Neonicotinoids, a class of insecticides introduced in the 1990s, were widely used in agriculture for decades until they were banned in the EU in 2018 due to their harmful effects on biodiversity, particularly bees and other pollinators.

Encouraging findings

A study published last November in the scientific journal Environmental Pollution suggests that this ban has had a positive impact on insect-eating bird species such as the blackbird and the blackcap. It is the first study to examine specifically the link between neonicotinoids and bird populations since the 2018 ban.

The research was conducted by French scientist Thomas Perrot, who works for the Foundation for Research on Biodiversity. His findings are based on data collected between 2013 and 2022 from more than 1,900 farming plots, covering 57 bird species.

The study shows that on plots where neonicotinoids stopped being used, populations of insect-eating birds increased. More specifically, between 2013 and 2018, before the ban, populations of these birds were declining by around 13%. Between 2019 and 2022, after the ban, this decline slowed to about 9%. In other words, bird populations are still declining, but at a slower rate.

According to Perrot, this tells us two things: “First, that the effects of this molecule are persistent, which may be explained by its persistence in the environment or by the fact that bird or insect populations need more time to recover, since the study was only four years after the ban. And the second thing is that there has nevertheless been a slight recovery, of around 2 or 3 %.”

Teamwork between scientists and ornithologists

Perrot was able to reach these conclusions thanks to long-term monitoring by ornithologists. They carry out standardized bird counts that provide detailed data on bird populations in France.

Grégoire Loïs is one of them. One early morning in April, we met up with him in the Rambouillet forest, in the Paris region, to carry out a bird count. He showed us how it all works: “The points are marked out in advance on a map based on habitat and accessibility. Then, I arrive at the point on a specific date, the same date every year, three times in the spring. And for five minutes, I note down everything I hear, and potentially what I see.”

For Loïs, knowing that his data will be used in scientific studies like Thomas Perrot’s is a real motivator. “Seeing that there are people who are taking things much further, who are trying to identify the factors driving species population changes, and in Thomas’s case, pesticides, is really one of the main reasons I participate,” he explains.

The need to go further

For Perrot, the results are a sign that strict environmental regulations can have a tangible positive impact on biodiversity. However, he warns that the neonicotinoid ban alone will not be enough to halt the decline of bird populations.

“There are still quite a few other insecticides that can have an impact on these populations and should be banned,” he explains.

But that’s still not enough: “We therefore need to establish an agricultural system that allows farmers to do without these pesticides.” Perrot advocates for “a system that pays farmers better.” “I believe that once farmers are paid better, the transition to low-input systems, in terms of both pesticides and fertilisers, will be possible,” he says.

We also need to rethink the way farmland is structured, Perrot adds. “In certain areas, we also need to reintroduce semi-natural features, such as hedgerows and woodlands, to support this biodiversity.”

Why does Perrot consider this paradigm shift to be so important? Because birds play a crucial role in our ecosystems. “There are several reasons why birds are important. One could start by looking at the financial benefits for farmers. They are excellent pest controllers. But for many people, they are a source of wonder. And ultimately, they also say something about the overall health of the environment. They are heavily dependent on the resources below them – insects and seeds. And a decline in those populations generally indicates that the environment is in a rather poor state.”

And so, the study raises a broader question for policymakers and citizens alike: is the EU doing enough to restore biodiversity, or are much more ambitious measures needed in the years ahead?

Justine Hagard & Thaïs Chaigne