Estrus in the queen (female cat) is defined as the time during the reproductive cycle when she displays interest in mating. Estrus begins when the queen allows the male to mount and breed, and ends when her receptive behavior ceases. In cats, mating behavior is required to induce ovulating.
Domestic cats usually reach sexual maturity (puberty) between five to 12 months, at which time they experience their first estrus.
The adult cat is seasonally polyestrus, cycling repeatedly (about every two to three weeks) throughout the breeding season (mid-January to August), unless interrupted by pregnancy or illness. Several major phases compose the estrous cycle, and variations in the level of normal circulating hormones contribute to these different phases.