When asked about the possibility of sterilization, Holst said, "If we just sterilize him, he will take up space for more genetically valuable giraffes."
The EAZA supports for the zoo's decision, according to Jörg Jebram, who oversees the European endangered species program for giraffes. Jebram explained that because giraffe groups are often made up of one male and several females, Marius could not stay with his group, for fear of inbreeding.
Females are normally moved to a new breeding group when they are old enough. Bulls are sent to zoos that keep a bachelor group. When there are no females present, males can co-exist peacefully. In this case, there were no acceptable openings. Historically, many of the 347 zoos that belong to the Amsterdam-based European Association of Zoos and Aquaria (EAZA) were eager to have giraffes of any kind. But in the past several years zoo breeding programs have produced enough of some subspecies.
The Copenhagen Zoo received two offers from other zoos willing to take Marius, but said that one already had an ample supply of Marius's genetic line, and the other offered no guarantee that Marius would not later be sold elsewhere.