One of the most effective ways to keep ants out of hummingbird feeders is to buy and use an ant moat. Additionally, making sure to clean up any spilled nectar below a feeder and moving discovered feeders several feet (to a new branch or tree) is an easy first step that can work. Additionally, some hummingbird feeders include built in ant moats, such as Pennington 32 oz. Decorative Hummingbird Feeder.