Farming News - Neonicotinoids linked to bird decline

Neonicotinoids linked to bird decline

 

New research from scientists in the Netherlands has suggested neonicotinoid pesticides may play a part in bird population decline. The study, published in Nature this week, adds more scientific weight to the case against the pesticides, which were partially banned in Europe last year in light of evidence of their impacts on bees.

 

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Late last month, the expert task force on systemic insecticides warned that the products, the most widely used of which are the neonicotinoids, are bad for life at every level of the ecosystem. Publishing the conclusions of their four year review, the IUCN-convened task force warned that the chemicals are already causing significant damage to a wide range of beneficial invertebrate species, but also that their use may be threatening animals higher up the food chain, including birds. They found evidence that the products also risk harming species of bird and fish at levels found in the environment.

 

The Dutch researchers, from Radboud University, Nijmegen, found a correlational link between use of neonicotinoid insecticide imidacloprid – one of three substances 'partially banned' by the EU in December – and declining populations of 15 species of insectivorous bird. They found that insect-eating birds such as starlings and swallows are declining more rapidly in areas where concentrations of the pesticide in surface waters are highest.

 

Imidacloprid is the most widely used insecticide in agricultural systems around the world. This is the first research to show a link between its use and possible harmful effects for vertebrates. Neonicotinoids were introduced to the Netherlands in the mid-1990s and although bird populations were in decline before their introduction, local variations in losses were not noticeable until after their widespread use, researchers said.

 

Professor Hans de Kroon, who oversaw the study, said indirect impacts on birds via the food chain explains their decline better than other factors, such as land use change or pollution.

 

"The decline in farmland bird species started before 1995, but the local differences in this decline that we have established after the introduction of imidacloprid are not seen in the counts made before that time," said Ruud Foppen of Sovon Centre for Field Ornithology.

 

Although they said that a causal link is likely between neonicotinoid use and effects felt by local bird populations, the researchers do not yet know precisely what is causing the decline; it could be a lack of food for the birds, the effects of eating contaminated insects or a combination of several different factors. For some species, eating seeds with a neonicotinoid seed-dressing could also play a part.

 

The scientists said "It is not clear whether breeding success is declining or mortality is increasing, or both." De Kroon added, "Neonicotinoids were always regarded as selective toxins. But our results suggest that they may affect the entire ecosystem."

 

Radboud also released a video outlining the study's findings: