Organic food is healthier for birds too

Pair of Grey Partridge (photo V. Bretagnolle)

The effects on the health of partridges fed on conventional and organic cereals were studied under natural conditions. The results show that in less than 10 weeks, the behaviour, immunology and physiology of individuals consuming conventionally grown food deteriorate significantly. This study was published in March 2021 in Environmental Pollution by researchers from the Centre d’études biologiques de Chizé (CNRS/La Rochelle University) and the Biogeosciences laboratory (CNRS/UBFC).

Exposure to plant protection products: effects on bird populations

The intensification of agriculture is at the root of an unprecedented decline in biodiversity, particularly among birds, and the extensive use of plant protection products is one of the causes. The impact of pesticides is recognised by the lethal effects following exposure or ingestion of massive doses and/or particularly toxic molecules. However, these negative effects are largely underestimated by studies that are only concerned with acute exposure to larger doses. In the long term, chronic exposure to low doses can have equally devastating effects on the survival or reproduction of individuals and thus more generally on the scale of the population and ecosystems.

A deterioration in the health of birds fed “non-organic” cereals

By feeding two groups of grey partridges (birds that are emblematic of agricultural plains) for several weeks with cereals that differed exclusively in terms of their origin, either organically grown (without the use of pesticides) or conventionally grown (use of different pesticide molecules during the growth of the plant), the researchers were able to demonstrate a clear deterioration in the health of the birds consuming ‘non-organic’ food. These birds reproduced less well and showed clear signs of physiological and behavioural alterations. Among the effects demonstrated in this study, their immune systems were overexpressed, physiological stress was increased and the colouration of the males was duller, indicating poorer health. In addition, the body weight of the females fed conventional grain increased, which could be related to an endocrine disruption in the storage of reserves in the adipose tissue.

An innovative experimental design

Unlike the vast majority of studies that test the effects of pesticides, the toxic molecules were not added to the feed. Indeed, this study shows that cereals from conventional agriculture contain pesticide residues and induce observable disturbances in the birds, which may partly explain their disappearance from the agricultural landscape.

In conclusion, this study highlights the lack of analysis of the long-term impacts of pesticides in natural conditions before they are marketed and demonstrates that in birds, the consumption of food from organic farming has beneficial effects on their health, reinforcing the approach and concept of environmental health (One Health).

Contacts :
University of Burgundy / UBFC / Biogeosciences Laboratory
Audrey Rahali – 06 77 43 47 24 – audrey.rahali@u-bourgogne.fr
Anne-Lise Santoni – 03 80 39 63 57 – anne-lise.santoni@u-bourgogne.fr

Researchers contacts :
Biogeosciences Laboratory CNRS/ UBFC
Researcher University of Burgundy: Jérôme Moreau – 06 81 57 84 57 – Jerome.moreau@u-bourgogne.fr
Centre d’Études Biologiques de Chizé, CNRS / La Rochelle University,
Researcher CNRS: Vincent Bretagnolle – 06 15 29 24 43 – breta@cebc.cnrs.fr