Beaver's "prefer" birch, poplar,willow, cotton wood and the like. I have seen them chew on other including hedge 'yuck' when times are tough. I don't think the cypress will be first on the list of groceries. I have never seem them chose to eat a cedar or pine when other trees are avalible, but I have seen them remove a cedar that was in the way though. We don't have a lot of Cypress where I trap so I don't "know for a fact" that they wouldn't chew on them.
RKR
P.S. like Mtn Bee said keep the cages on until the beaver are gone, if you don't have someone deal with they now you will wish you had next fall, and there will be more of them to remove.