Today is the Fourth Day of Christmas. In this verse, The "four calling birds" refers to the four evangelists who wrote the Gospels—Matthew, Mark, Luke and John—which sing the song of salvation through Jesus Christ.
On the fourth day of Christmas,
my true love sent to me
Four calling birds,
Three French hens,
Two turtle doves,
And a partridge in a pear tree.
This post is one of a series explaining the Twelve Days of Christmas. Over the next 9 days of the Christmas season (ending on January 6th "The Epiphany") I'll post more information about the following verses of this song. I hope you'll find the "coded" meanings as interesting as I have! For more information, you can also check out appleseeds.org and CIN. Picture from AtHomeWithGod.com