Heavy rain causes swallow deaths – Knowledge

This week, 120 completely exhausted, partly half-dead swallows were handed over to Ferdinand Baer, ​​the head of the wild bird rescue center in Regenstauf. He and his team from the LBV nature conservation association are currently trying to nurse the animals back to health. The small birds are warmed, dried if necessary and given food and water. “Many died anyway,” says Baer. “I’ve never seen anything like it.”

What happened? The heavy rain at the weekend and at the beginning of the week has taken a heavy toll on the small migratory birds. “We have received many pictures of swallows lying dead on the ground,” says Angelika Nelson, ornithologist at the LBV. Other pictures show swallows crowded together, hungry and freezing, on window sills or hanging under roof overhangs. “The situation is dramatic,” says LBV chairman Norbert Schäffer. “The affected birds that we know about are just the tip of the iceberg.” It is not possible to say how many swallows have actually died because of the extreme weather. “And in Austria it is much worse.” Thousands of dead swallows have been found there.

“The extreme weather caught the animals in the middle of their migration,” explains Baer. The ornithologist assumes that many of the dead animals came from countries in northeastern Europe, such as Poland or Finland. “Many had probably already traveled several hundred kilometers and were therefore weakened anyway.” Then they flew into the weather trap.

Migratory birds are usually able to cope with bad weather fairly well. “They often manage to fly around the bad weather area,” says Nelson. Or they take a break and wait until conditions are better. Both were impossible this time. The storm came so quickly and was so extensive that the birds had no chance to escape.

Swallows can only eat while flying

In addition, swallows firstly feed exclusively on insects and secondly they only catch them in flight. During the heavy rain, however, neither the insects nor the swallows could fly. “Other bird species such as garden warblers can hide in the bushes when it rains and look for insects on the ground or on the leaves,” says Schäffer. Still others resort to berries, which species such as flycatchers and common redstarts do in the autumn anyway because berries are richer in calories than insects and the animals need to eat to store up winter supplies. The swallows cannot do any of this; some simply starved to death. For others, the cold did the rest. “Birds are warm-blooded animals,” says Nelson. “They have to maintain a constant body temperature even in wind and rain, and that costs energy.”

There are two species of swallow in Germany: house martins and barn swallows. Almost all of the dead animals were house martins. “Of the 120 birds that were brought to Regenstauf, only five were barn swallows,” says Baer. Baer suspects that the reason for this is the different flight times of the two species: the storm caught the house martins in the middle of their migration. Barn swallows usually start migrating later and therefore probably did not get caught in the heavy rain. The swifts were also lucky: they are also migratory birds and, like swallows, they only eat insects that they catch in flight. But the swifts fly off earlier. They had already passed through when the storm began.

It is unclear whether and how the death of the house martins will affect the population as a whole. “Birds can usually cope with such events and compensate for the losses,” says Baer. But the current event was extreme. And house martins are not threatened with extinction, “but the population is shrinking,” says Schäffer. The reason for this is many other stress factors that the birds have been struggling with for some time: the death of insects, but also a lack of nesting opportunities because there are fewer and fewer niches on buildings in which the animals can build their nests.

The storm has now caused a so-called train jam. Animals that would normally be in southern France or Spain on their way to Africa are still stuck in Germany. “Some are still so exhausted that they cannot fly any further,” says Schäffer. Should we leave the animals to their fate and hope that – as the weather gets warmer again – they will recover, fly further and arrive at their winter quarters a little late? Should we keep them in aviaries over the winter? There is even talk of flying the exhausted swallows after their fellow swallows by plane. There is a precedent for this: in the autumn of 1974, birds were unable to continue their journey south due to weeks of rain in the Alps. Hundreds of thousands of animals died. The survivors eventually flew south by plane.

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