Build your own using chicken wire or buy one of the commercial bird feeders made especially to solve this problem. Keep bird seed off the ground and stop filling your platform feeder for a week. Blackbirds and Starlings may get discoraged and move on. Shorten the perches on your tube feeders. If Starlings are eating all your suet, try a feeder that required the birds to hang upside down.
Woodpeckers can eat like that, but Starlings hate it.
Never buy seed mixes containing milo. Blackbirds also like millet and cracked corn, but few of the colorful songbirds eat these seeds. You might try offering safflower seeds instead of sunflower seeds in your tube feeders. Learn to appreciate Blackbirds. With this Duncraft feeder you can offer as many as three kinds of seed and lots of it.