The Common Kestrel (Falco tinnunculus) is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European Kestrel, Eurasian Kestrel, or Old World Kestrel. In Britain, where no other brown falcon occurs, it is generally just called "the Kestrel".
This species occurs over a large range. It is widespread in Europe, Asia, and Africa, as well as occasionally reaching the east coast of North America. The Common Kestrel is small compared with other birds of prey, but larger than most songbirds. Kestrels have long wings as well as a distinctive long tail like the other Falco species. This bird's plumage is mainly brown with dark spots. Unlike most hawks they display sexual colour dimorphism with the male having a blue-grey head and tail. The tail is brown with black bars in females, and has a black tip with a narrow white rim in both sexes. All Common Kestrels sexes have a prominent black malar stripe like their closest relatives.
Common Kestrel eggs
Common Kestrels measure 34 "? 38 cm (~13 "? 15 in) from head to tail, with a wingspan of 70 "? 80 cm (~27 "? 31 in). The average adult male weighs around 155 g (~5˝ oz) with the adult female weighing around 184 g (~6˝ oz).
This is a diurnal animal and prefers an "open country" habitat such as fields, heaths, and marshland. When hunting, the Common Kestrel hovers about 10 "? 20 m (?33 "? 66 ft) above the ground, searching for prey, usually by flying into the wind or using thermals from ridges. Once prey is sighted, the bird makes a short, steep dive toward the target. It can often be found hunting along the sides of roads and motorways. It has recently been shown that it is able to see near ultraviolet light, allowing it to detect the urine trails around rodent burrows, which reflect ultraviolet light.
Kestrels prey upon small mammals, including voles, as well as small birds, large insects, earthworms, and frogs. Like most birds of prey, Kestrels have keen eyesight enabling them to spot small prey from a distance. Kestrels require the equivalent of 4-8 voles a day, depending on energy expenditure (time of the year, amount of hovering, etc). They have been known to catch several voles in succession and to store some for later consumption.
In built-up areas Kestrels will often nest on buildings or reuse the old nests of crows.
Evolution and systematics
This species is part of a clade that contains the kestrel species with black malar stripes, a feature which apparently was not present in the most ancestral kestrels. They seem to have radiated in the Gelasian (Late Pliocene, roughly 2.5-2 mya, probably starting in tropical East Africa, as indicated by mtDNA cytochrome b sequence data analysis and considerations of biogeography. The present species' closest living relative is apparently the Nankeen or Australian Kestrel, which probably derived from ancestral Common Kestrels settling in Australia and adapting to local conditions less than one million years ago, during the Middle Pleistocene. See Groombridge et al. (2002) for thorough discussion of Common Kestrel and relatives' divergence times. The Lesser Kestrel, which much resembles a small Common Kestrel with no black on the upperside except wing and tail tips, is probably not very closely related to the present species, and the American Kestrel is apparently not a true kestrel at all (Groombridge et al. 2002). Both species have much grey in their wings in males, which does not occur in the Common Kestrel or its close living relatives but does in almost all other falcons.
A number of subspecies of the Common Kestrel are known (Orta 1994). Most of these differ little, and mainly in accordance with Bergmann's and Gloger's Rules. Tropical African forms have less grey in the male plumage.
The Rock Kestrel may be a distinct species, more distantly related than the Nankeen Kestrel - and its relationship to the other African and South Asian taxa needs more study.
The Canary Islands subspecies are apparently independently derived from Continental birds (Groombridge et al. 2002).
- Falco tinnunculus tinnunculus Linnaeus, 1758
Temperate areas of Europe, North Africa, the Middle East, and Asia north of the Hindu Kush-Himalaya mountain ranges to the NW Sea of Okhotsk region. Northern Asian populations migrate south in winter, apparently not crossing the Himalayas but diverting to the west.
- Falco (tinnunculus) rupicolus Daudin, 1800 - Rock Kestrel
NW Angola and S Zaire to S Tanzania, and south to South Africa. Probably a distinct species, but its limits with rufescens require further study. It differs markedly from the other subspecies of the F. tinnunculus complex. In particular, the females have what in other subspecies are typically male characteristics such as a grey head and tail, and spotted rather than barred upperparts. The Rock Kestrel has less heavily marked, brighter chestnut upperparts and its underparts are also a bright chestnut that contrasts with the nearly unmarked white underwings. Females tend to have more black bands in the central tail feathers than males. The open mountain habitat is also atypical for Common Kestrel.
- Falco tinnunculus rufescens Swainson, 1837
Sahel east to Ethiopia, southwards around Congo basin to S Tanzania and NE Angola.
- Falco tinnunculus interstictus McClelland, 1840
Breeds East Asia from Tibet to Korea and Japan, south into Indochina. Winters to the south of its breeding range, from India to the Philippines.
- Falco tinnunculus rupicolaeformis (C. L. Brehm, 1855)
Arabian Peninsula except in the desert and across the Red Sea into Africa.
- Falco tinnunculus neglectus Schlegel, 1873
Northern Cape Verde Islands.
- Falco tinnunculus canariensis (Koenig, 1890)
Madeira and western Canary Islands. The more ancient Canaries subspecies.
- Falco tinnunculus dacotiae Hartert, 1913 - Local name: sarnicolo
Eastern Canary Islands: Fuerteventura, Lanzarote, Chinijo Archipelago. A more recently-evolved subspecies than canariensis.
- Falco tinnunculus objurgatus (Baker, 1929)
Western and Eastern Ghats of India; Sri Lanka.
- Falco tinnunculus archerii (Hartert & Neumann, 1932)
Somalia coastal Kenya, and Socotra
- Falco tinnunculus alexandri Bourne, 1955
Southwestern Cape Verde Islands.
Not globally threatened, the diminutive subspecies dacotiae is quite rare, numbering less than 1000 adult birds in 1990 (Orta 1994). It is peculiar for nesting occasionally in the dried fronds below the top of palm trees, apparently coexisting rather peacefully with sparrows and other small birds which also make their home there (Álamo Távio 1975).
The Late Pliocene to Middle Pleistocene ice age Common Kestrels of Europe differed slightly in size from the current population; they are sometimes referred to as paleosubspecies Falco tinnunculus atavus (see also Bergmann's Rule).
Young male during ringing
Perched close to nesting site
Head & shoulders view