|Simple but nice|
Houses of birds for bird actual use are usually wooden, other stuff works too, the holes have a diameter that will be specific for a species (maybe more than one). A house for a bluebird is about two inches, but other birds like small holes - you just have to look it up, or already know. Houses for purple martins are built in groups (kind of condos) because they're very social, some are very large.
|Some may like a rustic home|
|A single home (holes too big)|
|Purple Martins might like a "Victorian" home.|