There is a bird species in the world that spends nearly 99% of its life flying in the air. Not only eating and drinking, even mating is done in the air, the number of times it lands on the ground can be said to be only a few.
According to TTO , although small, the common swiftlet is capable of flying continuously for 10 months without stopping.
Because they do not land on the ground for a long time, their legs begin to weaken, lose strength, and even have difficulty standing. People also call them "legless birds" and they are the common swallow (A. apus).
According to IFLScience, the above special ability was tested by a research team from Lund University, Sweden.
If you look closely at the size of a swallow, you will see that its wings are very large compared to its body, the huge wings ensure that the swallow can create more lift while flying. In addition, swallows fly extremely fast, reaching a maximum speed of 110 km/h.
The team tracked 13 adult common swiftlets by attaching GPS tags to their bodies and recording their activities for two years.
The eating habits of swiftlets are very unique. They hunt insects directly in flight. Because they fly extremely fast, their bodies are also very light and their movements are also very agile. When they detect a small insect, they open their mouths wide and quickly grab the prey to eat. Their skills allow them to eat easily in the air and they can continuously replenish their energy while in the air.
The results showed that common swiftlets spend most of their time in the air, spending only 2 months on the ground to settle and breed.
When they need to land, they usually stand on a vertical surface so they can use their four claws to grab objects.
Except for a few that occasionally land on the ground, most of them spend 99.5% of their time in the sky during the remaining 10 months.
Three of them flew continuously for 10 months of migration, a particularly impressive feat given the bird's adult size: only about 20-23cm long and weighing up to 40g.
When a swallow wants to drink water, it does not need to land on the stream bank like normal birds, but opens its mouth and glides across the water to drink.
Anders Hedenstrom, a member of the research team, confirmed that 10 months is the longest period of non-landing flight ever recorded in a bird.
Scientists believe the difference between regular flying and landing swiftlets comes from their plumage.
Birds that land do not molt their wing feathers, while those that fly continuously molt during flight.
What's even more bizarre is that they even mate in mid-air. We know that most birds have only a single excretory opening, the cloaca, which is the common passageway for the three systems: digestive, urinary, and reproductive.
Another trait that helps the common swiftlet maintain this record is its extraordinary adaptability.
“The common swiftlet has evolved to be a very efficient flyer. Its streamlined body shape and long, narrow wings – creating lift with low energy expenditure,” explains Hedenstrom.
This helps common swiftlets consume less energy than other birds, and they can also speed up to catch flying insects to recharge their energy.
Scientists have also struggled with the question of how swiftlets sleep for so long, the most plausible explanation for this behavior is that they use slow-wave sleep in one hemisphere. We can think of this behavior as intermittent rest. We know that the brain is largely divided into left and right sides, and some animals can rest by putting one half of their brain to sleep and keeping the other half awake.
According to VnExpress , swiftlets can fly millions of kilometers in their average 5.5-year lifetime, moving between Europe and Africa through the seasons.
Unless the swiftlets need to feed their chicks, they will basically not choose to land. Later, once the newly hatched chicks learn to fly, they will never return to the original nest again.
"The swifts may be like frigatebirds, sleeping while gliding. They fly up to about 2-3 km above sea level at dawn and dusk and then sleep while gliding down," Hedenstrom explains.
The team also found that birds that had been in the air for nearly a year moulted, growing new tail and wing feathers while in the air. Those that had stopped at some point did not moult. The team believes this could explain the differences in their flight patterns and general condition.
KHANH LINH (t/h)
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