Q: I've noticed that when horses at my boarding barn are turned out together, the geldings will frolic and play with each other, but the mares never seem to. Is this a valid observation and, if so, what's behind it?
A: Even we scientists have noticed that—in the horse world at least—boys seem to have more "fun" than girls. Although it's anthropomorphizing to assume that horses enjoy the activities that look playful to us, animal behaviorists have defined and studied equine playlike behavior: object play (e.g., nibbling, chewing, pawing), locomotor play (e.g., running, bucking, chasing), play sexual behavior and play fighting. And we have observed males doing these behaviors more than females, both in domestic situations and in more natural conditions.
This dichotomy begins at an early age, when both fillies and colts play, but colts spend a little more time playing. Puberty changes things even more dramatically. Once a filly begins to ovulate—in the spring of either her yearling or 2-year-old year—she cuts back substantially on her playtime. From that point on, she spends most of her time eating, resting and nursing foals.
Mature stallions, on the other hand, continue to play. Bachelor stallions (stallions living on their own or with other stallions), particularly, spend a great deal of time playing. Harem stallions (actively breeding stallions associated with a harem of mares) play less than bachelors, but it's not unusual to see them "horsing around" with youngsters.
Animal behaviorists use classical reasons to explain these observations. As with many species, play is believed to help teach young horses the rules of society: what's too much physical contact, who's in charge and so on. It also develops physical skills and, in mature animals, helps to maintain fitness and athletic ability. In the wild, this conditioning is much more important to stallions, whose job it is to defend the herd from intruders—other stallions and predators. Muted fighting behavior, in essence, keeps them in practice.
Mares, on the other hand, have a different purpose in life: providing food for their fetuses and foals. They seem to focus more on energy conservation (to produce healthy babies and milk) than physical conditioning. In response to a threat, they usually form a circle or semi-circle around their young, with their tails pointing out toward the threat—leaving more aggressive fighting up to the stallions.
In more natural conditions, mares even seem to leave the parenting up to the stallions. After foals are about 10 days old, harem stallions do the primary parenting, such as retrieving the foals when they wander off and entertaining them when they're bored. They're much like a human dad who plays rough-and-tumble on the living room floor on a Sunday afternoon while mom's doing the dishes.
Certified Applied Animal Behaviorist Sue McDonnell, PhD, has spent 13 years studying a semi-feral herd of ponies on the New Bolton Center campus of the University of Pennsylvania School of Veterinary Medicine. A leader in her field, she published the book A Practical Field Guide to Horse Behavior in 2003. Sue's specialty is stallion behavior.
This article originally appeared in the March 2007 issue of Practical Horseman magazine. Read more from Dr. McDonnell in the July 2012 issue.