Uccello was kind of a superman. Artist, mostly frescoes. Early adopter of linear perspective. I was surprised by the cloister at Sta. Maria Novella in Florence, which was undergoing restoration two years ago.
Since the words are the same to say "it is a bird" and "is it a bird", what is happening with vocal tone/variation to show that it's a question? Do Italians lilt up in pitch, like American English speakers?
Nor does it have to be :P "Esso" is the word for "it", but it's disused in modern Italian, it survives in very formal contexts and some literature. You probably used "lui" (he) and duolingo corrected you, but you should always omit "it" when translating.