Swift Life Cycle: Nest Building To Fledging (and everything in between)

The Swift is a medium sized bird that looks similar to a slightly larger Swallow or House Martin. However, Swifts are members of a different bird family altogether. In fact, the nearest relatives to the Swift are Hummingbirds.

Swifts have short legs which are used mainly for clinging onto walls and other vertical surfaces. These master flyers never spend much time on the ground where they would be vulnerable. They often spend as long as 10 months in continuous flight, even sleeping whilst flying.

To find out more about these fascinating birds, keep reading.

How Long Does A Swift Live?

Considering their propensity for continuous flight, Swifts live a surprisingly long time. The average lifespan of a Swift is around 5.5 years.

However there have been individuals that have lived for as long as 21 years according to ring records.

How Fast Can A Swift Fly?

The only time a Swift isn’t flying is when they are nesting. This means that Swifts can be flying for 10 months without ever landing. They can reach speeds of up to 69 mph (111 km/h) which is almost 31 metres per second (30.84 m/s).

They feed as they fly, catch nesting material as they fly and even sleep as they fly.

Are Swifts Aggressive?

Swifts are extremely aggressive birds especially when it comes to protecting their nesting sites. If a fight between 2 Swifts breaks out it can be violent and involves the use of claws and bills.

This can often lead to serious injury or even death of one of the combatants. The main cause of these violent exchanges is the lack of suitable nesting sites. Swifts traditionally nest in disused Woodpecker holes and will often return to the same hole each breeding season.

Younglings who are nesting for the first time find a nesting hole and try to enter only to be attacked by the historic keeper of the nest. Swifts will defend their nests from all comers and these epic battles can become quite gory.

What Is A Swift’s Habitat?

Swifts are known for their long distance migrations, travelling from their breeding grounds in the UK to their wintering grounds in Africa. In the UK they prefer to nest in wetlands and grasslands using old, disused Woodpecker holes as their nests.

They will also nest in urban and suburban areas using small gaps in buildings like under eaves. They particularly like old churches and other historic buildings to nest in.

How Long Does It Take For A Swift To Build A Nest?

Young Swifts can remain in the air flying for up to 2 or 3 years until they reach sexual maturity at around the age of 3 or 4. It will take an average of anywhere between 1 to 3 weeks for a Swift to build a nest.

The actual time taken will depend on the weather, the availability of suitable nesting materials and the experience of the birds. The nests are built in crevices on cliffs, in buildings or in trees; they will sometimes use nesting boxes as well.

The birds use materials like plant matter, pieces of debris and feathers which they catch as they fly. These materials are bound together with saliva to form a nest.

As Swifts return to the same nesting sites every year, they often repair or refit existing nests. This can decrease the length of time taken to build the nest.

Eggs

Once the nest has been built, the female will lay her eggs.

When Do Swifts Lay Eggs?

Swifts typically lay their eggs between May and June. The exact time depends on climatic conditions and the geographical location of the nest.

In warmer areas, they might lay their eggs in May but in cooler areas, it might be June before the egg laying begins.

How Many Eggs Does A Swift Lay?

The female Swift will lay one brood of eggs each season with a clutch size ranging from 1 to 4 eggs. An average clutch contains 2 to 3 eggs but it all depends on the health and experience of the female.

What Do Swift Eggs Look Like?

Swift eggs are small, white and oval shaped. They have a slightly rough texture and are pure white in colour with no markings or blemishes. 

Each egg is around 25 x 16 mm in size and weighs around 3.5 grams.

How Long Do Swift Eggs Take To Hatch?

The eggs are incubated by both parents in turn for around 19 to 20 days. During this incubation period, the parents are both attentive and will only leave the nest for short periods of time to feed.

Chicks

Once the eggs hatch, we move on to the next stage in the reproductive cycle of the Swift, the chicks.

How Many Chicks Does A Swift Have?

The number of chicks a pair of Swifts has should correspond to the number of eggs laid. Swifts tend to have an 80% survival rate from eggs to chicks. 

This means that from a clutch of 4 eggs, 3 should develop to the hatching stage.

When Do Swift Chicks Open Their Eyes?

The chicks are altricial which means they are blind and naked after hatching. Their parents have to feed them and regulate their temperature. The chicks will usually open their eyes around days 4 to 6. 

This is a crucial stage in the development of the chicks and enables them to start to become aware of their surroundings. An interesting fact about young Swifts is their ability to survive without food for around 48 hours. They do this by lapsing into a semi-torpid state.

When Do Swift Chicks Fledge?

As the chicks grow and develop, they start to develop their true feathers including their flight feathers. Swift chicks typically leave the nest after around 40 days.

They literally drop from the nest and then begin to fly before hitting the ground. As soon as the chicks fledge the nest, the parents leave too and start their long migratory journey back to Africa to overwinter.

SEE ALSO: Smew Life Cycle: Nest Building To Fledging (and everything in between)

Frequently Asked Questions