It's kind of hard to tell from the pic. Using the pic as a guide, bring your left thumb further back to just immediately in front of the opening. GENTLY but firmly press down. A female will have a long slit; a male has a shorter one or a circle. If it looks slightly circular, pushing down a little more, pulling the skin tighter might reveal a penis.
Is there a reason this has to be a female? Is it a pet or for show or ?? After checking this last time, I would leave it's hiney alone for awhile. All of the pushing, prodding, squeezing is uncomfortable and can cause subcutaneous bruising. It could cause him/her to react violently to being held in this position, a position that is vital to the care and upkeep of your bun.
