I See Bluebirds Here Occasionally, and they Look Like Sparkling Blue Jewels when the Sun Shines on their Feathers. A Mystery Bird Around Here has been Singing, "Sweet! Sweet! Sweet!" and I've Yet to See him or Identify him. (That Song he Sings is Probably about himself, Lol!)
Yup, it's most likely a 'he', then.
Those huge bird voices come from birds so tiny they're barely the size of an olive on a toothpick. Makes the voice owner harder to find.
Click the pic: