To reduce visits by avian predators such as American Crows and Blue Jays, provide bird seed in tube feeders.  Because of their larger size, hopper feeders and platform feeders provide easier access for larger-bodied birds to perch than smaller ones.  One way to reduce the chance that birds of prey will successfully catch birds at your feeders is to place your bird feeders close to cover.  Previous research has found that birds are more abundant at bird feeders closer to vegetation such as a tree or shrub than farther away.  This may be so that birds can quickly find cover when a bird of prey visits the yard.  A tree or shrub with dense branches and leaves may offer greater protection, but make sure you select a plant that is native to your area.