Grackles are large birds with even larger appetites. They eat your bird seed and scare away smaller birds. Grackles often raid backyards during their migrant seasons in spring and fall, and they also are found in areas where they spend the winter. To get rid of grackles, you have to make your backyard less appealing to them so they don't return. You need a tube feeder or a finch feeder, a broom, small cages for covering objects, and safflower seed.
Replace platform feeders with tube feeders or finch feeders
Install a tube feeder or finch feeder in your backyard. The tube feeder has nowhere for grackles to land, so they can't eat your bird seed. The finch feeder is designed for small birds with narrow bills, so grackles can't access your bird seed with their large bills.
Clean any bird seed off of surfaces
Loose bird seed attracts grackles, so clean it off any open surfaces.
Install cages over anything grackles will eat
Cages with small holes block grackles from reaching anything you don't want them to.
Put out safflower seed
Instead of average bird seed, put out safflower seed for wild birds. Most birds like safflower seed, but grackles don't.