India, Oct. 18 -- Young tigresses first come into oestrus between twenty-eight to thirty-six months. This is when conception can happen. Male tigers can father a litter from the age of forty to fifty months. A tigress who conceives may not come into oestrus again for eighteen to twenty-two months. If conception does not take place or if a litter is lost, she will come into oestrus in one to three months. Tigers are induced ovulators-the female releases her egg only when mating has begun. The male tiger has a bone in the penis that stimulates the tigress, inducing ovulation. The penis has penile spines that induce this process and cause pain to the tigress, who roars and tries to slap the male off her. The sexual world of tigers is invisib...