Kestrel

The hovering falcon

The kestrel is the only falcon in most of its range that regularly hovers in place — hanging stationary in the air with rapidly beating wings and fanned tail while scanning the ground below. The hover is maintained against the wind, which provides lift; the bird adjusts continuously with fine movements of wingtip and tail feathers.

This hovering is metabolically expensive — it’s used when prey is visible and imminent, not as a general observation strategy.

UV vision for hunting voles

Kestrels can see into the ultraviolet spectrum (humans cannot). Voles — a staple prey — mark their runways and burrow entrances with urine, which reflects UV strongly. From above, a kestrel can literally see the vole’s trail network on the ground below, identifying high-traffic areas and targeting its hover accordingly.

This UV vision capability was discovered in the 1990s and helps explain the kestrel’s extraordinary hunting success in habitats where the prey is invisible to human-vision hunters.

A species in decline

Kestrel populations across much of Western Europe have declined significantly since the 1970s. The causes are multiple: agricultural intensification has reduced rough grassland margins (prime hunting habitat); rodenticide use reduces prey abundance; increased road traffic kills birds hunting road verges. In the UK, kestrel numbers have dropped by over 50% since 1970.

Males and females

The kestrel is strongly sexually dimorphic in coloration:

• Male — blue-grey head, chestnut back with black spots, grey tail with black terminal band
• Female — all-brown with heavy dark barring on back, brown streaked tail

The male’s blue-grey head against the chestnut body is one of the most distinctive small-bird color patterns in European birds.