara and thus saved him from the sting of a cobra. In its esoteric meaning this sweet‐voiced bird is our Higher Ego.

Source: H. P. Blavatsky, The Theosophical Glossary, art. Kalavingka