I have been trying to catch the raccoons in the act of raiding the bird feeder, and I finally saw it tonight, with the help of Walter's sharp ears. His cries alerted me to the raccoons right outside the kitchen window.
I saw one of the raccoons jump up onto the window ledge, and from there, he made a flying leap onto the bird feeder above him. The tray of the bird feeder went straight up in the air because of the raccoon hanging on one side of it. I saw the bird seed spill onto the ground. The raccoon held onto the bird feeder tray with the grasping paws of his legs, and then he jumped onto the ground.
I saw him do this twice. Now I just need to get the proper equipment to take a video of it so you'll believe me!