The United Nations ' Food and Agricultural Organization list the Kaimanawa horses as a herd of special genetic value that can be compared with other groups of feral horses such as New Forest ponies , Assateague ponies , wild Mustangs , and with free @-@ living zebras . Kaimanawas are of special value because of their low rate of interaction with humans . This lack of interaction may result in a herd with more wild and fewer domestic characteristics , which is of special interest to researchers . Between 1994 and 1997 , students from Massey University studied a population of around 400 Kaimanawa horses to learn their habits and herd dynamics . A 2000 study found that although sometimes there are more than two stallions in Kaimanawa horse herds , only the two stallions highest in the herd hierarchy mate with the herd females . This differ from other feral horse herds , some of which have only one stallion that mate with mares , while others have several stallions that sire foals .