Washington was a lover of exotic animals, as well as gardening. He maintained extensive menageries on his country properties, first at Bellport, and later at Mendham. On Long Island, it is reported that he was often seen with a bird or monkey on his shoulder. At both his menageries, Washington specialized in rare birds, but such animals as deer, sheep, goats, and antelope are also recorded at Bellport, and deer, llamas, and zebras are recorded among the hundreds of animals in the larger space at Mendham. Socially, he was an active member of the Lotos Club, a literary gentlemen's club in New York City.