The Great Outdoors: As kestrel and peregrine eye territory, a new threat casts a dark shadow

Earliest March. The snow fell in frail fragments of showers that brought to mind the blown seed of rosebay willowherb.

I had gone to see how far advanced the nesting preparations of the falcon tribes might be, or if they had even begun. The big trees along the base of the hill offered cover. My destination was a point where I could see the peregrine crag, a gully – the ravens’ home – and a certain whin-shrouded rock above a hefty buttress where kestrels nest, half a mile of hillside.

Settle and still.

Take the temperature of the hour. Scan the lie of the land.

This is the best part of the job, re-examining that which is familiar, knowing what to expect, having expectations confirmed – or confounded by something utterly new. A male kestrel, compact and sleek, stepped up from scree-rooted ash, side-slipped parallel to the face of the hill, leading with the open primary feathers of its left wing, then eased to a hovering standstill above a small clearing of steep grassy hillside in a jungle of whin bushes, also known as gorse.

Black-tipped wings high, tail fanned wide and almost vertically below his head, a glowing triangle of pale and dark tawny, grey skullcap, black edging to pale silvery-grey tail, he was magnificent in the sunlight.

His falcon eyes can differentiate, from 50 feet above, between a blade of grass moving in the wind and the whiskers of a crouching vole a-twitch with fear. Does he only have eyes for voles, mice, shrews, small packages of food wrapped in fur? Or – if necessary – beetles, insects, worms? His birding options – skylark, meadow pipit, for example – are elsewhere, on the hill’s grassier northern flank.

But might he read the land too? Might he ponder its changing face?

Every spring the whins advance, and consume more open ground. Less room for voles and mice and worms, less hunting terrain for the kestrel tribe; arguably more nesting cover for small birds, but that suits the peregrine and sparrowhawk better than the kestrel, for the kestrel is a mouser by instinct, a birder by necessity, so every spring this hillside becomes a little less kestrel-friendly.

From where I sit looking up at the kestrel looking down, the bird’s dilemma as I see it is this. The kestrels have a good nest site on a flat rock atop a small rockface, mostly hidden by – inevitably – a whin bush. It has served them well. But how much longer before the rockface is engulfed?

So do the birds stay put and, if so, must they change their instinctive behaviour to accommodate the changed circumstances? Must they become birders for a living, become more efficient at catching prey in the air?

Or, must they accept their preferences mean hunting further from the nest and having to carry prey further back to the nest, which might mean in turn they become more vulnerable to some of their neighbours – peregrines, ravens and buzzards?

Or do the kestrels pull out? Do they abandon the safe nest to take their chances beyond the whins, or on the far side of the hill where there is plenty of open grassland but where nest sites could be a problem for there are no crags and precious few trees? And will they reason all that out and make a decision, or will instinct simply kick in and evict them?

With my questions still poised – kestrel-like – on the hill air, the hovering bird fell 30 feet to a few inches above the whins and sped in level flight towards the blunt bulk of the buttress, a manoeuvre that had the air of drastic evasion. The source of its discomfort was not hard to pin down. Peregrines.

The courtship flight of a pair of peregrine falcons is a berserk chase through the heart of the home territory, as remarkable for its control and precision as for its speed. Its objective may be nothing more than pair-bonding, but, when it free-falls from several hundred feet above the summit, then crackles along the face of the crag in a blur, many a small furred or feathered heart must skip a beat.

One of those flimsy snow showers lent a further frisson of subtle beauty to the spectacle, the whole event was simply a thing of wonder to my eyes.

As far as I know, the kestrel is unimpressed with the concept of a silkscreen of falling snow and, given it knows it can hold its own in the peregrine’s company more often than not, it neither froze nor dived for cover but rather flew in the opposite direction on a lower contour, perched in another ash below the buttress.

The choice of the perch was interesting. It was in the topmost branches, so not taking cover, not deferring, but it offered an unobstructed view of the entire crag. An object lesson slipped into place: sometimes the sheer spectacle of a predatory presence is a weapon in itself.

The kestrel will be well enough versed in the wiles of the peregrine to know that when it hunts it hunts alone, and when the pair fly in tandem in the run-up to nesting time it is typical nesting behaviour . Yet it opted for a better vantage point.

So it would have a keen eye for what the peregrines did next, for they segued into a long, oval-shaped circuit across the hillside at the base of the crags, a circuit that passed a few feet above the kestrels’ hidden nest ledge.

As the peregrines completed their circuit, they split apart: the female rose to perch near the eyrie ledge, the male drifted slowly up at an angle and back across the face of the crag to a perch in the gully, no more than four yards from the scruffy mound of the ravens’ nest.

It had buzzed the kestrel rock and door-stepped the sitting ravens in the same manoeuvre – so was it a point being made about dominance of the airspace while the neighbourhood buzzards’ backs were turned?

The thought remained incomplete. I still had my glasses on the perched peregrine in the gully when it took off in a manner that suggested urgency, pursuing a steep climb up the cramped confines of the gully’s airspace, until it cleared the hillside and emerged against the sky.

There it began circling slowly, crying out a shrill and repetitive three-syllable note with more than a hint of alarm to it. A second bird crept into the glasses much higher than the peregrine.

There followed a few seconds of confusion while I rationalised scale and distance and decided I was looking at something much larger and much further away. Then it banked, unfurled a vast acreage of wingspan and its tail blazed vivid white in a blink of sunlight, and these are the unmistakable emblems of a sea eagle.

Snow still fell on an icy east wind, but the eagle descended from a clear blue northern sky towards the south, towards the peregrine, towards me.

I thought aloud: “This should be good.”

Kestrels are Britain’s most widely distributed bird of prey, breeding throughout the mainland and islands.

The name “peregrine” means wanderer or pilgrim due to their solitary nature and how far they travel for food.

In medieval falconry the kestrel had a lowly status and was reserved for the knave or servants of the house.