When people go on long journeys they use compasses and maps to make sure they will arrive the planed location. Do birds use any “instruments” when migrating to help them infallibly reach the same destination year after year?
It is known that birds orientate themselves using the position of the sun and the stars, and some scientific experiments showed that birds sense changes in the earth‘s magnetic field. Birds can also sense the smell of the sea and the sound of the waves and wind, which also help them to navigate. Bird navigation, that still cannot be fully explained, is based on a variety of senses.
Birds have one more great ability they use when go on a long trip – they can predict weather (they can sense changes in atmospheric pressure). Some experiments the scientists have conducted in order to figure out how birds react to what’s going on around them, showed that birds react to changes in atmospheric pressure between the floor and the ceiling of a laboratory. Its interesting that some birds have sensed the change before it even occurred.
Some birds, like the pigeon, have an amazing ability to detect polarized light (light waves that vibrate in one direction) as well as ultraviolet light, which they use when flying. The pigeon can also do one great thing we humans can’t – to hear infrasound that comes from ocean waves, storms, mountain winds, earthquakes… In a study conducted in the east of USA, scientists noticed the pigeons react to storm that occurs on the other side of the country! It’s clear that such a good sense of hearing help pigeons to orient during the flight. You all know the pigeons were used to carry messages in the past, and now you know why.
Blackcap (Sylvia atricapilla)
When it comes to migration, little bird Blackcap (Sylvia atricapilla) flies 3.700 km (2.300 miles) finding no time to take a rest. During the flight this bird spends 86 hours flapping its wings non stop. Looking for a favorable wind, it is able to fly even up to 6000 meters above in cold heights. If we count all the “sky walks” this bird makes during the year, that would be about 16.000 km (10.000 miles).
Arctic Tern (Sterna paradisaea)
Absolute recorders among bird migrants is the Arctic Tern. They nest near North Pole but that doesn’t stop them to later make a journey to the other side of the world, Antarctica… and back. This incredible bird round trip of around 70,900 km (44.000 miles), which is the longest regular migration by any animal on this planet. We can say this bird is almost always on its journey. The Arctic Tern, which lives more than 20 years in average, will travel around 2.4 million km during its lifetime.
Northern Fulmar (Fulmarus glacialis)
Each autumn the Northern Fulmar (Fulmarus glacialis), which lives in the north Atlantic, is ready to start about 12.800 km (8.000 miles) long journey to get to the small remote island Tristan da Cuhna located n the south Atlantic Ocean. The Northern Fulmar is about 50 cm long and has wingspan of up to one meter. It is able to flap its wings very fast for some time and then spends several hours gliding on stiff wings carried by air currents.
Arctic Warbler (Phylloscopus borealis
The Arctic Warbler nests in Alaska and when it comes to migration, the bird will have to fly its long way to get to southern south-east Asia where it will spend the winter.
Bar-Tailed Godwits (Limosa lapponica)
The bird that is known to have the longest non-stop flight of any bird migrant is Bar-tailed Godwits . It flies about 11,000 km from Alaska to New Zealand.
Ruby-throated Hummingbird (Archilochus colubris)
The small Ruby-throated Hummingbird (Archilochus colubris) that regularly nests in North America, every year flies across the Gulf of Mexico, passing the route of 800 km (500 miles) for about 20 hours. Some will say this is nothing compared to the route Blackcap or Arctic Tern pass when migrating, but you must consider the fact that this hummingbird weights only 3.5 g and is 7-9 cm long, and for such a small bird this is a real marathon. During the 20-hours-long flight this bird flaps its wings 50 times a second making no pause to rest.
Bird migrations, still not fully explained, have been the topic of study not only for scientists. Even Hesiod, Homer, Herodotus and Aristotle found bird migration interesting to study and made records of it. Aristotle knew many birds migrate in autumn and he believed they do so to escape from cold and hunger. But he was wrong about one thing – he thought that swallows don’t migrate and believed they spend the winter sleeping in their nests. But he wasn’t the only that thought so – the belief persisted until the 19th century.
Today we know the only bird that undergoes a form of hibernation is the Common Poorwill (Phalaenoptilus nuttallii). When winter comes, this nocturnal bird finds a comfortable cavity in the rock, reduces its body temperature from 41 to 15°C, almost stops to breathe… and waits for the spring to come.
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