In those mammals which are seasonal breeder, the females are receptive only once in a year ; the cycle is termed as:

Estrous: It is cyclical period of sexual activity in non human female mammals, marked by congestion of and secretion by the uterine mucosa, proliferation of vaginal epithelium, swelling of the vulva, ovulation, and acceptance of the male by the female. During estrus, the animal is said to be "in heat".