Hovering wonder

Kestrel hovering

It is crisp and sunny, cold and windy. Cycling up the lane to Borley I stop just downhill of my favourite oak tree where I sometimes see a kestrel sitting on a branch.
He is here today, surveying the scene. Something in the field edges below piques his interest and the bird drops from its perch. It is definitely a male kestrel, with a rust-coloured back and thick black bar across the base of its grey tail feathers. Facing into the wind, he flutters his wings furiously to stay in position, the broad tail acting as a rudder, head perfectly still and focussed downwards. Is it possible to ‘tread air’? If it is, then the kestrel has it down to an art.

Out on my travels over the past couple of weeks, I’ve seen birds of prey aplenty. A muscular buzzard standing in a field near Bury; a kite tacking low and slow over a road at Hadleigh. But, last week, on a morning drive to Ipswich I saw three kestrels at different points on the journey, each one in the classic cruciform hovering position above a roadside verge.
And each time, I couldn’t help but slow down the car and crane my neck over the steering wheel to get a better view of this iconic sight of the British wildlife landscape. No wonder an old country term for a kestrel is ‘windhover’. It is the most distinctive of poses – and one that fills me with wonder every time.
It is a sight that down has exercised poets. Ted Hughes described a hovering kestrel as holding ‘all creation in a weightless quiet / Steady as a hallucination in the streaming air’.
Gerald Manley Hopkins was moved to write about the ‘dapple-dawn-drawn Falcon, in his riding/Of the rolling level underneath him steady air, and striding/ High there, how he rung upon the rein of a wimpling wing.’

Kestrel for a Knave
But, despite its aerial acrobatics, the kestrel is often overlooked in conversations about birds of prey. Maybe it is disregarded because of its small size or for the fact that it is relatively commonplace compared with many other raptors. And it would seem, down the ages, the kestrel has never been that highly regarded. A hint to the species’ place in the pecking order is given in the preface to Barry Hines’ novel A Kestrel for a Knave, which was adapted for the classic 1969 film Kes. Hines quotes a medieval manuscript, which lists the birds suitable for different grades of aristocratic hunter:
“An Eagle for an Emperor, a Gyrfalcon for a King; a Peregrine for a Prince, a Saker for a Knight, a Merlin for a Lady; a Goshawk for a Yeoman, a Sparrowhawk for a Priest, a Musket for a Holy water Clerk, a Kestrel for a Knave.”

On the verge
But for me, it is exactly because the kestrel is seen so often that makes it special. There’s something reassuring about its appearance, like the rising song of the skylark or the haunting melody of the blackbird.
But what is it about roadside verges that attracts kestrels? It is almost as if they enjoy showing off their aerial skills to passing motorists – a busy road guaranteeing an audience.
A more sensible answer is verges are often the only wild spaces left in our country – a remnant of old meadowland between farmers’ fields and roads. They act as valuable wildlife corridors for all sorts of creatures including voles, the kestrel’s main source of food.
Another theory I’ve heard to explain the kestrel’s roadside fixation is that the constant rumble of traffic resembles the sound of rain to underground earthworms, who are enticed to the surface of verges and in the process provide a snack for the kestrels waiting above.

But to hunt from high above, good eyesight is a necessity, and the kestrel is said to have incredible vision – up to eight times better than humans, according to some scientists. It’s hard for us to conceive visual perception of such a magnitude, but imagine being able to pick out individual blades of grass from 20-30 metres up in the air.
And that’s not where the kestrel’s hunting prowess stops. Kestrels are also able to see UV light, which helps them track down voles and other small rodents, who lay scent trails of urine, which reflect ultraviolet (UV) light.
Experiments with captive kestrels have shown that kestrels flying over an area use vole scent marks to assess vole numbers. This enables kestrels to ‘screen’ large areas in a relatively short time and evaluate their suitability for hunting.
Perhaps not good news for voles; but another curiosity to ponder when you next see a kestrel hovering above.

Ross Bentley, Trustee of the Sudbury Common Lands Charity

Kestrel hovering - excellent eyesight