Hippopotamuses are semi-aquatic mammals with complex social and environmental needs that are challenging to meet in zoological collections. Their welfare in captivity deserves greater attention as understanding of hippo behavior grows.
Zoo hippos face welfare challenges rooted in their semi-aquatic nature. Their skin requires prolonged water immersion to prevent cracking and infection - hippos without adequate water access develop painful skin lesions. The social nature of hippos means that isolated individuals or pairs represent impoverished social environments. Male hippos are highly territorial and can seriously injure or kill conspecifics in cramped conditions, creating welfare problems from both isolation and inappropriate social grouping. Many zoo pools lack sufficient depth for hippos to fully submerge and behave naturally. The nocturnal grazing behavior of hippos is often impossible to accommodate in managed collections, disrupting their natural activity rhythms.