Kestrel

There have been several reports this week of kestrels hunting over Kestrel Field.

The kestrel (Falco tinnunculus) is a field vole specialist: they make up the majority of its diet and the reserve has well-stocked field vole colonies in most, if not all, of its fields.

You may have seen our kestrels hovering, flying into the wind and using tail and wings to hold position, all the while keeping the head absolutely still with eyes fixed on the ground. Prey spotted, a kestrel drops suddenly.

A female kestrel hovering

Kestrels’ eyesight is remarkable. They can see ultraviolet light, which means that they see the urine that field voles use to scent-mark their trails around the colony; they can they spot the movements of the smallest vole from 50 metres up and judge exactly how far away it is, its size, shape and position.

A kestrel will catch several voles in succession and cache some for later. This store is usually eaten the same day, just before dusk, to ensure that the bird goes to roost on a full stomach.

A male kestrel is smaller than the female and has a blue grey head.

Kestrel numbers fluctuate with field vole numbers but, in general, have declined since the 1970s because modern farming methods have slowly reduced field vole habitat. Higher densities of grazing animals, close-cut grass crops, successions of arable crops and the use of pesticides have all played their part.

The kestrel population was estimated at 52,000 breeding pairs for the 1988-91 Breeding Bird Atlas but is believed to have fallen by almost 30% in the last 25 years. Their present UK Conservation Status is amber.

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