About 80 percent of mares give birth at night. Thought to be the result of evolution, this survival mechanism meant that a mare would give birth near the herd that was settled for the night, instead of near one traveling in daytime. Survival is also the reason that mares usually give birth quickly, with a first-stage labor of two to four hours and the actual birth usually completed within an hour. The foal can stand and walk within minutes of birth because, in the wild, both mare and foal must be ready quickly to travel on with the herd...