Although summer is far from over, migratory birds have already begun their long journey to Africa. One of their favourite stopovers is the ‘Schlammwiss’ wetlands in Munsbach, a protected nature reserve where staff monitor and support the flocks in order to strengthen bird conservation.
As the sun set, Jim Schmitz, Vice-President of the nature protection association natur&ëmwelt, described how swarms of swallows were gathering across the reed beds to rest before continuing their journey south. He stressed that the reserve functions as a kind of service station for migratory birds, which from mid-August into September can find there everything they need: food, shelter, and calm surroundings. In his words, the stopover is essential for their survival.
Schmitz went on to explain that ringing work is central to monitoring efforts. Each swallow caught in the reserve is fitted with a small numbered ring produced in Belgium by the Royal Institute of Natural Sciences.
This, he noted, works like an identity card: if the bird is recaptured, researchers can track where it came from. Mortality rates for small species during migration, he said, are extremely high, ranging between 75% and 80%, particularly when crossing the Sahara, a 3,000km stretch with no food or water.
Data collected since 1969 has shown clear migration routes: the birds fly south over France and Spain, cross at Gibraltar, where the sea narrows to just 19km, and continue into Africa, Schmitz explained.
According to Schmitz, the swallows ringed in the ‘Schlammwiss’ are frequently later recorded in reserves in Niger and Congo, where some 15 to 20 million birds overwinter each year. Long-term ringing data has revealed valuable insights into age, mortality, and flight paths, allowing conservation measures to be better tailored, he said. Some swallows returning to the reserve have been recorded at seven to nine years old, which he described as unusually old for such a species. Other bird types, he added, can reach twelve or even thirteen years.
He also pointed out that three swallow species dominate the reserve: the sand martin, the house martin, and the bank swallow. The sand martin, in particular, is known for returning year after year to the exact same nesting spot. This, Schmitz said, underlined just how vital it is to protect and maintain habitats in the long term.
Schmitz further noted that the site is managed by the Foundation Hëllef fir d’Natur, which deliberately buys and preserves such biotopes. While they are often of little agricultural value, they are extremely important for biodiversity, he said. He explained further that local farmers also benefit: the land can provide extra harvests in dry years, and they receive biodiversity payments in return.
He concluded that agriculture and conservation can work hand in hand. To highlight the importance of the swallow, the reserve even hosts an annual “Swallow Day”, held this year on 21 and 22 August.
