I grow a lot of NW native plants that are good food sources for birds. A few years ago, I started some Indian plum (Oemleria cerasiformis) from seed. They made a lot of fruit last year, which the birds cleaned off before they were even ripe. This year, hundreds of seedlings are popping up all over my garden beds, near and far from the mature plants. And they grow very fast. Bark mulch doesn't stop them from germinating.

I don't want to deprive the birds of this wonderful food source, but I will never be able to keep up with all these seedlings. I am considering killing the mature plants. Can anybody think of a better solution?