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Pesticides endanger migratory birds

2019-09-13T17:16:35.685Z


Neonicotinoids are considered a danger to insects. But the plant protection product also harms migratory birds, confirms a study from Canada. The poisoning disturbs the travel rhythm of the animals.



In nature, timing is often crucial. This applies, for example, to the cycle of plants whose growth is subject to the seasons. This also applies to the migratory behavior of animals.

According to a new study, environmental toxins can have a negative impact on such rhythms. This has been shown by researchers using the example of migratory birds. The harmful substances are thus indirectly involved in the decline in stocks.

The agent imidacloprid from the class of neonicotinoids led to weight loss and longer resting time in badgers (Zonotrichia leucophrys), report researchers Margaret Eng from the University of Saskatchewan in Saskatoon (Canada) in the journal "Science".

Many synthetic pesticides kill on the field not only unwanted insects or pathogens, but also beneficial or at least harmless organisms to do so. Among the most well-known - and most controversial - remedies include the weed killer glyphosate and the so-called bee poison from the group of neonicotinoids.

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For the study, the biologists caught songbirds in the south of the Canadian province of Ontario. Numerous migratory birds rest there in the spring and eat a lot of food before they fly on to the breeding grounds in the north. Researchers administered a dose of imidacloprid equivalent to about ten percent of the lethal dose to the animals. Birds can absorb this quantity even in the open air in a short time.

The badger chambers then ate 70 percent less than the control animals and lost six percent of body mass within six hours, mainly fat stores.

In addition, the experimental animals flew later in comparison to the birds of the control group - on average after four days instead of half. The researchers predict that the birds will extend their stopover to recover from the poisoning.

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"Bird migration is a critical period for birds and the timing is important because delays can significantly affect their success in finding partners and nesting," says Christy Morrissey, senior author of the study. Ultimately, the means therefore have consequences on the breeding behavior. This explains in part why migratory bird species and farmland bird species decline so dramatically worldwide.

Bird protection expert Lars Lachmann of the German Nature Conservation Union (Nabu) considers the study to be very important, although imidacloprid has been banned in the EU in field application since April 2018. "The study gives indications of possible causes for the sharp decline in birds that are on and near agricultural land," he explains.

While in Germany the total stock of birds has remained essentially stable since 1980, the stock of farmland birds has decreased by 35 percent. Lachmann suggests studies on the plant protection product Thiacloprid, which is chemically closely related to Imidacloprid and is still permitted without conditions.

At the end of April 2018, the EU member states voted by a narrow majority for a further free-field ban of certain neonicotinoids - clothianidin, thiamethoxam and imidacloprid. According to experts, they can paralyze, kill or impair the ability to learn and orient themselves even at a low dosage.

Source: spiegel

All tech articles on 2019-09-13

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