Scientists believe that swallows travel an average of 500 kilometers per day. That’s a decent distance, but it seems to fly much farther: during a nine-day flight, a combination of fast combined speeds achieved a daily average of 830 kilometers.
Swallows achieved this speed during the 8,000 km journey to northern Europe that they make every spring to breed there. They can travel that great distance very quickly because they catch the insects from the air en route – so they don’t have to stop eating.
Plus, they have another trick: They get the most out of the tailwind. However, they do so not by responding to the wind as it blows at a particular moment, but by anticipating the direction of the winds as it will blow all the way in the coming days.
The Secret Backwind
Scientists have no idea how swallows do this. It might interact with air pressure, or the way weather systems go through. Either way, it gives them about 20% extra tailwind. They especially benefit from this over the Sahara and the Mediterranean. Incidentally, the flight speed of swallows in and of themselves is not exceptional compared to other migratory birds. It is mainly tailwind with on-the-go food intake that produces a high daily average.
For this research, Published At iScience, the Swallow is equipped with small tracking devices. Scientists manage to find a large percentage of the marked animals, because they go faithfully to the same breeding site every year.
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