Hopes of Adelaide Zoo's giant panda Fu Ni giving birth this year have been dashed.
Keepers have been treating her as if she was pregnant since she was artificially inseminated in September but say the period for when she would have delivered a baby has now passed.
They say hormonal changes and her behaviour suggest Fu Ni has experienced a "pseudo pregnancy".
"During a pseudo pregnancy, hormonal changes and behaviours are identical to those of a true pregnancy, making it very difficult to determine if a Giant Panda is actually pregnant or not," Zoo SA Senior Keeper Jaimee Foote said.
It is Fu Ni and partner Wang Wang's fourth attempt at breeding and the Zoo's Chief Executive Elaine Bensted said they remain hopeful to try again.
"We have always known that breeding the Southern Hemisphere's only Giant Pandas was going to be incredibly challenging," Ms Bensted said.
Wang Wang and Fu Ni have been at Adelaide Zoo on loan from China since 2009.
