Kestrel Life Cycle: Nest Building To Fledging (and everything in between)
The Kestrel (Falco tinnunculus), or Common Kestrel, European Kestrel, Eurasian Kestrel or Old World Kestrel, as it is also known, is a small bird of prey which is a fairly common sight in the UK. They can often be seen hovering in mid air at the side of a country road before swooping after their prey.
This familiar action earned the Kestrel the nickname of the “windhover” in days gone by. The Kestrel is the second most common bird of prey seen in the UK after the Buzzard.
Easily recognisable by their reddish-brown back and creamy underparts speckled with black. Males have a grey head and tail which has a black band. Whereas females are similar only they lack the grey head and are a more uniform brown with dark bands on their tails.
In this article we’ll take a close look at the life cycle of the Kestrel, from egg laying to fledging and much more besides.
Table of Contents
How Long Does A Kestrel Live?
Most Kestrels die before they reach the age of 2 years and mortality rates up until their first birthday can be as high as 70%. However, there are some Kestrels that live long lives with those that make it past their 2nd birthday often achieving almost 16 years of age.
There are exceptions to this rule with one individual living for as long as 24 years according to ring records.
How Fast Can A Kestrel Fly?
Kestrels can reach speeds of up to 37 miles per hour (59.5 km/h) when they need to. But they spend much of their time hovering over fields in an almost stationary position as they search for prey on the ground around 30 to 60 feet (10 to 20 metres) below.
They have developed and evolved to a point where they can keep their head still whilst their wings are flapping at a rapid speed to keep them in the same position. Their eyes never leave the ground allowing them to track and follow their prey from above, before they swoop down.
Are Kestrels Aggressive?
Kestrels are not particularly aggressive towards other birds or humans. Unless they are protecting their nests, eggs, or chicks. They hunt alone and are often found nesting in loose colonies with other Kestrel pairs which suggests that they are at least tolerant of other birds.
However, like most birds of prey, they do exhibit assertive behaviour when defending their nesting sites.
What Is A Kestrel’s Habitat?
Kestrels can be found all across the UK in areas of grassland, farmland, heathland and shrubland. They don’t need woodland as long as there are other perching and nesting sites available like rocks or even buildings.
They tend to hunt in open spaces with long grass which is where their primary food source, the vole resides. They don’t often venture into woodlands but will hunt on the edges of woods.
How Long Does It Take For A Kestrel To Build A Nest?
Kestrels don’t build nests as such, they prefer nesting on cliff ledges or buildings, in holes in trees and will even use old nests left behind by other birds (mainly Corvids).
This means that any time needed to build a nest is spent searching for an existing nest in a good location. So we can estimate that it takes anywhere from a few hours to a day for a Kestrel to find a nest and move in.
Eggs
Now let’s look at the next important stage in the life cycle of the Kestrel, the eggs. We’ll find out when Kestrels lay their eggs, how many they lay, what the eggs look like as well as how long it takes for them to hatch.
When Do Kestrels Lay Eggs?
Kestrels typically lay their eggs between April and May. The exact timing for egg laying is dependent on climatic conditions and food availability. But eggs are generally laid between mid April to mid May.
How Many Eggs Does A Kestrel Lay?
Kestrels can lay anywhere between 3 to 6 eggs with an average clutch containing 4 to 5. If vole populations are good, Kestrels often lay 7 or 8 eggs.
Most early clutches tend to be larger, typically 5 to 6 eggs while later clutches tend to be smaller around 3 to 4.
What Do Kestrel Eggs Look Like?
Kestrel eggs are smooth, non-glossy, oval shaped and usually a white or yellowish-buff colour with reddish-brown markings. Each egg is around 39 x 31 mm in size and weighs around 21 grams with 8% of that weight being the weight of the shell.
Interestingly, the first egg laid usually has a deeper colour and more markings while the last egg laid is often paler than the rest.
How Long Do Kestrel Eggs Take To Hatch?
The eggs are incubated mainly by the female although the male does occasionally help out. They hatch after around 28 to 29 days of careful nurturing where they are turned regularly to prevent the embryo from sticking to the shell.
Chicks
Once the eggs hatch, we move on to the next stage in the life cycle of the Kestrel, the chicks.
How Many Chicks Does A Kestrel Have?
In an ideal world, the number of chicks that a Kestrel has should correspond with the number of eggs laid. However, many eggs don’t make it to the hatching stage.
Some are unfertilised while others are not turned frequently enough to allow the embryo to develop properly. It is estimated that somewhere between 60 and 80% of Kestrel eggs don’t hatch.
This means that from 4 or 5 eggs, we can expect somewhere between 1 to 3 chicks to hatch.
When Do Kestrel Chicks Open Their Eyes?
Kestrel chicks open their eyes about 5 to 7 days after hatching. When they first hatch, they are blind, naked and completely reliant on their parents for everything.
These altricial chicks develop quickly, and within a few weeks, they start growing feathers and developing more independence.
When Do Kestrel Chicks Fledge?
The fledging period for Kestrels is around 27 to 32 days after hatching. At first, they just take short flights and are still reliant on their parents for food and support.
Their parents show them how to hunt and track their food and how to catch their prey. The fledglings reach full independence about 4 to 6 weeks after they fledge.
SEE ALSO: Marsh Harrier Diet and Size: Feeding Habits, Predators, and Measurements
Frequently Asked Questions
The average lifespan of a Kestrel is around 2 years and mortality rates up until their first birthday can be as high as 70%. However, there are some Kestrels that live long lives with those that make it past their 2nd birthday often achieving almost 16 years of age or more.
Kestrel eggs are a white or yellowish-buff colour with reddish-brown markings. Each egg is around 39 x 31 mm in size and weighs around 21 grams.
Kestrel chicks fledge or take their first flight when they are around 27 to 32 days old. Even after fledging, they still rely on their parents for food until they learn how to hunt themselves.
