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Alsace, air corridor and land of welcome

On the occasion of World Migratory Bird Day, which will take place on Saturday May 14, we take stock of these birds that come to Alsace, for a wingbeat or a season, with Cathy Zell, from the League for the Protection of Birds (LPO).

Cathy Zell is in charge of communication at the LPO, the League for the Protection of Birds, in Alsace. If she is not a specialist in migration, she knows enough to take stock of these birds of passage. We asked him three questions.

The question may seem silly (feathered) but the answer is rather complicated.

“Birds breed in a place that is suitable for their young, for their survival. This place must meet at least three criteria: climatic conditions, an environment rich in food and an ecological niche. In fact, birds compete for the most difficult territories. more favorable to reproduction, so over the millennia, some species have adapted to these empty ecological niches in order to survive.

When the season changes, the food goes down. The birds leave this place for another more favorable one. The environment (for the oriole for example), the length of the day (the swallows, April 15) trigger this migration.

There are therefore two types of migration.

– Prenuptial migration in spring (before breeding). The bird leaves its wintering area (Africa, Spain, southern France) and joins its breeding area, more or less distant (France, including Alsace, Northern or Eastern Europe). The migration front is quite wide even if some axes are well frequented (Rhine or Ill for terns and terns). In Alsace, in February-March, the first lapwings, Eurasian curlews, black kites, white storks, barn swallows, gray wagtails, woodlarks arrive. Common cuckoo, common nightingale, common tern, house and bank swallows, warblers arrive in April. In May, the various migrants arrived, with the honey buzzard being among the last to come.

Postnuptial migration (after reproduction) : The bird leaves its nesting area and reaches its wintering area, this is the “autumn migration” even if, for some birds, it begins in July (black kite, black swift). It lasts until October-November (thrushes, chaffinch, melodious linnet…). The migratory stopovers are often longer than in the spring. Migrants can be encountered almost everywhere, but privileged passageways are taken during this postnuptial journey. In Alsace, the Vosges passes and the Alsatian Jura are places where the postnuptial passage is concentrated.

The world champion of migration? The arctic tern which breeds in the Arctic and spends the winter in Antarctica.

“It’s very difficult to say: there are more than 10,000 species of birds in the world. Some, too far away to pass through Alsace, that’s for sure, but there are so many left! It’s difficult to make an inventory of the places. We know one thing is that there are never any absolute rules when it comes to living beings. One certainty: Alsace is an important migratory corridor. Mission Migration makes regular counts.

Alsace is already well located geographically speaking. In Northern and Western Europe, the migratory flow generally follows a North-East / South-West axis, Alsace, located on this trajectory, is one of the passageways for European migrants. Then, Alsace is a true air corridor by a phenomenon suction between the Vosges and the Black Forest favorable to air flows. Then there is also and above all water to drink. The Rhine of course, but also Plobsheim, the first major watering place for migrants from Scandinavian countries.

One can observe the various types of migrants.

The great travelers which go to winter in Africa, after having reproduced in Alsace or further north: swallows, black swifts, Eurasian curlews, nightingales, hoopoes, European oriole, hobereau falcons, black kites, red-backed shrikes. The water points are also a preferred migratory stopover for sandpipers and other birds that nest in northern Europe.

Partial migrants whose amplitude of movement is less and part of whose populations do not perform migratory movements (sedentary birds): chaffinch, thrushes, blackbird, house robin, European goldfinch, tits. As such, the Vosges passes are particularly crossed by East/West migrations such as the Markstein or the Alsatian Jura. Some birds simply flee the rigors of winter in the Vosges mountains, such as the bullfinches.

In winter, the Rhine Valley welcomes large numbers of water birds (ducks, geese, swans, loons, grebes) from northern areas where food has become inaccessible due to frost. These migrants are “wintering”. Each year, they are counted in January, during the Wetlands International count.

During the last decade, every winter, between 50,000 and 90,000 waterbirds have been counted in the Rhine Valley. These figures are down from those of the initial counts, where totals of 100,000 birds were regularly reached in January during the 1970s and 1980s.

“Global warming is disrupting migration, that’s for sure. The wintering areas are less and less far from the breeding areas since the temperatures are more and more mild. We see that a lot: reduced journeys except for certain very programmed like swallows who continue despite everything to cross the Sahara or Spain. The storks have adapted. They travel less distance when they do not simply stay put.”

“Light pollution is a very important risk factor. This is also the theme of this World Migratory Bird Day. The Anpcen has carried out studies on this. Artificial light is increasing by at least 2% per year worldwide and is known to have negative effects on many bird species. Light pollution is a serious threat to migratory birds, disorienting them during their night flights, causing collisions with buildings, disrupting their internal clocks or preventing them from undertaking long-distance migrations. In the United States, there have been millions of birds disoriented by light, spinning in circles and dying of exhaustion.

For example, did you know that the stork born in March goes off on its own to its wintering site? Without a parent, without a guide? Innately, she knows where she is going, in sub-Saharan Africa. And the same way back. These birds with “innate migration” orient themselves at the same time thanks to the stars, thanks to the magnetic field and to certain visual points. We understand better why our artificial lights can disturb them.

So if I had to conclude, I would say this: take care of migratory birds, they are precious. Do not destroy their nest, do not shoot game species. They have traveled thousands of miles to come to us, they are exhausted, they have weathered storms, escaped the clutches of their predators, welcome them. A cup of water, seeds … that they find at least their habitat.”

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