Is it illegal for a neighbor to have small spy cameras installed on their roof aimed towards my home?

We bought our new place in October & I just noticed the cameras now so I don't know if they were installed before we moved here or not.I don't have anything to hide but I do like my privacy & with the world today you just never know what kind of people you are dealing with..I have two toddler nieces that run around my yard & I do not want them filmed nor do I my privacy in my home to be compromised.