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🇩🇪 Germany /Environment & Climate

Berlin’s sparrow population has plunged by 70% since 2021

From Der Spiegel · () German

Translated from German and summarized by DistantNews. Read the original for the full story.

At a glance

In-depth Named sources Under investigation
  • Berlin’s house sparrow population has fallen by about 70% since 2021, according to biologist Jörg Böhner and counts by Nabu Berlin.
  • Experts are considering causes including disease, pollution and climate-related increases in parasites and mosquitoes, but no explanation has been confirmed.
  • Berlin had long been considered Germany’s sparrow capital because its comparatively unmanicured environment provided food and nesting sites.

Berlin’s house sparrows have declined so sharply that many suitable nesting sites now stand empty. Biologist Jörg Böhner says the city’s population is around 70% lower than it was in 2021.

Nabu Berlin reached a similar conclusion through its annual “Hour of Garden Birds” count, describing the trend as a “free fall.” The organization says the most troubling aspect is that the cause remains unknown.

It is around 70 percent lower than it was in 2021.

· Jörg BöhnerThe Berlin biologist describes the decline in the city’s house sparrow population.

The decline extends beyond Berlin. House sparrows, once considered among the world’s most numerous wild birds, have fallen sharply in many large cities. Evolutionary biologist Glenn-Peter Sætre writes that the species has almost disappeared from the centers of cities such as London and Amsterdam. Norway added the house sparrow to its Red List of threatened species in 2021.

And the terrible thing is: We still do not know what the cause is.

· Nabu BerlinThe conservation group comments on the unexplained collapse in sparrow numbers.

Berlin had long stood apart. Unlike cities such as Hamburg and Cologne, its sparrow numbers had not previously declined. Böhner attributes that partly to the city being “less sterile”: green spaces are mowed less often, and edible waste can often be found. “The messier, the better for the sparrow,” he says.

Böhner suspects that a disease may have sharply reduced the population. One possibility is avian malaria, caused by Plasmodium parasites transmitted by mosquitoes. Higher temperatures help both the parasites and their carriers develop more quickly, he says, making climate change a factor that may support their spread. Avian malaria does not threaten people.

The messier, the better for the sparrow.

· Jörg BöhnerBöhner explains why Berlin’s less manicured urban environment had previously suited sparrows.

A study of London sparrows found that about 74% of birds in declining populations carried Plasmodium relictum, and that heavily infected birds had lower winter survival rates. The parasites usually do not kill birds directly, Böhner says, but they can reduce their fitness. No comparable analysis has yet been conducted in Berlin, although one is being considered.

The parasites usually do not kill the birds directly, but they can reduce their fitness.

· Jörg BöhnerHe explains how avian-malaria parasites could affect sparrow survival.
About this summary

Originally published by Der Spiegel in German. Translated, summarized, and contextualized automatically by DistantNews, with a note on how the source frames the story. Not individually reviewed before publishing. How this works.

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