LONDON - Edinburgh Zoo says there are signs that one of its giant pandas may be pregnant.
The zoo says nesting behaviour and changes in hormone levels suggest Tian Tian could be expecting a cub -- or experiencing a phantom pregnancy, not uncommon in pandas.
The zoo said Friday that the signs "give us cause for encouragement," although Tian Tian has not co-operated with an ultrasound that could yield more information.
If pregnant, she should give birth in late August or early September.
Giant pandas have difficulty breeding, and none has ever been born in Britain.
The zoo artificially inseminated Tian Tian, or Sweetie, after she was reluctant to mate with male companion Yang Guang, or Sunshine.
