Cuckoos Can Mimic Other Eggs

Cuckoos can mimic other eggs, like lay them so that they match down to the shade of color. I imagine that this whole scheme only works if they can fool the host parents. How do they know? That's a question that we don't necessarily have a fulln answer to,. But what we do know is that, yes, they will make sort of pre drop off flights where they observe on the positionality of the nest. They're going to parasitize.