Zoos on both sides of the Atlantic have limited space, and with their space limitations, they share a goal of controlling the size of their captive populations. But they have vastly different approaches to the issue. While many zoos in North America use contraception to control their animal populations, their European counterparts do not, even if that means they produce extra animals. Instead, the European zoos prefer that their animals get to experience giving birth and raising their young. To control the population, excess animals are then culled.