Kestrel
Falco tinnunculus
Our most familiar and common falcon, the Kestrel is famous as a ‘motorway hawk’, often seen hovering over roadside verges. It is the only commonly occurring falcon in Britain that habitually hovers, although Lesser Kestrel and Red-footed Falcon in Europe also use this hunting technique. Buzzard and Rough-legged Buzzard also habitually hover.
It was believed, and may be partially the case, that hovering birds were watching for movement - certainly regardless of how much the body moves the head remains remarkable still while the bird is concentrating on the ground - but it is now known that vole urine (which is constantly dribbled as the animal goes about its life) fluoresces and Kestrels are able to see the urine trails in the grass, leading them with a ‘road map’ to where the animal currently is.
Despite the classic hovering hunting method being so well-known, Kestrels prefer to employ the sit and wait approach to hunting, spending long periods sitting still on a post, tree or rock, watching until some item of prey is spotted, when the bird will slip off to pounce. In fact, hovering could be considered a sit and wait hunting technique where there is no suitable perch to use.
Our Kestrel, known elsewhere in its range as Common Kestrel, is one of a group of similar species many of which are extremely range-restricted island species.
VITAL STATISTICS
Size: Average 34 cm, wingspan 76cm. Females (220g) larger than males (190g).
Status. Resident breeder. Passage/winter visitor.
Population size. 45,000 pairs.
Conservation status: AMBER (Due to recent breeding population decline).
Lifespan: Average age in the wild is 4 years. Adults have a 69% year-to-year survival. First year survival is 32%. The oldest known wild bird was almost 16 years old (ringing recovery).
Nesting: Unusually among British birds of prey, Kestrel is a cavity nester, preferring holes in cliffs, trees or buildings. They can be found nesting inside industrial structures and readily take to nest boxes. Kestrels are remarkably tolerant of other near-by Kestrels and may nest semi-colonially in areas of high numbers. Only the female incubates the eggs, but both birds brood and provision the young.
Number of eggs: 4-5
Incubation: 28-29 days
Fledging time: 32-37 days
Habitat and Distribution: Kestrels are familiar and widespread, only absent from areas in the most extreme north and west of the country. Although birds of fairly open country, they adapt well to a range of habitats and can be found in urban areas, farmland and even large gardens as well as open heathland, moorland and upland areas.
Movements: Most British Kestrels are fairly sedentary, with some 75% not moving more than 70km from their natal area. As with most birds of prey, however, young birds may travel more widely before settling to breed. Kestrels can easily travel over open water, and regularly cross the North Sea. Many Scandinavian birds, escaping harsh winters, will winter in the UK.
Feeding: Kestrels feed almost exclusively on small mouse-sized mammals. Voles are a favourite, although in certain areas young Rats may be an important food source exposing Kestrels to commercial rodent poisons. Kestrels are, however, very adaptable birds and will make use of any opportunities as they arrive, including taking birds, especially nestlings, invertebrates, bats, reptiles and amphibians but they lack the agility to be especially good predators of birds, unlike the other falcons Merlin, Peregrine and Hobby. Each Kestrel requires the equivalent of 4-8 voles a day.