Common Kestrel (Falco tinnunculus)

Male Kestrel - Eddie Raptor Foundation

The name Kestrel derives from the French "crécelle", meaning "to rattle", a reference to the bird's call (the French name is "crécerelle"). Similarly, tinnunculus in its Latin name means "little bell ringer", another reference to its call.

In terms of distribution the Kestrel is one of the most successful falcons, there being a variety of Kestrel present throughout all parts the world, with the exception of Antarctica & the tundra & deserts. The Common Kestrel (referred to as Kestrel, throughout the rest of the page) is the only species resident in the UK, it is found throughout Europe, Asia & Africa.

In the UK the kestrel population is suffering badly, the Breeding Bird Survey (BBS) records a 20% drop in the kestrel population between 1995 and 2008, and a further fall of 36% between 2008 and 2009.

The Kestrel is a true falcon, but it is unusual in its flying style & prey. Like most birds of prey, its preferred method of finding prey is still-hunting, when hunting in flight it is unique in being the only bird of prey to be able to hover. Kestrels "hover" facing into the wind, so they are moving through the air, but staying stationary with respect to the ground, this is called "wind-hovering". The oncoming wind gives sufficient lift to remain stationary with respect to the ground, the tail is spread, supplementing the air-catching effect of the wings, the alulas (feathers at the front bend of the wing) are raised & wingtip feathers separated to reduce turbulence which would cause stalling at such effectively low speeds. They are also able to dip their head downwards, much further than other falcons, enabling them to spot their prey from a much more upright position when hovering. They have evolved such that they can keep their head still, while flapping their wings fast, high-speed video photography has shown that the head will move as little as 1/4" during wind-hovering. Hovering in such a manner uses a lot of energy, but studies have shown that they catch around 10-15 times as much food as when searching in flight or still-hunting. Under strong wind conditions, Kestrels can also stay poised in the air, with their wings wide open & still, referred to as "kiting".

The male Kestrel is distinguished from the female, by the grey colouration of the head. Though some older females may show similar colouring to the male.

Kestrels are reasonably monogamous, staying in a pair for a long time, if not for life. Kestrels do not make their own nests, but will use old nests of other birds or nest in holes in trees, cliff ledges or even man-made structures, such as motorway bridges. 3-5 eggs are laid around late April to May, with about two days between each egg, incubation is normally done only by the female. Incubation is started when several eggs have been laid, but often before the complete clutch, resulting in the eggs hatching in a shorter period than they were laid. Incubation takes around 26-34 days. Once hatched, the chicks grow at a very fast rate, this means that much of the energy from the food they get is concentrated on growth, leaving them very vulnerable to the cold. Food is fetched by the male & sometimes brought directly to the nest, but often left close by, the male then calls to the female to get her to collect the food. The young require around the same amount of food as an adult to grow, so the male Kestrel can need to be collecting up to 7 times its normal catch of food, if all five chicks survive. The young are fully fledged in 4-5 weeks after hatching, but need to stay with the parents & be fed for up to 4 more weeks, before they have all their hunting skills, including the ability to hover.

The Kestrel's main prey is the field vole, though it will take small birds & invertebrates. Kestrels are able to see well into the ultra-violet spectrum. This enables them to track voles through grass very easily, as voles mark their trail with urine, which reflects ultra-violet light, sending out a big beacon to the Kestrels. At the end of the trail, there is either the vole itself, or its nest. It is very adaptable, adapting to different conditions, such as motorway verges & different food sources, when the normal food source of voles declines. A Kestrel needs to eat around 1/5th its own bodyweight in food per day, amounting to something like 2 voles.

Like many of birds of prey, the Kestrel was virtually eliminated in parts of Britain, particularly by gamekeepers during the 19^th century. It is now the most common bird of prey in the country, with an estimated population of around 50,000-70,000 pairs - exceeding the sum population of all other UK diurnal raptors. Over the 5 year period from 1995 to 2000, the UK population has decreased by about 30%, the reason hasn't yet been identified (the Barn Owl is also on the decline for poorly understood reasons). On average, in the wild, a Kestrel will live for 18 months, around half dying in their first year & only just over 1/3rd surviving long enough to breed once, it is rare that they will live 10 years, but the oldest Kestrel on record from a European ringing study was 16yrs 5months old.

Falconry Terms :

Jack : Male
Kestrilet : Male

IUCN Red List Status :

Least Concern (LC)

Also Called :

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