I confess I'm not really sure if they're ravens, carrion crow or rooks — I haven't got close enough to use my excellent RSPB bird books to distinguish them — but I do know that in a valley I regularly visit in the Morvan in Burgundy, there's lots of one or more crow species, and they seem to interact in interesting ways, forming, particularly in winter, quite large groups that swoop around at dusk, raucously dominating the neighbourhood.
So when I saw Mark Cocker's Crow Country, it was clearly a book that I'd not only read, but read in France. Which is what I've just done, and it's left me with a strong desire to learn more about my local corvids, because I'm sure there's a lot to be discovered.
The fact that Cocker describes himself as a "nature writer" did give me some pause — the more literary end of nature writing tends to leave me cold — but although some passages of Crow Country were a bit too far down the poetical side for my taste, overall I found it a fascinating account of the natural history of rooks and jackdaws in Britain, and gave me plenty of information about their French cousins.
The key line of the book is Cocker's attempt to understand rook behaviour, and particularly their spending part of winter in large, sometimes enormous, mass roosts. He starts with their rookeries (breeding centres), the reasons for which are well established.
"In the nesting season, the abundant supply of worms is the key to the rook's success. The onset of the breeding cycle in earliest spring is timed to coincide with the maximum availability of prey for the chicks. But the food items aren't spread evenly, they're clustered randomly...It's thought that rooks have evolved to share resources and capitalise on the shifting and temporary abundances by pursuing a feeding strategy of follow-my-leader.... Each bird discovering a food hotspot faces the disadvantage of competition from neighbours, but it is more than compensated by the opportunity, on all occasions when it is less successful, to share the good fortune uncovered by others."