Bittern in Wikipedia

Bittern (botháurus vulgaris), a shy, solitary, wading bird related to the heron and inhabiting the recesses of swamps, where its startling, booming cry at night gives a frightening impression of desolation. In the D.V., bittern stands for Hebr. qã'ãth (Leviticus 11:18; Isaiah 34:11; Zephaniah 2:14), although by some inconsistency the same Hebrew word is rendered Deut., xiv, 17, by cormorant, and Ps. ci (Hebr., cii), 7, by pelican. The pelican meets all the requirements of all the passages where qã'ãth is mentioned, and would perhaps be a better translation than bittern.

Link: https://en.wikipedia.org/wiki/Bittern