The ornate Owls Club building at 378 N. Main Ave. lies amid other stately old homes and offices in the historic El Presidio neighborhood, where it was built to house a club of bachelors who called themselves owls because they wanted to “nest” while waiting to find brides. The Tucson-based Center for Biological Diversity plans to move into the 112-year-old Owls Club mansion downtown in June, after buying it for $1.3 million.