Birds: Collateral Victims of Agricultural Intensification in Europe
For half a century, the scientific community has been sounding the alarm about the effects of pesticide use on human health and the disappearance of numerous species in agricultural environments. Rachel Carson’s pioneering work warned as early as 1962 of “silent springs” caused by the decline of birds, collateral victims of pesticides due to environmental poisoning and the disappearance of insects.
Vincent Devictor, University of Montpellier and Stanislas Rigal, ENS Lyon
At the heart of the issue is an agricultural model that relies on ever-increasing industrialization to remain competitive on the international stage, making heavy use of pesticides. This model is becoming increasingly dominant in France, where the number of farms is steadily declining (down 40% since 2000) and their size is growing (their average size has quadrupled since the 1960s).
As a result, the amount of farmland used by farms that rely heavily on pesticides and fertilizers has continued to grow. In fact, only 17% of Europe’s soil is free of pesticide contamination. Since 2009, more than 300,000 hectares of farmland—often fertile land— have been paved over.
Beyond these alarming observations and prophecies, is there tangible and unequivocal scientific evidence that this model of agricultural production poses a threat to living organisms on a European scale?
The challenge of conducting experiments on living organisms under real-world conditions
At first glance, experimentation seems like an ideal approach. For example, feed sparrows seeds coated in pesticides, and they’ll be in poorer health. Fair enough. The approach is likely to work.
But outside the laboratory, where variables are no longer directly controllable by the researcher, we enter a complex world where processes are driven by multiple intertwined factors. Under these conditions, how can we establish evidence of the effect of a particular factor on health or the environment?
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To overcome this challenge, the scientific method can always rely on protocols and control variables. Thus, the effect of substances suspected of being problematic and of all other factors with a potential impact will not be manipulated experimentally, but studied statistically.
For while it is already somewhat cruel to force-feed pesticides to birds, it is even more absurd to imagine that we can test everything. Instead, we can examine whether the use of increasing amounts of pesticides leads, over time, to a decline in insect populations. In other words, we will approach the issue from an epidemiological perspective.
There is, however, a catch. One could always argue that it is not pesticides that are to blame, but rather stress, air pollution, drought, or any other factor that might directly or indirectly influence the system under study.
We therefore needed to find a way to gain a clearer understanding of the situation. That is exactly what we did, working with a team of 50 researchers in an open-access study published in May 2023. Our goal was to determine whether one pressure factor outweighed the others—and if so, which one—to explain the decline in the populations of many bird species across Europe.
The unprecedented scale of the devastation in the agricultural sector
The first step was to quantify this decline. Thanks to the dedicated work of numerous volunteer ornithologists who followed the same monitoring protocol every year across 28 European countries, an exceptional dataset was compiled, covering the period from 1980 to 2016. This was a crucial step: starting with the birds themselves in their natural habitats, rather than relying solely on experiments involving a few isolated individuals in a laboratory.
The study tracked 170 different species, including wild populations that are directly affected by pollution, climate change, hunting practices, human disturbance, and the risk of predation.
Far from limiting ourselves to agricultural areas, we took a close look at all types of habitats: forests, cities, mountains, open and closed areas, cultivated and uncultivated lands… In short, we set out to assess the health of Europe’s birds, without holding back.
The result? Bird populations in Europe declined by a quarter between 1980 and 2016—a loss of 800 million birds over that period, or an average of 20 million per year. A massive decline, yet not surprising: birds have had to adapt to the profound changes in landscapes and lifestyles that occurred during the20thcentury.
Not all bird species are affected in the same way.
- For example, bird populations living in forest habitats have declined by 18%;
- Those in urban areas, 25%,
- What is surprising, however, is the dramatic decline in the number of birds in agricultural plains: their population has plummeted by 57%!
An unenviable record: it is one of the most dramatic declines ever recorded on this scale for living organisms.
Demonstrating the link between agricultural intensification and bird decline
We needed to dig deeper to understand what was causing this decline. Fortunately, we had the perfect data to test whether climate, habitat changes, and industrial agriculture could be held responsible.
Let’s imagine for a moment: at a specific location—say, at the edge of a rapeseed field—one or more ornithologists have counted the number of birds each year using the same method. And, specifically for this year and this location, we also have data available on the expansion of intensively farmed areas, changes in temperatures, the spread of urbanized land, and variations in forest cover.
It is this process—repeated at thousands of sites across the 28 countries studied over several decades—that has made it possible to build the most comprehensive and accurate database of wildlife monitoring data ever collected in Europe.
This allowed us to establish a statistical link between bird populations and these various pressures, and to arrive at a second key finding: species decline coincides with the increasing intensification of agricultural practices. In environments where industrial agriculture is more prevalent—regardless of climate and other conditions—bird populations are declining more rapidly.
We were, however, aware of another potential pitfall: that this link might simply be a coincidence attributable to chance. Yet that is not the case. Our analyses show that we are no longer dealing with mere correlation, but with an unequivocal link.
One final finding has allowed us to add another piece to our understanding of the situation: species that primarily feedon insects—which have been eradicated by pesticides—are even more severely affected than other species.
Global warming and land development are also factors
Of course, the intensification of agricultural practices is not the only factor behind the observed declines. Climate change—particularly rising temperatures—is a second major contributing factor.
- Northern species, which are adapted to cold environments (such as the Boreal Tit, whose population has declined by 79%), are moving northward and seeing their populations decline sharply as temperatures rise.
- Conversely, other species adapted to warm environments (such as the Sardinian Warbler, whose population is growing) may benefit from this.
The spread of urbanized areas also comes at the expense of birds, which are unable to live in mineral-rich and polluted environments and whose habitats are becoming fragmented.
Even species capable of nesting in urban areas are in decline (such as the common swift, whose populations have fallen by 17%), largely due to the lack of available nesting sites on modern buildings and the low abundance of insects in these environments.
Finally, the recent recovery of forest cover in Europe—which is often the result of plantations—is not enough to halt the decline of species that depend on natural forests.
Sow doubt… and buy some time?
These findings should encourage us to drastically reduce our use of pesticides. But for advocates of agrochemicals, the scientific evidence is never strong enough.
A situation reminiscent of those involvingasbestos and tobacco, or even the efforts by fossil fuel producers to delay public awareness of climate change.
All of these industries have exploited the inherent difficulty of establishing scientific proof in order to buy time, perpetuate doubt, and preserve both their reputation and their profits. Maintaining doubt has thus become a strategic move.
To the point that manufacturers have now established themselves as a scientific authority among regulatory agencies, particularly in Europe.
It has become irresponsible to downplay the impact of industrial agriculture and its pesticides, and to hide behind alleged biases, a lack of perspective, or the supposed absence of alternatives— which, in fact, do exist.
The widespread use of pesticides carries a significant social and economic cost, which, however, is not reflected in prices as long as their use continues to be encouraged and subsidized. In terms of human health, their effects are increasingly well documented.
Everything points to the need to change this production model. How can we be content to label as “conventional” a form of agriculture that is incompatible with maintaining the health of both humans and non-humans?
The necessary changes cannot rely solely on the goodwill of farmers who are caught up in an industrial model designed by and for the agribusiness sector and embedded in an export model driven by speculation or the pursuit of the lowest possible price.
What is needed are transformative changes in the way we live in the world, produce, and consume. Policy tools should serve as levers capable of initiating this transformation, rather than clinging “at all costs” to a model that has run its course.
It is urgent that decision-makers at the European, national, and local levels finally face up to the devastation caused by certain outdated chemical farming practices that destroy life, trap farmers, and make a mockery of consumers.
Science and society are mutually reinforcing and benefit from engaging with one another. Research can draw on citizen participation, improve people’s daily lives, or inform public policy. This is demonstrated by the articles in our series “Science and Society: A New Dialogue,” published with the support of the Ministry of Higher Education and Research.
Vincent Devictor, Research Director in Ecology, University of Montpellier and Stanislas Rigal, Postdoctoral Researcher in Conservation Biology, ENS Lyon
This article is republished from The Conversation under a Creative Commons license. Readthe original article.