Kestrels are one of the smallest birds of prey, but also one of the most widespread, and are frequently seen hovering beside motorways or perched on telephone wires watching for prey. In recent years they have become well adapted to living in urban environments as well as their traditional moorland and farmland habitats.
Our guide to the breeding and nesting habits of kestrels in the UK takes an in-depth look at what kind of nest sites they choose, when kestrels lay eggs and how many broods they raise in a typical year. Read on to find out the answers to these questions and more.
Kestrels are widespread throughout the UK and no longer have a ‘typical’ habitat. They have adapted well to urban settings, and can be seen hunting in towns and city centres, as well as beside busy motorways, over farmland and in rural areas with moors and heaths. The only place where the species is not commonly found is in densely forested areas.
Kestrels’ home ranges tend to include a small area immediately around their nest, and a wider hunting range of between 1 and 10 km further afield. Nest sites vary from the disused treetop nests of other birds to ledges, cavities and sometimes artificial nest boxes.
A pair of Kestrel chicks inside a nest in the cavity of a tree
Once a suitable nest has been found, it will frequently be used time and time again by a kestrel pair in successive years, with some nests in use every breeding season for a decade or more. However, an annual ‘site selection’ process occurs between pairs ahead of breeding each year, to ensure the chosen chick-raising location is still the best available site.
It is possible for a kestrel pair to set up home in a back garden, but not particularly common. If your garden is already home to an existing nest previously used by crows or jays, for example, this could make it an attractive prospect for a house-hunting kestrel pair.
Another factor is the proximity to a supply of small mammals, particularly voles, as a kestrel’s hunting range is usually fairly small in area around its nest site.
It’s not unheard of for kestrels to set up home in the roof space of a disused garage or shed, or even in a planter or hanging basket on a balcony, as long as it is not in a spot where it will be regularly disturbed by the presence of humans or vehicles, and there are feeding opportunities within easy reach.
Kestrel nesting in a nest box
Kestrels do regularly make use of suitably positioned nest boxes that are designed especially for the species. Open-fronted large wooden boxes, mounted high on a wall, tree or pole offer an ideal sheltered space in which kestrels can lay their eggs and raise their young.
Nests originally built by corvids are frequently reused by kestrels for their own broods. These can be found in a range of trees, including both coniferous and deciduous varieties. Nest spots in the upper branches of the canopy are chosen, and trees on the edges of wooded areas are frequently used, rather than any deeper into a forest.
Kestrels commonly make use of disused cavities in tree trunks that have been used by other birds before them, and again, these are found in a variety of different tree species, and not limited to one particular type.
Female Kestrel with her chicks in a nest up a tree
Kestrels don’t build their own nests, but make use of any suitable site they happen to discover. This could be a stick nest that has been previously built and used by crows or rooks, a cavity in a tree trunk, or a rocky ledge or rooftop.
As kestrels do not build their own nests, there’s no ‘typical’ measurements for the sites in which they choose to lay their eggs or raise their young.
Kestrel chicks grow fairly quickly, so reasonably large stick platform nests are needed if this is the option they go for.
Nests that have supported corvids to raise their young are often reused by breeding kestrels as they offer sufficient room for growing kestrel chicks without the risk of becoming overcrowded.
Young Common Kestrels inside of a nest box
Kestrels begin to establish their breeding territories early in the year, searching for a suitable nesting spot from as early as February.
Male and female pairs tend to spend winters apart, but reunite each breeding season ahead of the spring, and a period of courtship follows, where they revisit nest sites to select their preferred spot.
Once a nest site has been chosen, mating occurs and eggs are typically laid between April and May.
A brood of 3 to 6 eggs is laid in late April to early May. The incubation period lasts for around 4 weeks, and chicks are brooded in the nest by the female for a further 2 weeks. During this time, the male is responsible for bringing food to the female and, later, the chicks.
Once the young are sufficiently developed to be able to regulate their own body temperatures and no longer need the constant brooding warmth offered by their mother, they remain in the nest for up to two more weeks before they are ready to fledge.
After fledging they continue to return to the nest for food and overnight shelter, and become fully independent around a month later.
Kestrels usually lay eggs between late April and early May. In years where cold weather extends further into spring, it’s more likely for eggs to be laid into May, as pairs will delay nesting until food supply is more abundant.
Kestrels nest in a range of places, including holes in cliffs
Kestrels are opportunistic nesters and never construct their own nests from scratch. They make use of nests that other birds, particularly corvids, have previously built and since abandoned. Kestrels are also frequent users of cavity nests and will use disused tree hollows originally excavated by woodpeckers.
Common Kestrel chicks inside the nest
Kestrel eggs are a buffish colour, blotched with streaky brown-black markings and smooth shells. They are slightly rounded, measuring around 4.5 cm (1.8 in) in length.
A typical brood for a kestrel contains between 3 and 7 eggs, with eggs being laid at two-day intervals until the clutch is complete. Four to five eggs is the most common clutch size.
Incubating eggs is the sole responsibility of a female kestrel. For around 27 to 29 days, the female does not leave her unhatched eggs, and relies on the male partner to bring food to the nest site.
For a further 10 to 14 days after hatching, young kestrel chicks continued to be brooded on the nest by the female, with the male providing food for the mother and the young at this time.
Actual feeding of young is undertaken by the female, who tears apart the prey brought to the nest by the male into manageable pieces for the nestlings to digest.
Close up of three Kestrel eggs inside the nest
Around a month after hatching, young kestrels are ready to begin their journey towards independence. They fledge at between 27 and 35 days and spend time exploring the area surrounding the nest site, but continue to return to the nest to be fed and to roost safely overnight.
After a further month of growing more experienced and confident in their surroundings, they begin to become more independent, and prepare to form their own territories.
These territories may overlap with those of their parents, although this does not cause conflict as the species is not overly territorial.
Only one brood each season is normal for kestrel pairs. In seasons where food is not plentiful, kestrels may not attempt nesting at all. If an initial attempt fails early enough in the season, a further clutch may be laid.
Close up of a perched Kestrel fledgling
If a kestrel’s nest fails during the incubation period, they will most likely abandon the nest and not proceed with nesting that year. In a season where food supplies are scarce, for example when there is a shortage of voles, pairs may not breed at all rather than attempt to breed and not be able to successfully provide enough food for their young.
Nests used by kestrels are typically around 10-20 m (35-65 ft) off the ground, giving them a perfect vantage point for spotting nearby prey and reducing the chance of predation of their eggs or chicks. Nesting on the ground is not observed in this species.
On cold winter nights, kestrels have been observed to roost overnight in artificial nest boxes mounted on trees or the sides of buildings. Roosting spots that offer shelter are used, including holes in disused buildings, upper branches of trees and ledges or roof cavities of barns or other farm buildings.
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