Years ago, we had a rosebush in the back yard. I noticed that a robin had built her nest on the top of it, she had 3 eggs waiting to be hatched. I thought it was a great defensive move, the bush was full of thorns and I dont think a snake would try to climb it to get to the eggs. The following spring, not sure if it was the same robin or a different one, but there was another nest in it, with eggs.