Saw any perches on your bird feeders in half. This will give enough space for small birds to perch while preventing larger birds from landing.
Remove platform feeders and regularly clean birdseed from the ground. Replace the current feeders with a cage-type suet feeder to provide suet in the winter or a hopper feeder to provide loose seed during the warmer months. The cage around the suet feeder allows smaller birds to access the food inside while blocking larger birds. Hopper feeders are designed to close under the weight of larger birds or squirrels, blocking access to food.
Wrap chicken wire around your feeders if you prefer not to replace them entirely. The mesh will prevent larger birds from accessing the food inside.
Avoid birdseed mixes containing milo, sunflower seeds, millet or cracked corn, which blackbirds favor. Instead, try safflower seed or peanuts.