In the female snow leopards, the increase in oestrogen level in the winter season is associated with the increasing frequencies of the sexual behaviors.(Schmidt et al, 1993)(Figure 10)The evolutionary advantage behind this is that in the summer the food resources are more abundant, thus increasing the survival chance of the cubs by the time they were born.The mean gestation period of snow leopards is around 102 days, and the mean litter size is 2-3 cubs, with the female being the only one taking care of the offspring(Wharton and Mainka, 1997). The cubs were around 11.30z-20oz were born, and they would be able to open their eyes after seven days,  leaving the den after they were born for four months(Sunquist, 2002). However, the snow leopards won’t be completely independent. The initial separation between cubs and their mothers appeared when they were 20-22 months old, which could be triggered by the coming of next mating seasons and the presence of other male snow leopards, as well as the increasing energy cost of hunting for large size cubs. The separation between male cubs with mother might be earlier than female cubs, for the reason that adult males and females are more tolerant towards female cubs in their territory(Johansson et al, 2020). The snow leopards reach sexual maturity at age of two, and they can normally live up to 15 years in the wild.