Bird will replace the retiring Argentinian Patricio Albacete.
Bird is currently in his fifth year of Super Rugby after making his debut with the Crusaders in 2013.
He moved north to join the Chiefs in 2016, and his form for the side saw him re-selected for the All Blacks at the end of 2017.
Unfortunately the 2.06m lock had his 2018 campaign cut short after suffering a shoulder injury during the first game of the Super Rugby season.
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Fellow new signings Volavola and Raphael Lagarde will likely battle to back up Scottish international Russell, with all three new fly-halves joining the club after the departures of Daniel Carter and Remi Tales. The club will also be without the recently re-signed Patrick Lambie for an extended period after the Springbok suffered a serious knee injury during the recent Champions cup final at Bilbao.