Yes, bird poop does stain pavers if it is left on the surface for an extended amount of time. The longer the poop sits on the pavers, the harder it will be to remove. Try using a pressure washer with a nozzle set to 18 inches from the surface. Start at one end and work your way across the paver. Be careful not to damage the surface of the pavers with too much pressure. Make sure to wear safety goggles and gloves when using a pressure washer.