The flight of the bumblebee may seem clumsy and slow, but new research claims these humble insects can reach altitudes higher than the peak of Mount Everest.
Despite their rotund bodies and relatively small wings, researchers from Wyoming found that bees can negotiate air so thin it would kill a human – making them the finest flyers in the insect world.
In a series of experiments, scientists placed wild bees in a flight chamber and while all managed to fly at heights of 7,500m (24,606ft), two exceed heights of 9,000m (29,528ft).
By comparison, Mount Everest’s peak sits at 8,848m (29,000ft) above sea level, and its summit is considered to be the limit of human endurance.
If this summit was just 100m higher, it would be beyond the reach of climbers. Those venturing above 8,000m (26,200ft) are said to be entering the ‘death zone’.
Dr. Michael Dillon from the University of Wyoming captured six male bumblebees in a region of China that sits 3,250m (10,600ft) above sea level.
By filming the bees in the chamber, Dr. Dillon observed that to achieve these extreme altitudes, the bumblebees increased the maximum angle at which they flapped their wings, while keeping the same beat frequency.
Forces produced by flapping wings are directly proportional to air density so organisms experience drastic reductions in lift forces in this environment.
Flying insects also exhibit the highest known demand for oxygen compared to mass, making the bumblebee’s feat even more worthy.
At 9,000m (29,528ft), air pressure is about a third of that at sea level so it is harder to fly, with less air for wings to beat against.It is also harder to breathe.
Dr Dillon said: ‘Animal flight at altitude involves substantial aerodynamic and physiological challenges. Hovering at high elevations is particularly demanding from the dual perspectives of lift and power output.
‘Nevertheless, some volant (flying) insects reside and fly at elevations in excess of 4,000m (13,100ft).
‘Here, we demonstrate alpine bumblebees possess substantial aerodynamic reserves, and can sustain hovering flight under hypobaria (at altitude) at effective elevations in excess of 9,000m (29,258ft) – higher than Mount Everest.’
Dr Dillon added: ‘The presence of such excess capacity in a high altitude bulmblebee is surprising and suggests intermittent behavioural demands for extreme flight performance supplemental to routing foraging.’
The research was published in the Royal Society journal, Biology Letters.
ANIMALS AT HIGH ALTITUDES
Some animals have adapted to live in high altitude areas, where the air is thinner.
Yaks, for example, live in the Himalayas at heights of up to 19,000ft (6,000m), and can struggle to survive at sea level.
The highest living insect is a jumping spider called the Euophrys omnisuperstes that lives at heights of up to 6,700m (22,000 feet) on Mount Everest.
Moss has been found to grow on Mount Everest at heights of 6480m (21,260 ft) and it is thought to be the highest altitude plant species in the world.
The highest flying birds are Ruppell’s Vultures, Bar-headed Geese, Whooper Swans and Bar-tailed Godwits, all of which have been recorded as flying at heights of more than 8,000m (26,200ft).
Dr. Michael Dillon from the University of Wyoming captured the six male bumblebees in a region of China that sits 3,250m (10,600ft) above sea level. Dr. Dillon said he has even found bees living in regions with altitudes of 4,800m (16,000ft).
In 2008 a colony of bumble bees were discovered on Mount Everest at more than 5,600m (18,300ft) above sea level, the highest known altitude for an insect.