The buller syndrome in American bison bulls

Abstract

Homosexual mounting (buller syndrome) was observed incidentally during approximately 3900 h of field observations of 2 populations of American bison (Bison bison) in the course of an 11-year study of social and reproductive behaviour. Buller behaviour was regularly observed in intact, free-ranging males up to the age of 4 years. This suggests that some level of this behaviour, which is an economically significant problem in cattle husbandry, may be a natural trait of feed-lot steers.