wrote in a message:
Would a magpie attack a robin's nest?

Most certainly. Magpies *do* take eggs and young from nests, they like most
members of the Corvidae family are great predators. I have watched a family
of jackdaws systematically take all the young from a blackbird's nest and
have seen rooks taking the young from their neighbour's nests in a rookery.

Bill Brewer