What's the meaning of a "Calling Bird" and does it actually matter?

When singing the Twelve Days of Christmas, most people do not think about the meaning of the words or the interpretation of the song. For example, people interpret a calling bird as a song bird. However, the original song referred to “Four Colly Birds”. The word colly means “black as coal or soot” so it is likely that the gift was four blackbirds (Turdus merula). History tell us that blackbirds were eaten in the past, as referred to in the children’s nursery rhyme “Four And Twenty Blackbirds Baked In A Pie”.