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European Roller Chicks in Cropland Landscapes Differed in Specific Antioxidant and Immune Markers

Immature European Roller perched among branches
Research · Molecular biology & biochemistry

European roller (Coracias garrulus) chicks raised in cereal-dominated agricultural landscapes in central Italy differed from chicks in more heterogeneous landscapes in a small number of molecular, antioxidant and immune measures. Most genes and physiological markers did not differ between the habitat types, so the study points to specific physiological adjustments rather than a broad deterioration in condition.

The study was carried out in the provinces of Rome and Viterbo in 2023 and 2024. All birds bred in nest boxes mounted on high-voltage pylons, which helped standardise nesting conditions. The landscape within one kilometre of each nest was classified either as cereal-cropland dominated or as a more mixed mosaic containing grasslands, pastures, fallow fields, bushes and trees.

Blood was collected when the chicks were 21 days old. Transcriptomics — measuring which genes are active and how strongly they are expressed — was carried out on 16 chicks, eight from each habitat type and one from each brood. A broader set of physiological and immune measurements included 51 chicks: 24 from cropland-dominated landscapes and 27 from mixed landscapes.

Antioxidant systems shifted in different directions

Nine genes had significantly lower expression in chicks from the cropland sites. Among them were CAT, GSTO1 and GSTT1. CAT encodes catalase, an enzyme that breaks down hydrogen peroxide and helps prevent oxidative damage. GSTO1 and GSTT1 belong to glutathione-related enzyme systems involved in handling reactive or potentially harmful compounds. Genes linked to mitochondrial, metabolic and other cellular processes also differed, and the catalase complex was particularly represented among the affected genes.

The blood measurements showed a related but not uniform antioxidant response. Chicks from cropland-dominated landscapes had lower catalase activity, but higher activity of glutathione peroxidase, another antioxidant enzyme that helps remove peroxides. Because these two antioxidant systems changed in opposite directions, the authors interpret the pattern as different regulation of oxidative physiology between habitats rather than a simple overall reduction in antioxidant defence. DNA damage did not differ between the groups.

Lower IgY did not necessarily mean weaker immunity

Cropland-raised chicks also had lower concentrations of immunoglobulin Y (IgY), the main antibody class in birds that contributes to adaptive, antibody-mediated immunity. IgY concentration is not a simple measure of “immune strength”: higher levels can reflect recent or ongoing exposure to pathogens, but can also reflect an individual’s capacity to mount and maintain an antibody response. The authors therefore suggest that the lower IgY levels could reflect differences in parasite or pathogen exposure between habitats, or differences in immune status and parental exposure history.

Several other immune and physiological measures showed no habitat-related difference, including superoxide dismutase activity, haptoglobin, bacterial-killing ability, haemagglutination and haemolysis. Body condition was also similar, and most genes did not differ in expression. The authors therefore describe the overall molecular and physiological differentiation as small.

The environmental cause remains unresolved

The study did not identify what produced the differences. The authors discuss pesticide exposure, warmer and drier cropland microclimates, diet and nutritional conditions, pathogen exposure and parental effects as possibilities for future study. Parents may also forage beyond the immediate nesting landscape and partly compensate for local differences in food availability or quality.

Larger studies across more landscapes will be needed to test how general the pattern is and to determine which environmental factors actually drive the molecular and physiological differences. The study was published online on 19 June 2026 in Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology.

Sources and image credit

  1. Costantini, D., Berardi, B., Cannarella, S., Damiani, G., Filippi, S., Czirják, G. Á., Messina, S., Franchini, P., & Dell’Omo, G. (2026). Agricultural landscapes reshape progeny through transcriptomic and physiological changes. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 319, 112039. https://doi.org/10.1016/j.cbpa.2026.112039Primary peer-reviewed study, published online 19 June 2026.

Image: I Love Trees — immature European Roller in Kruger National Park, South Africa; Wikimedia Commons/Flickr; high-resolution image of a young bird, not from the Italian study · CC BY 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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