I discovered these worms or caterpillars on the evergreen bush in my yard. They're really creeeeeeeepy, because when you move your hand toward them, they all wave in unison. I've put in a link to a video showing their waving behavior. Also photos of what they look like on the evergreen, one of the caterpillars close up, and another to show what they're doing to this poor evergreen bush.

I need to know what they are, and how to stop them from killing my bush without using poison, as this bush is in my bird-feeding area and I don't want to poison the birds.

Here's a link to the video: Wiggle-worms