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Supercharged swifts take flight speed record
By Jody Bourton
Earth News reporter

Common swift
Frequent fast flyer?

A common swift has taken the title as the fasted bird recorded in level flight.

The swift (Apus apus) can power itself to a speed of 111.6km/h (69.3mph) flying horizontally and even upwards.

Other birds, such as peregrine falcons, fly faster while diving in a stoop, but the swift is the fastest accurately recorded flying under its own power.

The birds reach top speed during bouts of mating known as 'screaming parties', say scientists.

Details of the bird's high speeds are reported in the Journal of Avian Biology.

It is remarkable that a bird that appears to be 'finely tuned' is able to fly more than twice as fast when it needs to
Dr Per Henningsson
Lund University, Sweden

Many species of bird lay claim to be speedsters of the sky.

The fastest bird of all is widely acknowledged to be the peregrine falcon (Falco peregrinus).

During a stoop it can reach speeds in excess of 300km/h (83.3m/s; 186mph). But it can only do this by freefalling, harnessing the force of gravity.

Last year, scientists recorded male Anna's hummingbirds reaching speeds of 97.2km/h (27m/s; 60.4mph) during diving courtship displays in front of females, an extreme speed considering the bird's tiny size.

However, flying fast in level flight takes much more effort.

A relative of the common swift, the white-throated needletail, also known as the needle-tailed swift or spine-tailed swift (Hirundapus caudacutus) is commonly reported as the fastest bird in level flight.

A 'screaming party' of swifts flies by at record speed

It is reported to reach a top speed of 169km/h (47m/s; 105mph).

But the record is difficult to verify as the methods used to measure the bird's speed have never been published, says avian flight specialist Dr Per Henningsson of Lund University in Sweden.

Confirmation of the new record came as Dr Henningsson and Lund University colleagues Dr Christoffer Johansson and Professor Anders Hedenstrom filmed common swifts using two high speed cameras.

Using this equipment they were able to deduce the bird's flight speed and wing-beat frequency.

Need for speed

During the study, they clocked common swifts flying at 75km/h (20.8m/s; 47mph), with one swift registering a top speed of 111.6km/h (31m/s; 69.3mph).

That is the highest confirmed speed achieved by a bird in level flight, the researchers say.

Extraordinarily, the birds occasionally reached top speed while performing steep climbing flights.

FAST FLYERS
Common swift

Also surprising is the circumstances in which the swifts fly so fast.

Usually, common swifts fly at a relatively consistent speed of 36 to 43km/h (10 to 12m/s; 22 to 26mph), regardless of whether they are flying to a roost, migrating or flying in a wind tunnel, says Dr Henningsson.

But the birds "turboboost" their speed when they are showing off.

When common swifts come together to mate, both breeders and non-breeders fly together in a social display, which scientists call "screaming parties" based on the vocalisations the birds emit.

"They were generally known for flying very fast during this behaviour," says Dr Henningsson.

"However, there were no really certain measurements of how fast these flights are.

"It is remarkable that a bird that otherwise appears to be 'finely tuned' to perform at a narrow range of flight speeds at the same time is able to fly more than twice as fast when it needs to."

That means the birds need to be able to radically alter their aerodynamic performance, by altering their wing profile and physiology, depending on whether they are flying normally or in a screaming party.

Other bird species can dramatically change their flight capabilities: for example chickens rarely take to the air, but they are capable of short, explosive bursts of flight when spooked.



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