Carrion Crows congregate in a 'murder'; Rooks breed in a rookery; and there's probably a collective noun for Jackdaws too. But what do you call a mixed gathering of Rooks and Jackdaws? After a recent experience at the now-famous Buckenham Carrs roost (a star attraction in 52 wildlife weekends, following its discovery by local nature writer Mark Cocker), I wonder whether it might be a 'chaos of corvids'. I haven't yet managed quite the images I am after. But I'm learning - and loving trying.