the giant pantry
MIGRATORY BIRDS IN THE WADDEN SEA TO TRAVEL IS TO LIVE
Especially during the spring and autumn, the great flocks of wading birds and geese create a stir . The Wadden Sea is Denmark’s National Park because the area is of crucial significance for the 12 - 15 million birds using the East Atlantic migration route, which covers an area, stretching south to north, of about 15,000 km, crosses more than 30 countries and therefore one of the world’s most important migration routes. Migratory birds as opposed to sedentary birds, breed in one place and overwinter in another. In the Wadden Sea, especially during the spring and autumn, the great flocks of wading birds and geese create a stir when they stop to rest here during their travels. The Wadden Sea is of immense importance as a resting, molting and foraging area for migrating birds. There are many good reasons why it is necessary to leave the pleasingly warmer skies and migrate, for example, to the arctic tundra in order to breed. Migratory birds seek areas with the greatest resources in terms of food. On the arctic tundra where space is vast, the distance to fellow species is quite large and this reduces the risks for spreading infectious diseases. In addition, the harsh winters in the breeding areas also help to reduce the numbers of birds-of prey and other predators. Finally, a trend shows that the sedentary birds in, for example, Africa tolerate the migratory birds outside their breeding season, but as soon as the sedentary birds show breeding behavior, they become intolerant towards the migratory birds and chase them away.
Experience migratory birds in .. SPRING
SUMMER
AUTUMN
WINTER
The bird’s weight ... before and after Species
Weight (g) Arrival
Departure
Icelandic Dunlin
100
230
Common Dunlin
42
86
Godwit
240
450
The Wadden Sea and the migratory birds
Some of the most valuable nature environments in the world are the tidal areas where the pulsating tide makes it possible for the sun to heat up the exposed seafloor at the low tide. Through the nutritionrich and often warm mud, the algae receive the extra energy that helps to create an enormous plant formation. The algae form the foundation for a gigantic production of other soil animals, such as mussels, worms, snails and crustaceans, which makes the Wadden Sea an immeasurable rich pantry for migrating birds on the East Atlantic route.
Klaus Melby, Vadehavscentret & Marco Brodde, Fiskeri- og Søfartsmuseet Translation: Nanna Mercer, Sirius Translation
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the giant pantry
The Oyter catcher breed in Northern Europe and migrate to Western Europe.
Intake and species Species
When
Number
Daily intake/bird
Daily intake/species
Icelandic Dunlin
Spring
440.000
1.000 cuckles
440 mio cuckles
Winter
500.000
300 cuckles
1.550 mio cuckles
Autumn
40.000
3.000 worms
120 mio worms
Oyster catcher Piet Avocet
Migrating birds and their fat depots
The energy intake in migrating birds is throughout their lives up to five times greater than what they actually need. The excess energy is used, among other things, for staying warm, for flying long distances, and for egg production. Birds are better at stocking energy in their fat depots than are mammals. This is an advantage since one gram of fat releases more than double the amount of energy compared to one gram of carbohydrate, while at the same time tying up twice as much water. Water is of great importance for migrating birds, especially when flying across deserts, oceans and mountain ranges. It is therefore important that migrating birds can build up their fat depots while they rest in the Wadden Sea. Many migrating birds do not manage, during the day, to collect enough food at the low tide to satisfy their needs, so they must also forage during the night.
Distance fliers
Migratory birds are either short, medium or long distance fliers, which can be noted from the shape of their body. Those birds that fly the longest all have a torpedo formed body. Among the short distance fliers, the mallard and the lapwing breed in Denmark, but migrate to the coasts in Germany and Holland, where they overwinter. The eider and the oyster catcher are medium distance fliers since they breed in Northern Europe and migrate to Western Europe. Finally, we have the absolute long distance fliers, which are the migrating birds such as the dunlin, the godwit and the turnstones that breed in the arctic but all migrate to the tropical Africa for the winter.
High and low fliers
The bird’s daily flights are made close to land, but when migratory birds are traveling, they rise to higher altitudes. Smaller birds such as the snow bunting
Klaus Melby, Vadehavscentret & Marco Brodde, Fiskeri- og Søfartsmuseet Translation: Nanna Mercer, Sirius Translation
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the giant pantry
The eider is unable to fly for up five weeks, while it changes is flight feathers. migrate at a height of about a kilometer, while the common sandpiper, the godwit and the lapwing can fly at heights of 4 - 6 kilometers. The larger birds, such as geese, cranes and storks can fly at heights of between 6 - 9 kilometers. To facilitate flying at such great heights, the birds must be able to utilize oxygen better than man, for example by bringing it along themselves. Birds have up to nine air sacks, but they can also stock oxygen in their hollow bones. In this way, the oxygen has a longer passage through the bird and can therefore be used optimally.
Molting and renewal
Migratory birds also use the Wadden Sea in other ways. In the spring and autumn, millions of used feathers can be found on the salt meadows, for feathers that have flown 4-7,000 kilometers are worn out and need to be renewed. Some birds use a different feather molting strategy; wading birds change their feathers continuously, while the eider is unable to fly for up five weeks, while it changes is flight feathers.
How do birds find their way?
ing. They simply have to follow along on the long trek without any induction training. The answer to how birds orient themselves during migration is far from clear, but the newest research show that an area in their brain contains neurons that can register magnetic fields, their strength and direction and thus, it is thought that birds can recalibrate their route if they go astray. How the birds orient themselves depend on several factors, since they also use the sun, the stars and, for landfall, their sense of smell.
See the giant flocks of birds
It is very difficult to truly comprehend 12 - 15 million migratory birds as a number, but the 40 different species of birds are spread across populations of over one million birds down to a few hundred individuals. Giant flocks of birds glistening in the sun are not an unusual sight in the Wadden Sea. To see and experience this, you may want to participate in the nature guide’s different tours available from March to May and again from August to October, while the geese can also be seen during the winter. The trend seems to be that the migrating birds come a little earlier and stay a little longer.
Migratory birds have an inborn ability to find their way, which is seen when their young are left to their own devices on the second or third day after hatch-
Klaus Melby, Vadehavscentret & Marco Brodde, Fiskeri- og Søfartsmuseet Translation: Nanna Mercer, Sirius Translation
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the giant pantry
Things to do ...
Learn about migratory birds here ...
Bird trips on your own. Visit the nature centers for guidance.
NaturKulturVarde Gl. Skovfogedbolig Roustvej 111 DK-6800 Varde T: +45 75 22 22 50 E: nkv@naturkulturvarde.dk W: www.naturkulturvarde.dk The Fisheries and Maritime Museum Tarphagevej 2-6 DK-6710 Esbjerg V. T: +45 76 12 20 00 E: fimus@fimus.dk W: www.fimus.dk Vadehavscentret Okholmvej 5 Vester Vedsted DK-6760 Ribe T: +45 75 44 61 61 E: info@vadehavscentret.dk W: www.vadehavscentret.dk Naturcentret Tønnisgård Havnebyvej 30 DK-6792 Rømø T: +45 74 75 52 57 E: info@tonnisgaard.dk W: www.tonnisgaard.dk
tips for further reading
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Life on the Waddens The seals in the Wadden Sea The oysters in the Wadden Sea Black Sun
About Vadehavets Formidlerforum... Vadehavets Formidlerforum is a partnership of visitor centers that mediate the Wadden Sea’s natural and cultural heritage. VFF’s main activity is to coordinate projects that highlight the nature and culture heritage of the Wadden Sea.. Learn more at www.vadehav.dk
Klaus Melby, Vadehavscentret & Marco Brodde, Fiskeri- og Søfartsmuseet Translation: Nanna Mercer, Sirius Translation
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