This verse is often sung as 4 calling birds, but is is actually 4 colly or collier, which is a black bird. In England a coal mine is called a colliery which means black like coal. This gift sets your true love back $599.96. I am sure that doesn't include the cage, bird seed, etc etc etc. And do you want birds to take care of, which is why I have posted this version of Beatles-Black Birds (Acoustic Cover-Tomothy Moloi).
Both of you will fly.