Original: Mating is the term most often used to refer to sexual intercourse between animals other than humans ; for most , mating occurs at the point of estrus ( the most fertile period of time in the female 's reproductive cycle ) , which increases the chances of successful impregnation .
Simplified: Sexual intercourse between animals other than humans is often called mating . Most animals only mate when the female is at the point of estrus , which is the most fertile period of time in its reproductive cycle .