Other than a bird, can you name an animal that sings?
How about a mouse?
A singing mouse might evoke memories of animated childhood films, but singing also occurs among real mice, producing complex songs to attract a mate. The songs are too high frequency for the human ear to detect, but when lowered by a few octaves, sound very similar to the tweeting of a bird. The sounds, far from being random, show variation and structure that qualify as rhythm. It’s not yet known whether the quality of the singing affects the chances of a male mouse attracting a female.