Comparison of hormone profiles for singleton and twin births in a female giant panda.

The breeding of giant pandas is inherently difficult owing to the short oestrous cycles of the females. Determining the exact time of the oestrous cycle and when the females will attempt to mate may increase the chances of reproductive success. Because the female giant panda at the Everland zoo in Korea did not show signs of oestrus in 2019, her oestrous cycle could not be measured. In 2020, we induced oestrous behaviour in the same panda, used oestrogen peak and trough levels to predict her ovulation period, and two natural mating attempts were conducted in two days. We confirmed and monitored the pregnancy using progesterone measurements and ultrasonography, respectively, and the female successfully delivered and raised a single cub. In 2023, the same method was used on the female, with repeated success. Her urine showed a sharp increase in progesterone levels, unlike in 2020, indicating she was pregnant with twins, which she successfully gave birth to in July 2023. Herein, we share our findings on these giant pandas and the potential application of our methods to other endangered animals like rhinoceros and red pandas.