Do Crows do that?

We've had an abundance of crows in the area this spring. We've also found an abundance of birds nests on the ground. Some of them we attributed to high winds... nests that were small or not complete. But then we were also finding bigger nests on the ground. Nests with mud construction. Nests that had been wrapped around branches in the tree. I'm starting to wonder if the two events might be related... (the multitude of crows and many bird nests on the ground)... do crows knock nests out of trees? Do they go after youngsters in the nest?