Ibis Worship. The Ibis, in Egyptian Hab, was sacred to Thoth at Hermopolis. It was called the messenger of Osiris, for it is the symbol of Wisdom, Discrimination, and Purity, as it loathes water if it is the least impure. Its usefulness in devouring the eggs of the crocodiles and serpents was great, and its credentials for divine honours as a symbol were: (a) its black wings, which related it to primeval darkness—chaos; and (b) the triangular shape of them—the triangle being the first geometrical figure and a symbol of the trinitarian mystery. To this day the Ibis is a sacred bird with some tribes of Kopts who live along the Nile.
Source: H.P.Blavatsky - The Theosophical Glossary