Songbirds practice singing in their sleep.

Many musicians spend countless hours in rehearsal studios perfecting their tunes. But to some songbirds, rehearsing is also second nature; they’re even known to practice singing in their sleep. This behavior is similar to how a dog’s paws twitch while it snoozes, only in the case of songbirds, it’s the vocal muscles in the throat that experience subconscious movement.

Researchers confirmed this phenomenon by implanting electrodes in sleeping birds such as the zebra finch. While zebra finches are known to croon in a more methodical staccato style when awake, the birds were observed producing disjointed, sporadic notes as they slept, a behavior researchers likened to “learning a musical instrument.” Similar — albeit less common — behavior has also been viewed in great kiskadees, which produced louder and more aggressive tones in their sleep.