What spring bird persistently sings, day and night?
Your bird is most likely to be a northern mockingbird. Don’t worry, male mockingbirds only perform this nocturnal singing in the spring and summer during the time of the full moon. Try running an electric fan (to create a buffer of sound) and using your earplugs on those nights when the male mockingbird is singing. Having a mocker around is a good thing-you might even consider yourself lucky! An excellent source for backyard bird identification is An Identification Guide to Backyard Birds.