Last year a robin nested outside my window on the downspout coming from the roof. Ended up being a pretty bad place for a nest, the eggs were snatched by a crow! I saw it happen while I was mowing the lawn. In 5 seconds all that work making a nest was for nothing! Nature.
Wow! That must have been crazy to witness! Crows, like most creatures, are opportunists. I wonder if it needed that protein in its diet or it was for a different reason. I'm sure the robins made a new nest shortly after somewhere else.