Swift Diet and Size: Feeding Habits, Predators, and Measurements

Swifts are built for flying and spend most of their lives in the air. They only stop flying when they enter their nests to care for their eggs and raise their chicks. Even during the hours of darkness, they fall asleep on the wing and allow the wind to carry them.

They feed whilst in the air and even mate whilst flying. Keep reading to find out more about these fascinating birds.

The Dietary Habits Of The Swift

Swifts are insectivores and feed as they fly, catching any flying insects that happen to be in the vicinity.

What Does A Swift Eat?

Swifts eat any type of flying insects including; mosquitoes, aphids, flies, beetles, flying ants, moths, wasps, bees, hornets, and butterflies. They can also catch any spiders suspended from their web-like threads.

Swift can go up to 14 days without food which allows them to survive during periods of inclement weather when insects are scarce. They get into a kind of semi-torpid condition where their energy requirements are greatly reduced.

They follow rain clouds because there are often an abundance of insects in the unstable air just to the rear of a weather depression.

What To Feed A Baby Swift? 

Adult Swifts catch insects in the air and form them into a compact ball which is known as a “bolus”. The bolus is held together with saliva and can contain hundreds of insects. It is brought back to the nest and fed to the chicks.

The chicks tend to get fed multiple times during the day but the frequency of feeding varies depending on the age of the chicks and the availability of suitable foods.

The high protein diet fed to the chicks is essential for their steady growth and development. If you were to find a young Swift outside of the nest, it is best to not touch it and contact your local RSPB site.

It is not easy raising a wild bird and the RSPB will have the necessary skills to give the bird its best chance of survival.

Breeding Habits Of Swifts

The breeding habits of the Swift are adapted to their aerial lifestyle. The pair will form synchronised flying displays whilst calling to each other with their high-pitched screams.

They will copulate as they fly and only stop flying in order to make a nest, lay their eggs and care for their young.

Do Swifts Mate For Life?

Swifts are known to form long-term pairs which means that for the most part, Swifts do mate for life. They will return to the same nesting site each year with the same partner.

There hasn’t been enough scientific study into the life of the Swift to know whether the pair spend all of the year together or just meet up at the nesting site.

The Size & Weight Of Swifts

Swifts are small, lightweight birds perfectly suited to their aerial lifestyle.

How Much Does A Swift Weigh?

Swifts weigh around 36 to 50 grams which is roughly the same as a Cadbury’s creme egg.

How Big Is A Swift?

Swifts are around 16 to 17 cm long with a wingspan of around 42 to 48 cm. With their forked tail and almost inverted “W” shape, Swifts are easily recognisable when flying through the sky.

Are Swifts Under Threat?

Although considered to be a bird of least concern by the International Union for Conservation of Nature (IUCN), the Swift is facing various threats that have led to concerns about their population. There has been a noticeable decline in their numbers in many regions and in Europe in particular.

These threats include; a loss of nesting sites due to urban redevelopment and building renovations, habitat loss like the destruction of woodlands, grasslands and wetlands and the increased use of pesticides has led to a significant shortage of insects and suitable nesting and feeding sites, climate change also affects insect numbers and disrupting weather patterns can result in their untimely arrival at nesting or overwintering sites.

Another reason for their declining numbers is pollution which can affect insect populations as well as the health of young Swift chicks.

What Eats A Swift?

As Swifts spend most of their time in the air, they have few natural predators and become most vulnerable during the breeding season. With that said, Swifts often fall prey to Peregrine Falcons, Hobbies, Barn Owls, Tawny Owls and some of the larger members of the Gull family.

When nesting in old buildings, Swifts can often become the prey of domestic cats. This is especially true in urban areas where cats are more prevalent.

However, the speed and agility of the Swift and the relative inaccessibility of their nests helps to protect them from many potential threats and predators.

Where Can I See Swifts In The UK?

Swifts can be seen in a wide range of locations all across the UK especially in areas where there are large numbers of flying insects and a mixture of old buildings and open spaces. You can often see Swifts in urban areas like cities and towns where they nest in the eaves of old buildings. Places like;

• London
• Manchester
• Birmingham
• Glasgow
• Edinburgh
• Oxford
• Cambridge
• Bath
• York
• East Anglia
• The Cotswolds
• Brighton
• Dorset
• Cornwall
• The Scottish Highlands & Islands
• The Norfolk Broads
• The Lake District
• The Fens

Swifts can also be spotted on nature reserves like;

• RSPB Minsmere
• RSPB Leighton Moss

Swifts are most active during the evening and early morning as they feed on flying insects. You will have a better chance of seeing Swifts during their migration periods of late April and May and late July and August.

Listen out for their high-pitched calls and watch for their impressive aerial acrobatics.

SEE ALSO: Bewick’s Swan Life Cycle: Nest Building To Fledging (and everything in between)

Frequently Asked Questions