Nieuws - 20 oktober 2010

‘Mating swifts have never been filmed on the wing’

Marion de Boo

The flight of many common or garden animals has never been filmed at high speed. So David Lentink wants to hand out high-speed cameras to members of the public.

Swallow in flight, light in a tunnel, falling maple leaf, flying fruit fly, swimming larvae, hanging hummingbird
Two weeks ago, David Lentink filmed graceful airborne fights between hoverflies and bees. In his own back garden and using his compact Casio EX F1, which can take 600 frames per second. 'I was sitting filming a bee on a flower when a hoverfly suddenly landed on her back. The bee really had to give way, after which the hoverfly took off again. In slow motion it looked a bit like a cartoon', says the researcher.
No high-speed film has been made yet of the flight of a whole range of common or garden animals. 'Fighting blackbirds would make for great short films, as would hunting behaviour in the air or the way barn swallows feed their young in a flash without even landing on the nest. Mating swifts on the wing have never been filmed either.'
Crash of the bumble bee
How effectively a pair of wings can push away the air and manipulate it to make a manoeuvre depends entirely on the shape of the wing. You can only get to grips with this by studying the wing shape very closely. Laboratory tests have shown that birds, bats and insects use the same techniques to give them added lift. 'We see a lot of convergence in nature', says Lentink. 'How a bumble bee can suddenly take off was a mystery until recently. According to all the formulas we use to design aeroplanes, it ought to crash to the ground. Only in 1996 did it become clear that bumble bees take off by generating a tremendously strong vortex above their wings, which sucks them upwards.'
Lentink graduated in aerospace engineering and went on to do a PhD in experimental biology. Last year he published an article in Science showing how the maple seed makes use of similar vortices in its flight. Lentink has also published in Nature about adjustable birds' wings. 'Thanks to laboratory tests we now know how strong vortices suck a wing upwards', says |Lentink. 'But what we still don't know is how it actually works in nature, what the flight behaviour of all those creatures is, and how it enables them to fly fast so efficiently and without wasting energy, to fly slowly, to turn in the air... We want to record all that unique flight behaviour of all those different creatures. And as a scientist that will give me new inspiration to think up more experiments.'
To the finals
The Wageningen flight experts have got through to the finals of the Annual Academic Prize. 'We want to give cameras to ordinary people so they can film all sorts of common or garden aviators in their natural environment', says David Lentink, captain of the eleven-strong campaign team. 'You can see interesting flight behaviour all around you: birds, bats, insects and seeds, even when you are just cycling around town. We'll put all the film in a freely accessible database on Youtube. That will automatically generate new research questions because up to now there are hardly any of these sorts of high-speed images of flight behaviour.'
Which of the five finalists is the winner of the Annual Academic Prize will be announced in Leiden on Wednesday 27 October. The prize is for the best project for making scientific research accessible to a wider public. The most creative communication plan will win 100,000 euros.

Beekeepers and housewives
Using small compact high-speed cameras, anyone can film out in the field. To film a bumble bee taking off from a flower, all you need is patience. The classic high-speed cameras got through reels and reels of expensive film. 'With a modern digital camera you just select the best moments and scrap the rest', says Lentink. 'Black-and-white cameras are more light-sensitive, but for a project for the general public, colour has more appeal. If we win the prize, we want to lend out 20 hand-held cameras to beekeepers, bat experts, students, housewives and anyone who is eager to film interesting flight behaviour all over the Netherlands. It is nice to get into conversation with, say, someone who knows all there is to know about ladybirds and would like to see exactly how they unfold their wings.' Participants will first follow an preparatory course with an introduction to the physics of flight. Then comes the highly professional camera, the Phantom 217, the best professional camera currently on the market, which costs about 70,000 euros and can take 7,500 frames per second. 'That looks as good as a movie and the film looks much better in slow motion', says Lentink. 'We are going to make it more user-friendly for in the field, foolproof and splashproof, with a little trolley with a lens set and extra batteries.'
Isn't it risky to lend out such an expensive camera just like that? Lentink bursts out laughing. 'You have to make sure it's properly insured and ask participants for a testimonial. But anyway, we are sponsored by the police, so I'm not really worried about that.'