The pair and five others join the retiring Robert Harvey and Fraser Gehrig on the list of departures from Moorabbin.
Matthew Ferguson, Michael Rix, Birss and Gardiner have all been cut while Jayden Attard, Glenn Chivers and Luke van Rheenan have been dropped from the rookie list.
Gardiner and Birss can consider themselves extremely unlucky having played 12 and eight games this year respectively.
Gardiner arrived at the Saints in last week’s trade week as part of the deal that also saw Steven King move from Geelong to St Kilda.
Birss came to the Saints from the Western Bulldogs the season before and managed 20 games in the red, white and black.
Attard missed this season because of a knee reconstruction but played 20 games in 2007 after crossing over from the Brisbane Lions.
Ferguson played 12 games for the Saints and Rix played 29.
Matthew Drain, St Kilda’s GM Football – List Management paid tribute to the nine departing Saints,
“We’d sincerely like to thank all nine guys for their commitment and contribution to the Club and wish them all the best in their future endeavors,” Drain said.
