On 15 August 2019, a square-lipped rhinoceros calf was born at Royal Burgers’ Zoo. The young bull looks to be in good health. Since 2002, the Arnhem zoo has been remarkably successful at breeding rhinoceros: as many as ten rhinoceros have been born in the capital of the province of Gelderland, including one stillbirth. A total of 269 square-lipped rhinoceros live in European zoos, 116 bulls and 153 cows. On average, only ten square-lipped rhinoceros are born each year in Europe.
Not all adult bulls are fertile, and rhinoceros cows often develop cysts in the uterine horns. As a result, the sperm can no longer reach the egg, or the egg cannot come loose from the ovary. The cysts can also block the egg from passing through the fallopian tube, or the fertilised egg from nestling in the uterine wall. Young cows being hormonally suppressed by their mothers is another problem zoos face. In this situation, the young cows only become fertile after being transferred to another zoo, which lifts the oppression.
Of the five rhinoceros species alive today, the square-lipped rhinoceros has the most social behaviour. Whereas the other four rhinoceros species live in solitude and only temporarily visit each other during mating season, square-lipped rhinoceros live in small herds of adult cows and their young. As a rule, the cows in these herds are closely related. The bulls live alone and demarcate their territory by depositing dung piles along the borders as scent flags.
To ensure successful breeding of square-lipped rhinoceros, it is beneficial, given their natural behaviour and social group structure, for the animals to have plenty of space at their disposal, so that they can avoid each other or, on the contrary, visit each other. In Arnhem, the breeding bull lives a more or less solitary life, usually avoiding the company of the cows and their young. In the mating season, the bull will seek contact. Burgers’ Zoo has a fertile bull and two cows, both of which have given birth multiple times.