Notes:
The next morphological change is in the vulva (which is being captured by photographs and rated quantitatively). The vulva becomes enlarged, red and swollen. In giant panda, the vulva is completely closed outside of breeding season, but opens at peak of estrous. In other bears, the vulva is open outside of breeding season, so you can expect degree of swelling and coloration to change. We did see opening of vulva in immature bears, but not other characteristics.