More than a third of Greater Wester Sydney's membership base support another AFL team, a survey conducted by the club has found, but Giants chairman Tony Shepherd says this should be seen as an endorsement for expansion.

Four of the Giants' five strongest regions are in the club's so-called heartland in western Sydney while 45 per cent of respondents said they or their parents did not follow the code before the Giants' arrival, the research found. The questionnaire also showed 52 per cent of their members have never played the game at any level.

Shepherd said that he initially found it "strange" that for 36 per cent of Giants members the club was not their No.1 AFL team. Of this group, 10 per cent said they have switched from cross-town rival the Swans while another 5 per cent have left other clubs.

"I did find it strange at the start then you talk to people and a lot of people, particularly AFL followers, really welcome expansion in Sydney and the ACT," Shepherd, formerly a Geelong fan, said.