E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Magpie.
A contraction of magotpie, or magata-pie. Mag is generally thought to be a contraction of Margaret; thus we have Robin red-breast, Tom-tit, Philipi.e. a sparrow, etc.
1
Angurs and understood relations have
(By magotpies, and choughs, and rooks) brought forth