Social relations in a mixed group of mules, ponies and donkeys reflect differences in equid type

► Domestic equids are often housed together as a homogenous group. ► Social relations in a herd of 16 domestic horses, donkeys and mules were observed. ► Subjects associated with individuals of the same equid type as themselves. ► Dominance rank and linearity of hierarchy varied according to equid type. ► Differences may be based on the ecology of their wild ancestors.