Terms of endearment are not specifically northern, girls' names is far too simplistic, was looking for something more.

Pudding? Really? Not in my experience, and I grew up in the North. And cocker is never used alone.

Ah the vagaries of language, dialect and accents, To my ear [Yorkshire] "Pet" is more North East, Tyneside, Northumberland areas. Puddin' same area and Scottish but used more as a soft insult "ye daft puddin'. I have heard "Cocker" used on it's own as a greeting similar to "mucker" in the south Yorkshire, Derbyshire region., and I think "Duck" is quite widespread among older generations. On the other hand I could be completely wrong.

Duck is (or was, when I was growing up) most common in the Midlands, Leics, Derbyshire, Notts. I.e. not Northern. Same for some of the others, which are used to a varying degree in different parts of England.