COASTAL KESTRELS
Hanging in the breeze, hunting for prey, this acrobatic raptor thrives beside the sea. Britain’s coastal paths are among the best places to witness the airborne antics of the beautiful ‘windhover’, says Mark Hillsdon
The beautiful ‘windhover’ is often sighted hanging motionless in the breeze along our coast. Find out more about this beguiling bird of prey with Mark Hillsdon.
Ihad been watching the kestrel for about 10 minutes as it hung on the wind, wings outstretched, the slightest movement of its fanned tail helping to stabilise it against the buffeting breeze. Its head remained stock-still as its eyes scanned the tussocky clifftop for the slightest sign of life. When it finally struck, it was fast and clean, a blur of chestnut and grey dropping from the sky to grab its unsuspecting prey.
For readers of a certain age, the kestrel will always hold a special place in our hearts. This elegant falcon was the symbol of the Young Ornithologists Club – a 1970s precursor to the RSPB’s current Wildlife Explorers – and our gateway to birdwatching. It offered excitement and intrigue, and was a bird that we often spotted hovering above motorway verges, our first visceral experience of a wild animal hunting.
Dr Matt Stevens, a conservation biologist at the Hawk Conservancy Trust (HCT), is one of those who was hooked at an early age. “It’s just such a great bird... it’s so enigmatic,” he says. “It’s full of attitude; it’s not just pretty, it’s got a bit of personality to it, too.”
The kestrel isn’t fussy about where it lives. It can be spotted in local parks, on the moors and hawking the edge of farmland. But one of the most dramatic places to see it is along the coast, from the saltmarshes of Pagham Harbour in West Sussex, to the sand dunes of
Formby Point in Lancashire and the beaches of Fife. On the coast, the kestrel can harness the breeze, says Matt, using it to hover over a perfect habitat of rough grassland that hides a smorgasbord of small mammals.
Craggy cliffs also offer perfect nesting sites, while the milder seaside climate is good for invertebrates, from earthworms to beetles, which kestrels will happily prey on, especially during the winter.
If there is a downside to the kestrel’s seaside idyll, it is the saltwater wetness, as kestrels, like most birds, have trouble metabolising salt. Attacks from gulls and corvids are also hard to avoid, and while kestrels will typically patrol a territory of between four to eight square kilometres, they will actively stay out of the way of another seaside falcon: the much larger peregrine.
FIELD VOLE FEAST
The vast proportion of a kestrel’s diet is made up of field voles, typically two or three a day, although in the breeding season the male will stockpile food, hiding it in a tree trunk or cavity before making deliveries back to the nest.
They will also take wood mice and, if they need to, switch to small birds such as meadow pipits and yellowhammers. Matt has found the remains of much bigger birds in kestrel nests, such as moorhen chicks and collared doves, alongside the bones of frogs. There are even records of these falcons taking fish, he says, plucking them from the water osprey-like.
As with so many birds of prey, kestrels have been persecuted over the years, especially when landowners realised they had a taste for pheasant chicks. Over one 30-year period in the late 1800s, explains Matt, one north Wales estate slaughtered 1,988 kestrels, drastically reducing the local population. However, a few years later, he says: “There was a vole plague in the borders of Scotland; they devastated an entire area, and all the landowners started to realise that having something that could eat voles was a good idea, so they were quite a bit more accommodating to kestrels after that.”
A kestrel’s most distinctive characteristic is its ability to hover,
which has earned it a wealth of nicknames, from wind-cuffer in the Orkneys, to windsucker in Kent. But while the sight of a kestrel hanging on the breeze can lift the spirits, this manner of flight takes a lot of energy, which is why they have developed other hunting techniques.
“I’ve seen them sat on a farmyard fence post and flying up to catch moths and invertebrates around a lamp,” says Matt. “With moths, they almost turn upside down; it’s incredible to watch.” They’re also masters of the ambush, he adds, and at dusk will sit patiently waiting for house sparrows to start to roost, before rising up and striking.
As well as their rare ability to hover – buzzards can manage it too, although without a kestrel’s grace – they have exceptional eyesight. While the human eye has around 38,000 photo receptors per millimetre, a kestrel has twice as many. As a result, says Matt, “a kestrel at the top of an 18m-tall tree would be able to see clearly a 2mm-long invertebrate on the ground.”
However, he continues, researchers have also shown that the kestrel’s ability to hunt using the UV spectrum is up for debate. It had been thought that a kestrel used UV light to spot vole urine in the undergrowth, a tell-tale sign of prey running around. But this theory has since been challenged, with scientists suggesting there is little difference between urine and water when it lands on grass or gravel.
LONG-TERM RELATIONSHIPS
Kestrels are largely monogamous. While a pair will separate over winter, they will come back together at the turn of the year when the male shows the female around potential sites, often in an area where they have nested before. The female starts laying around the end of April, and begins incubating once there are three eggs in the clutch, often going on to lay up to three more. The eggs hatch after a month, with the young kestrels fledging after five weeks. But it’s far from a top avian predator that emerges.
“When they fledge they’re quite cumbersome and clumsy,” says Matt. “The parents aren’t very patient and it’s a case of ‘get up and get on with it’,” with the young kestrels soon clambering around trees and the first fluttering flights accompanied by a slightly frantic ‘klee-klee-klee’. “For the first winter, you’ll often see them on fences and posts hunting for insects and exploiting those things that are a lot easier to catch.” But despite a somewhat laissez-faire attitude, the parents are protective for the first few weeks. “They’ll try and see everything off; they’re quite brave and they’ll have a go at most things, even buzzards.”
Matt’s work at the HCT involves four cavity-nesting raptors – barn, tawny and little owls – and his real passion, kestrels. “They’re a joy to watch. They’re always on the go, they’re just wonderful birds.”
He has spent the past five years assessing the role that nest boxes can play in kestrel conservation. Around 250 have been put up in central and southern England and although over 50% have been used, there hasn’t been a distinct increase in kestrel numbers.
However, the work has fed into a larger project examining what makes the best habitat for kestrels and the trust is encouraging farmers to adopt more of a landscape approach, such as areas planted with more pollen and nectar mixes, or strips of land left unmanaged for wildlife.
“If it’s good for kestrels, it’s going to be good for barn owls, invertebrates and small mammals,” explains Matt. “It’s about improving the environment in many different ways.”