Thanks for the link, DtG: jackdaws they is, or near offer [OI!!! -- ed]. Case tentatively closed.

.... which led me onto pictures of Magpies ("Oh, we know what those are," says Herself), which reminded me of hearing a poem about them on the wireless, of which all I can remember is:

They are crows who have won the pools
and strut around all day in their dinnerjackets