Ovulation is when a female is fertile. She can only conceive during this time, which usually occurs around day 14 of her cycle. Mammals ovulate, but only humans and apes menstruate. The difference is that animals such as horses, pigs and dogs, work on an estrous cycle, not a menstrual cycle.
The primary difference is that they are only in heat at certain times of the year. It is only during this period that they are sexually active. Female humans, however, can be sexually active at any time. Alas, with great freedom comes great responsibility. The reason female humans menstruate is that the endometrium, the uterine lining, is shed, while in the estrous cycle it is reabsorbed. In both humans and cats, a bloody discharge is expelled, although in cats, it’s technically not menstruation since a different process is taking place. When cats and other estrous cycle animals are in heat, it is pretty clear. In humans, however, signs of ovulation are not readily discernible by others, although it is proved that women are more sexually active and have more sexual thoughts during this time of their cycle. Women are said to make their facial features more attractive while they are ovulating. But otherwise, in distinction from the animals, humans are said to have a concealed ovulation.