Pretty positive it's just squirrels.
It's very routine to have them on roofs on my neighborhood (roofs all similar to yours) during any season of the year. They seem to simply like to occasionally go uop there as a vantage point.
But make sure that's all
they are doing up there -- check to ensure they aren't crawling into the walls/roof via some gap or hole somewhere. They're like mice - they can fit through some freaky small holes & gaps, so look close