The Long Memory of Ducks

I just moved to the Olympic Peninsula in Washington State. My property sports a wet-weather pond, which the previous owner told me attracts ducks each spring. The neighbors filled in the story, which astonished me. The previous owners began living here 22 years ago. Before that, a family lived on the property, which encompassed most of the neighbor's lots back then. This family planted trees and beautiful gardens, and raised ducks. Apparently, some of the ducks went feral, but they or their offspring return every year to brood and splash in the pond until it dries up. Then they leave. The cycle has been repeating for well over 22 years.