Can I over feed the outside birds?

I have a garden in my back yard. I read about the little ecosystem of a garden and how birds are a big part of keeping my plants healthy.

I’d say about a dozen birds have been frequenting my garden since I started feeding them seeds. At first I just fed them in the morning. Now I feed them in the evening, as well.

I want the birds to eat the bugs and other critters I do not want in my garden. Is it possible for me to feed them so much that they won’t eat anything else? Or do wild birds naturally regulate their food intake?