More and more storks are overwintering in Switzerland

Storks are no longer drawn to Africa in winter. They are staying in Switzerland and Spain. This is having a positive effect on reproduction. Within a single year, the number of breeding pairs in Switzerland has risen by 18 percent, and over 1,000 young birds have been counted.

In January 2020, 669 breeding pairs were counted in Switzerland, explains Peter Enggist, director of Storch Schweiz, when asked. A year earlier, the figure had been just 566. He confirmed a report by the «Tages-Anzeiger» stating that more storks had bred in the canton of Zurich this summer than in years.

Seventy years ago, the stork had been extinct in Switzerland, said Enggist. In the 1960s, the reintroduction of young storks began in Altreu SO. Over the past ten years, the stork population in Switzerland has grown by ten percent annually.

According to Enggist, the reason for this is that virtually no storks from the western population overwinter in Africa anymore. They overwinter at landfill sites in Switzerland and Spain. The cause, however, is not climate change, but the abundant food supply at the landfills. In the Sahel zone, storks risk starvation or being hunted.

Last winter, 600 storks remained in Switzerland. In spring, these birds secured the best nesting sites and subsequently also raised the most offspring. To study the behaviour of the storks, more than 60 birds have been fitted with transmitters.

Three scenarios

Landfills containing organic materials are increasingly being closed, Enggist explains. There are three possible scenarios for how the birds might respond. According to the stork specialist, the ideal outcome would be for the birds to migrate back to Africa. However, it is also possible that the storks would remain in their breeding areas more, or that they would starve in Spain.

The birds of the eastern population, on the other hand, continue to overwinter in Africa, as Enggist notes. Their numbers are also declining steadily, because farming in Eastern Europe is becoming ever more intensive and storks are being heavily hunted in North Africa.

In Switzerland, in addition to the stork colony at Altreu, there are particularly large numbers of storks in the Murimoos area in the canton of Aargau, at the Avenches stud farm, and in Uznach SG. Storks have never been present in the mountain regions, in Valais, Graubünden, or Ticino.