Department of Natural Resources officials released the white swans as part of a restoration project that places birds to nest and produce offspring that are then released into the wild.
Trumpeter swans are America's largest waterfowl, weighing up to 35 pounds with an 8-foot wingspan. They are Iowa's only native nesting swan.
Once common across much of the continent, they were hunted for their feathers to near extinction by the late 1800s. The swans now have protected status, and their population has grown with help from nesting projects.
The Great Ape Trust's grounds include 40 acres of lakes and wetlands, making it a perfect spot for the swans. And the birds will give the bonobos at the trust an interesting distraction.
"They're going to be curious about what's going on down here," Swartz said. "They monitor their environment closely."