Experimental feeders at a field site in Winters, Calif. The researchers assigned hummingbird feeders to one of three treatments: (1) access by both hummingbirds and insects (open feeders), (2) restricted access by birds but access by insects allowed (caged feeders, 1.5 cm square mesh), or (3) restricted access by both birds and insects (feeders bagged using gallon paint strainer bags), with two replicates of each treatment set up at each site. (Photo by Casie Lee)