They look like boys to me. Also it's not just that the wood isn't the right type it can KILL your chinchillas. The plywood is dangerous to chinchillas, it's the same story as I've read with people using plastic, shelves, hidey houses, ect and saying "oh but they never chew on it", the chins may not chew on it yet (and may not for years if ever), but then one day they just decide for who knows what reason to chew the heck out of it. Do you know what kind of glue was used to make the plywood? most industrial glues are toxic, and do you know what kind of wood was used? The beech I'm not sure about, I've seen it on both safe and unsafe lists, I know for a fact that parts of the tree are poisonous but don't know about the wood.