Here's what you'll have a chance to find inside:
Green-Winged Teal Duck
Welsh Harlequin Duck
Again, a single box costs 20 Farm Cash, which is more than the typical price for a single Duck in the store (normally 16 Farm Cash or less), but I suppose you're paying extra for the mystery. I'm not sure if that should be the other way around (where you'd pay more for a guarantee at what you're getting), but I suppose I'll let that one slide. If you want to take a chance on receiving your favorite of this lineup, make sure you do so before tomorrow night, or you'll lose your chance!
Will you purchase the Duck-filled Birthday Mystery Box in FarmVille? If further boxes are released, which animals would you like to see represented inside? Let us know in the comments.