Many riders have a distinct preference when it comes to working with mares–they either love the girls or would rather avoid them. In some cases this choice is related to hormonal behavioral changes in mares during their heat cycles. But perhaps these behavioral differences are not just related to reproduction hormones. What if there was a fundamental difference in behavior between male and female horses?

This certainly appears to be the case, according to a group of German equitation scientists.

By studying the behavior of prepubescent (not sexually mature) yearling colts and fillies, Manuela Wulf, BSc, researcher at the Graf Lehndorff Institute for Equine Science in Neustadt, and colleagues concluded that there is a definite trend towards fundamental gender differences in equine behavior–but not in the direction they had expected.

"We set out with the idea that colts were less anxious than fillies, as we know this to be the case with research on dogs and humans that show that boys are usually less anxious than girls," Wulf said during her presentation at the 2011 International Society for Equitation Science Conference, held Oct. 26-29 in Hooge Mierde, The Netherlands. "But what we found was that … (our study) colts are definitely not less anxious than (our study) fillies."

For her study, Wulf employed six male and nine female Warmblood yearlings raised in identical conditions. Once daily for five days the young horses were brought into an arena alone with a previously unknown human. The human would stand motionless for a short period of time (five minutes the first day and one minute t