Country & Coast: Multiple factors behind sad decline of majestic kestrels

MOTORWAY travel used to mean indigestible food and high-priced fuel, but it at least promised one benefit beyond offering the quickest way of getting from A to B. I could always depend on seeing a kestrel hovering over the grass verges.
Kestrel numbers are in decline.  Pic: John Thompson.Kestrel numbers are in decline.  Pic: John Thompson.
Kestrel numbers are in decline. Pic: John Thompson.

At the weekend there was one of these small birds of prey in the corner of my right eye as I drove west on the M62 near Huddersfield, and it seemed to have come to a dead halt in the air as it scanned the undergrowth for food. It’s an offence to pull onto the hard shoulder of a motorway unless there’s a health or technical emergency, so I was unable to yield to the temptation of stopping to watch the bird with binoculars as it hunted for small rodents in the motorway’s steep verges.

Years ago, though, I would have taken a complacent attitude to seeing a kestrel. Along with the carrion crows and magpies that scavenge for roadkill, kestrels were a ubiquitous presence along motorways. They were the classic example of a bird adapting to the changing landscape by finding an easy food source in the mice, voles and shrews that colonised grassy motorway embankments. Back in the 1980s I recall counting more than 20 on a drive down the M1 from Leeds to Sheffield. Elsewhere the kestrel - once known as the stand hawk in the West Riding - was common enough for The Birds of Yorkshire author John Mather to describe it as “certainly the most familiar bird of prey in the Yorkshire countryside”. It was also at home in our cities, and I can remember a pair nesting on the roof of Leeds Corn Exchange in the 1970s and at Wakefield Prison a few years later.

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But over the past decade its numbers have declined quite dramatically. The British Trust for Ornithology first revealed the downturn in fortunes back in 2010 when a survey found that the UK kestrel population had gone down by more than 20 per cent since 1995. A reduction in numbers across farmland was blamed on intensive farming cutting the population of small mammals that account for most of its food, and chemical seed dressings impacting on the fertility of their eggs.

More recently the RSPB has set up a project to study the kestrel’s decline, and the early conclusions appear to confirm the use of agri-chemicals as well as increased deployment of rodenticides against rats. There also seems to be fewer nesting sites in trees and buildings available because of competition from better-fairing species like jackdaws and magpies. Another factor being investigated is climate change, particularly the effect of increased rainfall on the small mammals that make up the bulk of the kestrel’s diet.

Thankfully, in some areas like the upland fringes of the South Pennines the bird still appears to be thriving. And for the time being it is still possible to encounter kestrels hovering at the side of the M62 to the west of the M1.