Background

According to Jeremy Black:

"Bau was a goddess worshipped almost exclusively
at Lagaš, where she was regarded as the
spouse of the god Ningirsu, or else of Zababa.
Numerous records survive of the offerings
made in the E-tarsirsir, her temples at Lagaš
and Girsu, where oracles were given in Early
Dynastic times. Bau was a daughter of An, and
had two sons by Ningirsu, the deities Ig-alima
and Sul-šagana, as well as seven daughters
(minor goddesses of Lagaš) for whom
Ningirsu's paternity was not claimed.
Formerly the goose was thought to be the
bird associated with Bau, but this is now known
to be erroneous. On Babylonian kudurrus
Bau is represented by an object which has been
thought to be a winnowing fan.
It is possible that the correct form of the
name is Baba." ^[1]

In any case, Bau was an older deity.