What bird is on the Egyptian flag?

Several different types of bird had religious significance because of their association with gods and goddesses.

The ibis (hieroglyphs: gmwt, black ibis; hby, white ibis) was sacred to the god Thoth, who is sometimes shown with the head of an ibis.

The hawk (hieroglyphs tnHr) was a symbol of both Horus and Montu, two gods connected with the sun.

Both ibis and hawks were sometimes mummified.