Giant condors can travel over 100 miles without flapping their wings as the world’s heaviest soaring birds spend most of their time gliding on thermal updrafts
- Scientists based in Argentina attached tracking devices to the Andean condor
- The heaviest known soaring bird flapped only 1.3 per cent of its total flight time
- One of the tracked birds covered a distance of about 105 miles without flapping
Giant condors can travel more than 100 miles without flapping their wings and instead spend most of their time gliding on thermal updrafts, new research shows.
UK biologists deployed logging devices on the Andean condor (Vultur gryphus), the heaviest known soaring bird, to show how it flies with limited flapping.
Incredibly, one bird flew continuously for more than five hours, covering more than 105 miles (170km) without flapping.
And the condors flapped for only 1 per cent of their flight time, specifically during takeoff and when close to the ground.
This incredible skill puts the species among the vertebrates that expel the lowest levels of exertion during movement.
An Andean condor soars above the Patagonian steppe in Argentina. Emily Shepard and colleagues examined how the Andean condor, the heaviest known soaring bird, can fly with limited flapping
The results are particularly striking as the birds tracked in the study were juveniles, showing that even inexperienced birds can cover vast distances over land without flapping.
Overall, this can help explain how extinct birds with twice the wingspan of condors could have flown.
‘Our data reveal the lowest levels of flapping flight recorded for any free-ranging bird, with condors remarkably spending 99 per cent of all flight time in soaring or gliding flight,’ wrote Emily Shepard, a professor of Biosciences at the University of Swansea, and her colleagues in the journal PNAS.
‘The extraordinary low investment in flapping flight was seen in all individuals, which is notable, as none were adult birds.
‘Therefore, even relatively inexperienced birds operate for hours with a minimal need to flap.’
Scientists equipped the eight immature condors in the Andes near San Carlos de Bariloche, Argentina
Ethogram of flight types within a single flight, classified according to the rate of change in altitude. Flight behaviours marked by colour. Blue: gliding; orange: slope soaring; pink: thermal soaring
The Andean condor ranks in the top 10 for largest living bird wingspans, at around 11 feet or 3.3 metres.
The species weighs up to 15kg and some of the other largest soaring birds weigh up to almost 16kg.
But extinct terrestrial birds were much larger – the largest, the Giant Teratorn, is estimated to have weighed around 72kg or more.
It has always been assumed that the Giant Teratorn would have been incapable of sustained flapping flight and was entirely dependent on soaring.
Almost nothing is known about the amount of flapping flight required for daily foraging movements in large soaring birds of the modern day, the researchers say.
To learn more, the team equipped the eight immature condors in the Andes near Bariloche, Argentina with what they called custom-made ‘flight recorder’ devices in multiple field seasons from 2013 to 2018.
They found that the birds flapped for 1.3 per cent of the total recorded flight time and spent the rest of the time gliding and soaring through the air.
More than 75 per cent of flapping was associated with the take-off, highlighting how little this process is needed once the species is in the air.
Condors can sustain soaring across a wide range of wind and thermal conditions, flapping for only 1 per cent of their flight time
Flapping was also most frequent in early morning, when thermal updrafts begin to form and as the air generally rises slowly.
But even during winter, when soaring conditions are poor, Andean condors may flap for no more than approximately two seconds per kilometer, the team predict based on the data.
Flying animals ‘extract energy’ from the environment by soaring, and use this energy to support the metabolic costs of flapping in flight, the team say.
Pictured, an Andean condor. The largest extant soaring birds weigh up to almost 16 kg (25), but extinct terrestrial birds were much larger, with the largest, Argentavis magnificens, estimated to have weighed ∼72 kg or more
Flight capacities in animals are therefore fundamentally linked to the characteristics of air currents and this affects large-scale patterns of how they use air space.
For instance, birds of the order Passeriformes tune their migration decisions in relation to the wind and use particular migration flyways that are not necessarily associated with the shortest route, the researchers say.
But for the very largest flying birds, the dependence on soaring is so crucial that their distributions may even be constrained by the availability of updrafts.
Large soaring birds are most likely to flap to remain airborne or increase speed at times when they are unable to soar.
The team admit that their results relate to movement within a restricted longitudinal range and that ‘it is unclear how flight effort would vary outside this’.
ANDEAN CONDOR HAS ONE OF THE LARGEST WINGSPANS IN THE WORLD
Andean condors (Vultur gryphus) inhabit most of western South America in the mountains and deserts.
Andean condors can be found in Colombia, Bolivia, Ecuador, Peru, Chile, and Argentina.
The species inhabit mountain and coastal mountain habitat types in the Andean mountains of South America.
They have been located at elevations of up to 18,000 feet.
They prefer areas with wide open spaces which aid in their detection of food.
Andean condors roost and nest on cliff faces in small rock ledges or caves.
They use the thermals that rise and spiral off of these cliff faces to soar for hours with very little effort, scanning for decaying flesh of dead animals.
Andean condors have dark feathers in maturity, while juveniles are olive-grey and brown).
They have a white collar or downy plumage around the base of their necks.
They also have white flight feathers on their wings as adults, with those of the male being more pronounced.
When extended, the wing tips have gaps between the primaries which is an adaptation for soaring.
The head and neck of adult condors are bare of feathers and are generally black to dark reddish brown, while juveniles have much darker skin and young hatchlings have fluffy grey down on their bodies.
This baldness is presumably a hygienic adaptation, as the bare skin is easier to keep clean and dry after feeding on carrion.
The beak is hooked at the end and functions in tearing rotting meat off a corpse.
*The bases of their upper and lower mandibles are dark with the rest of the beak being ivory colored.
Andean condors weigh between 7.7 and 15 kg and range from 38 to 50 inches in length.
Their wingspan of 3.3 metres or around 10.8 feet is the longest wingspan of any land bird.
This is only exceeded only by the wingspans of four seabirds and water birds.
The feet of Andean condors are much less powerful with shorter blunted talons compared to those of other birds of prey.
This adaption is well suited for a lifestyle of walking and scavenging.
Source: University of Michigan
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