crows

It's been damp and the cutting of the backfield was delayed, but the fine weather has arrived and silage making has started.

Swades of perennial rye grass, their silver backs turning in the breeze, go down under the moor.

Before it's even finished, the row, the rooks are in behind it, foraging worms and beetles turned over by the blades.

Squabbling over the best ground, a few birds lifting off and resettling close by, Jackdaws move in beside them, pale-eyed, watching everything.

The nearby farms keep a year-round buffet.

Silage pits, wrapped bales, feeding troughs, where the rooks and the jackdaws, the regulars, are joined by hooded crows and magpies.

At a distance on the Douglas Fir, a pair of ravens survey the whole field from above.

What we're watching here ecologists would say is the rise of the mesopredators.

Corvid numbers locally have climbed over the past couple of decades, partly because the eagles and large raptors that once kept them in check have themselves been pushed to the margins by persecution and habitat loss.

Into that gap the corvids have moved and they haven't done it with muscle.

They've done it with memory and problem solving.

The same two things that helped the raven scavenge the fox.

It's well documented elsewhere too.

In New Caledonia, crows shape hooked tools from twigs to get grubs out of bark.

In laboratory tests, they'll drop stones into a half-filled tube of water to float food up within reach.

the kind of problem-solving researchers have compared to a seven-year-old child's.

And it goes further than any one bird's cleverness.

Researchers tracking American crows found that birds will remember the face of a person who once trapped them and will teach that memory to their young.

Years on, crows that were never trapped themselves, born long after any trapping, were still mobbing the person responsible.

Memory handed down the generations.