From hippos to rhinos
To keep the animals healthy, hippo keepers dump and refill the hippo pool several times a week. That means pouring millions of gallons of water down the drain every year. The zoo wanted to do better than that. So, when the zoo reached out to voters in 2008, it asked for funds to improve the hippo exhibit, primarily the installation of a water-saving filtration system.
As part of the master planning process, the zoo analyzed energy use across the entire zoo campus and found that pumps and filtration systems use the most power by far. This meant the zoo was about to install a water-saving hippo pool filtration system that would use a lot of energy. That didn't make economic sense or meet zoo and Metro sustainability goals.
That's when keepers, managers and habitat designers started talking about rhinos. Black rhinos are critically endangered in the wild. In their native habitat in southern and eastern Africa, a historic population of 500,000 rhinos was reduced to 70,000 by the 1970s. With an increase in poaching, their numbers crashed, hitting a low of 2,300 in the 1990s. Thanks to successful conservation and anti-poaching efforts, black rhino numbers have gradually increased to around 5,000 currently.
Unlike hippos, rhinos don't require pools so pose no issues regarding water use or filtration. In addition, rhinos are better suited to the zoo's long-term species plan. The zoo's 20-year master plan calls for construction of an Africa savanna habitat shared by a number of large grassland species. Rhinos can share habitat with gazelles and giraffes while hippos are more aggressive and cannot share habitat. For all these reasons, the zoo now plans to focus on rhinos.
The Oregon Zoo acquired a male black rhino named Ruka in 2015. It is hoped that he and the zoo's female rhino, Zuri, will be compatible and add to the population of these critically endangered animals. Design of the new habitat will support breeding and calf rearing.
When the zoo is ready to start construction on this project, the zoo's hippos will head to a new home in another zoo. Their pool will be decommissioned and their space opened up for rhino use. The expanded rhino habitat will eventually become part of a much larger multi-species savanna habitat.