Impact of pesticide use on avian populations in French vineyards: an integrative approach – VITIBIRD

This project relies on several unique methodological infrastructures and approaches—including a national sampling design, long-term historical monitoring of bird populations, the BACCHUS experimental field site, chemical and biological analysis laboratories, and experimental facilities—which form the backbone of the VITIBIRD project.

Analytical facilities at the University of Bordeaux made it possible to assess the level of contamination by multiple pesticides in vertebrates living in vineyards, using innovative techniques adapted to the samples collected.

Historical monitoring programmes of common bird populations conducted by the French National Museum of Natural History (MNHN) have enabled us to describe changes in avian biodiversity and the status of bird populations in vineyard landscapes over the past 30 years. In parallel, the network of volunteer bird ringers provided contamination data for birds from more than 30 vineyard and non-vineyard sites.

CNRS analytical tools and experimental facilities made it possible to test the causal relationships identified in the field and to investigate in greater detail the effects of key pesticides on birds’ physiological functioning and performance.

The BACCHUS experimental landscape facility (INRAE) enabled us to jointly assess, under natural conditions, the effects of agricultural practices (organic vs. conventional) and landscape complexity on birds’ contamination levels and health status. This experimental site also provided an opportunity to investigate how agricultural practices and vineyard landscape structure influence the ecosystem services provided by birds, particularly their contribution to the control of grapevine pests.

VITIBIRD showed that vineyards are environments particularly exposed to pesticides. Birds living in vineyards are contaminated by mixtures of several substances, with substantially higher levels than those found in forests or cereal-growing areas. The research highlighted particularly high levels of triazole fungicides, as well as substantial copper contamination. Vineyards therefore appear to be environments strongly affected by chemical contamination.

At the national scale, our results show that the greater the use of pesticides, the lower bird abundance is in agricultural landscapes. However, these effects vary according to crop types and agricultural practices. In wine-growing areas, a higher proportion of land devoted to vineyards is associated with lower avian biodiversity, whereas the presence of forests, grasslands and other natural landscape features promotes bird diversity.

VITIBIRD also showed that pesticides can have substantial effects on birds even when exposure levels do not cause immediate mortality. Experiments with tebuconazole, a fungicide widely used in vineyards, revealed disruptions of metabolism, endocrine functions and immune defences. Exposure can also affect embryo development and juvenile survival. It may further increase birds’ susceptibility to certain diseases, such as avian malaria, with potential impacts on their survival.

Finally, the project showed that birds play a role in vineyard functioning. Great tits, for example, consume insects that can damage grapevines and may therefore contribute to the natural control of pests. However, they also consume organisms that are themselves predators of these pests. The effects of birds on biological control are therefore complex and depend on interactions among different species.

Overall, VITIBIRD showed that pesticides, agricultural practices and landscape structure concomitantly influence biodiversity and vineyard functioning. Maintaining forests, grasslands and other natural landscape features therefore appears to be an important lever for promoting biodiversity and ecological functions in vineyard landscapes.

The results of VITIBIRD open up new perspectives for improving our understanding of, and reducing, the impacts of viticulture on biodiversity and ecosystem functioning.

A first step will be to broaden the range of contaminants to which birds and other organisms are exposed. Beyond the pesticides already studied, it will be important to consider other substances such as glyphosate, PFAS, TFA and copper, and to monitor their presence across a larger number of vineyards. We also need to better understand how animals are exposed to these substances and under which circumstances multiple contaminants occur simultaneously.

This approach will provide a more realistic picture of exposure in vineyards, where animals are rarely exposed to a single compound. Future research will therefore investigate how multiple contaminants interact, as some may amplify or, conversely, reduce each other’s effects. It will also help explain why some species are more sensitive than others and how the consequences of exposure may vary across life stages.

Another important perspective will be to expand the spatial scale by comparing different vineyards and regions. This will help disentangle the effects of climate, agricultural practices and landscape structure on biodiversity. A key objective will be to identify landscape characteristics and agricultural practices that can maintain diverse bird populations while limiting their exposure to contaminants.

Future research should also better quantify the benefits provided by biodiversity to vineyards. This will include determining the extent to which birds and other organisms contribute to the natural control of pests, as well as investigating other important ecosystem functions such as pollination. These benefits can then be considered alongside the economic costs and benefits of different agricultural practices, in order to identify solutions that support biodiversity while remaining compatible with wine production.

Finally, VITIBIRD could be expanded towards a One Health approach, considering the health of ecosystems, animals and, more broadly, the environment in which human populations live. Studying other groups of animals, such as bats, amphibians and fish, will help improve our understanding of how contaminants move through ecosystems.

Ultimately, this research should contribute to the development of vineyard management strategies that reconcile reduced contamination, biodiversity conservation, the maintenance of ecosystem services and the economic sustainability of viticulture.

Le projet, débuté en 2021, a d’ores et déjà permis au travers de 4 publications de démontrer la (1) contamination des oiseaux par les fongicides dans les paysages viticoles, (2) les effets sublétaux de cette contamination pour les oiseaux considérés, (3) l’impact des pratiques viticoles sur la biodiversité aviaire.

The impact of pesticides on biodiversity and health is widely debated, particularly in wine-growing agro-ecosystems where pesticides are massively used. It is precisely the impacts of the main pesticides used in vineyards (fungicides, insecticides, herbicides) on vertebrate bioindicators of these agro-ecosystems which the VITIBIRD project aims to study. It also aims to determine whether specific agricultural and landscape practices can reduce any impacts by providing alternative habitats and reducing exposure to pesticides. VITIBIRD will rely on original and robust methodologies (national sampling plan, historical and long-term monitoring of bird populations, BACCHUS experimental site, renowned chemical and biological analysis laboratories, and experimental infrastructures). Firstly, we will set up innovative tools to measure the degree of contamination of vertebrates, living in wine-growing areas, by several pesticides. Using the BACCHUS experimental landscape system, we will examine the impact of agricultural practices and landscape complexity on this degree of contamination. Secondly, using historical monitoring, we will assess the evolution of avian biodiversity and bird populations in vineyards over the last 30 years. We will determine which species have declined the most during this period, and we will identify the characteristics that make species sensitive to farming practices. Using the BACCHUS scheme, we will test the impact of landscape and farming practices on biodiversity and bird demography. Thirdly, we will examine the relationships that exist between farming practices, landscape complexity and bird health, focusing particularly on physiological systems, which are essential to the proper functioning of the organism (hormonal axes, metabolism), and on the molecular damage that can be caused by pesticides. Using field and captive experiments, we will test the impact of the pesticides most commonly found in wild birds on these physiological systems (endocrine disruption, metabolism) and on these damages (oxidative stress, telomere erosion). Finally, we will evaluate the ecosystem services provided by birds in vineyards (pest control). We will use experimental approaches to measure trophic interactions between different bird species, grapevine pests and other invertebrate pest predators. Using the BACCHUS system, we will test the impact of farming practices and landscape complexity on the ecosystem services provided by birds and on the biological control of grapevine pests. VITIBIRD will rely on the complementary expertise of several research teams and institutes (CNRS, INRAE, MNHN, Universities) in ecotoxicology, agroecology, ecophysiology and conservation biology. This project has the potential to have a huge impact on the greatest number of people (scientists, students, media, managers) because it is based on a transdisciplinary approach and involves many stakeholders (scientists, students, communities, volunteers, associations, wine-growing professionals). In conclusion, VITIBIRD will improve our knowledge on (1) the transfer of pesticides into the environment, (2) the impact of pesticides and farming practices on biodiversity and health, and (3) the socio-economic benefits rendered by biodiversity in vineyards. Through the consortium's connections with multiple educational, socio-professional and decision-making bodies, this project should make it possible to provide advice and opinions to improve the management of the wine-growing environment.