"They once darkened the skies of Xindus."

- Jannar

"My grandfather lived there. There were times when he recalled the sky was filled with Avians."

- Gralik Durr

The Xindi-Avian species was an extinct member of the Xindi race, wiped out during the conflict between the six Xindi species which destroyed their homeworld, sometime in the 2030s. Due to their primitive technology, the Avians were incapable of leaving Xindus and so were wiped out.

Gralik Durr's grandfather, who had resided on Xindus, remembered a time before the planet's destruction when Avians would flock overhead, filling the sky. (ENT: "The Shipment")

Strangely, the remains of an Avian settlement were found on a planet that dated back to the 2nd millennium BC. The ruins of the settlement were used for the meeting place of the Xindi Council. (ENT: "The Council")

A skull of an Avian was kept at the Council's location. Commander Dolim commented that the Council chamber had "the stench of the Avians' failure to survive". (ENT: "The Council")