Elephant

Elephant calves
Female elephant social life revolves around breeding and raising of the calves. A female will usually be ready to breed around the age of thirteen, when she comes into estrus, a short phase of receptiveness lasting a couple of days, for the first time. Females announce their estrus with smell signals and special calls.
Females prefer bigger, stronger, and, most importantly, older males. Such a reproductive strategy tends to increase their offspring's chances of survival.