Kestrel

The kestrel (Falco tinnunculus) should not by confused with its smaller American cousin (Falco sparverius) or the sparrowhawk (Accipiter nisus). The latter belongs to the family of kites, harriers and eagles, whereas the kestrel, as its Latin name suggests, is a falcon. If you see a smallish bird of prey hovering on the breeze near a British main road, there is a high chance that it is a kestrel, and none that it is a sparrowhawk, which never hovers!

Appearance

Male kestrels are about 32 centimetres in length, with the females slightly larger. The underparts are buff-colored, spotted with black, while the back and wings are reddish-brown, also with black spots. The heads of male birds are bluish-grey. The tail is quite long, and spreads into a fan shape when the bird is hovering. The wings are long and pointed. The talons and beak are sharp and pointed, as befits a bird of prey. Kestrels have excellent eyesight, enabling them to spot a beetle at a distance of 50 metres.

Behaviour

The main food of kestrels, or at least of those living in the countryside as opposed to urban environments, is voles and fieldmice. Roadside verges, with their short grass and relative lack of cover, are ideal hunting-grounds for them. Kestrels hover-hunt, which means that they will stay in one position with wings and tail outspread, making only a few adjustments to allow for changes in the wind. When its prey appears, the bird will swoop down to grab it. Passing motorists, despite the temptation to watch the kestrel at work, are best advised to keep their eyes on the road!

Hover-hunting is an energy-consuming way of earning a living as a bird, and kestrels need to eat as many as eight voles in a day. They often take these back to their perch and store them for later, preferring to do most of their eating at the end of the day, so that they can roost on a full stomach.

Their alternative feeding method is to swoop from a high perch, such as a pylon or telegraph pole. Many have adapted to city life, nesting and perching on high ledges and feeding on small birds, insects and earthworms.

Kestrels are territorial, and start to establish a small territory in February, when the pre-breeding season begins. However, they will only tend to defend the areas close to their nests, and their feeding range may well overlap with that of other pairs. Feeding territories can range from one to ten square kilometres, depending on food availability.

Breeding

Kestrels do not usually build their own nests, preferring to take over nests abandoned by other birds, such as crows. They will also nest on buildings, in holes, or even in nest boxes. The usual clutch, laid in April or May, is five to seven eggs, which are incubated for up to 30 days. The young birds are fed at first by the male kestrel (who also brings food for the female) and only later by both parents when the chicks are big enough to be left on their own. They fledge at about one month, but stay close to the parent birds throughout the summer. Most British kestrels are resident throughout the year, but there is some migration between northern and southern Europe, and even into North Africa.

Conservation

The chance of a chick living to breeding age (two years old) is only around 20%, and the life expectancy of an adult bird is only about another three years, so the long-term survival of kestrels in the UK is by no means assured. In the past, kestrels have suffered from deliberate and accidental poisoning (such as from the use of DDT as a farm pesticide), and persecution from landowners who mistakenly believe that kestrels take the chicks of gamebirds. The kestrel is now a protected species in the UK, which means that it is a criminal offence to kill kestrels or disturb their nests. 

That said, the main threats to kestrels are environmental, with farming methods being important to their survival. The presence of so many kestrels in towns and along main transport arteries is testament to the less friendly conditions in the kestrels’ traditional farmland areas. That is why the kestrel is on the amber list of bird species giving cause for concern.

© John Welford