Right at the entrance to the village, a sign warns: "Attention! Storks flying low!" This is meant a bit jokingly with a view to the tourists who come to the village of Uehlfeld because of the many storks. But just a few meters further on, you can see that the warning is no coincidence. Everywhere on the roofs the white storks rattle. On the church tower alone, they built five nests. Again and again, one of the white and black birds sails majestically from roof ridge to roof ridge - and across the main road that runs through the middle of the village.
"We have 53 nests at the moment," says Detlef Genz, mayor of the community of around 3000,25 inhabitants in northern Bavaria. "As far as I know, more than in any other place in Germany." However, this cannot be said with certainty. But there are already a lot of them, says stork expert Kai-Michael Thomsen from the Michael Otto Institute of the Nature and Biodiversity Conservation Union Germany (Nabu) in Bergenhusen. The community in Schleswig-Holstein has a larger colony of 730 nests, but has just under <> inhabitants.
Nationwide, around thousands of pairs breed
Once upon a time, the white stork was almost extinct in Germany. According to Thomsen, there are now around 10,000 pairs of storks breeding nationwide. In recent years, the population in western Germany has increased sharply, says Thomsen. The states with the most storks are Baden-Württemberg and Lower Saxony. In the east, on the other hand, stocks are stable at best, and in Mecklenburg-Western Pomerania they are even declining. And this development has consequences: "If there is great population pressure, colonies can emerge in favorable locations."
Just like in Uehlfeld. Gerhard Bärtlein, 74 years old, grew up with the storks. He can still remember times when there was no stork to be seen. But for years there have been more and more of them – also on his property. Five pairs of storks are currently breeding on its roofs. It would probably have been much more if he had not prevented nest building in unsuitable places at an early stage. "Maybe word has got around in the stork world that Uehlfeld is a good place to live?" he speculates.
Colony formation instead of aggression
Scientifically, the behavior of storks is difficult to study, so experts can only make assumptions. "It's a crazy thing," says Wolfgang Fiedler from the Max Planck Institute of Animal Behavior in Radolfzell on Lake Constance. In the first few years, a breeding pair will try everything to defend its territory. "But when a certain density is reached, it's like pulling a lever. But what exactly happens between aggression and colony formation is not entirely clear." Similar behaviour has been observed in mute swans on the Thames in London.
According to Fiedler, the increasing colony formation in storks could also be related to the changed migratory behavior. The number of storks flying to their winter quarters via the western route has increased. About two-thirds of them no longer fly as far as Africa, but spend the winter mostly in Spain, where sufficient food can be found in landfills. These storks therefore have a much better chance of survival than the eastern migrants, who travelled many thousands of kilometres more – in some cases as far as South Africa.
"Since the number of westward migrants has been increasing, it has been teeming with stork villages," says Fiedler. Especially in the south and southwest of Germany, villages with more than ten pairs of storks are no longer a rarity. And that could have an impact on the return of storks to Germany, he suspects. The western migrants, who would have to travel a shorter distance, could sit on the nest as early as mid-February. "As the density increases, there is greater pressure to return sooner. Whoever sits on the nest first always has advantages."
"It's enough now"
Tourism has been boosted by the storks in Uehlfeld: excursionists and amateur ornithologists are enthusiastic, but some residents are less so. Even Gerhard Bärtlein, who has a big heart for storks, as he says himself, says: "It's enough now." After all, once the birds have decided on a location, it is not so easy to dissuade them. This is particularly problematic if they build nests on heated fireplaces or on the top edges of solar systems, says biologist Oda Wieding from the State Association for Bird and Nature Conservation in Bavaria.
Three years ago, for example, storks paralyzed the small brewery of the Zwanzger brewery inn in Uehlfeld because they were breeding on its chimney. Another time, the inn's chimney was blocked, says boss Susanne Zwanzger – and she turned off the heating in March and the guests had to freeze.
In Dinkelsbühl, about 100 kilometers away, storks even triggered a fire brigade operation last year: According to the city, the trigger did not work in a museum because of a stork's nest on the chimney and the carbon monoxide load increased. The fire brigade then removed some nests in the old town for safety reasons.
Such problems will have to be dealt with more intensively in the future, predicts Nabu expert Thomsen. In Uehlfeld, they have by and large come to terms with the storks, says Mayor Genz. "A lot of people – and I think most of them – enjoy the sight of storks again and again." In addition, the colony cannot continue to grow, he says. "It's a natural way to do that." Thomsen also confirms this: "At some point, the competition is so great that there are more fights and the storks throw each other's eggs out of the nest, or the stress in the colony means that the breeding success is not so great."