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Roe Deer Diet Markers Shifted With Season and Sex in Northern Iran

Young male European roe deer standing among green vegetation
Research · Ecology

A study of a protected European roe deer (Capreolus capreolus) population in northern Iran found that the nutritional composition reflected in droppings varied with season and sex. The research article was published online in Global Ecology and Conservation on 11 June 2026.

Seasonal samples from a protected landscape

The researchers collected fresh faecal samples across all four seasons, dried and powdered them, and analysed 13 chemical components. They then related those measurements to season, elevation, habitat greenness and sex. Habitat was represented partly by NDVI, a satellite-based index of vegetation greenness: higher values generally indicate denser or more photosynthetically active vegetation, not a particular plant species. This non-invasive approach avoids capturing the deer, but faecal chemistry is an indirect dietary marker. What remains in droppings reflects both what the animal ate and what it digested or absorbed, so a high or low faecal value cannot automatically be read as the same high or low concentration in the plants consumed.

Clear differences through the year

The strongest pattern was seasonal. Faecal dry matter was lower in autumn. Summer samples contained less fat and starch, more fibre fractions associated with lower digestibility, and less hemicellulose, while spring was characterised by more organic matter and less ash. In practical terms, the chemical profile of what remained after digestion changed markedly through the year, consistent with seasonal shifts in the types or quality of forage being used. The measurements do not by themselves show exactly which plant species caused those changes.

Sex was also related to some of the measured components. Male faecal samples contained more fat and fatty acids than female samples, with the difference particularly evident in summer. Higher elevation and higher NDVI were also associated with more faecal fat and fatty acids. By contrast, crude protein, nitrogen and non-fibre carbohydrates showed no significant relationship with season, sex, elevation or NDVI. Together, these results show that sex, elevation and vegetation greenness were associated with the fat-related components measured in the faeces, while several other nutrient measures did not show the same pattern.

Why habitat context matters

For a selective browser such as roe deer, the quality and availability of young shoots, leaves and other plant material can change rapidly with plant growth, temperature and moisture. Elevation and vegetation cover can also determine where suitable forage is available. By analysing season, habitat and topography together, the study places the chemical findings in the landscape in which the animals were feeding.

The authors argue that the patterns have practical implications for habitat management. In particular, they highlight high-elevation areas with high NDVI because these conditions were associated with more faecal fat and fatty acids, and they recommend maintaining diverse vegetation to accommodate seasonal changes in nutrient components. They also emphasise that sex-specific nutritional patterns should be considered, especially the higher fat and fatty-acid values recorded in males.

Sources and image credit

  1. Amininasab, S. M., & Teimouri Yansari, A. (2026). Relationships of season, topography, habitat, and sex with the diet components of roe deer. Global Ecology and Conservation, 69, e04294. https://doi.org/10.1016/j.gecco.2026.e04294Primary open-access field study from northern Iran, first published online 11 June 2026. Fresh faecal samples collected across four seasons in 2023–2024 were analysed for 13 chemical components and related to season, elevation, NDVI and sex.

Image: Charles J. Sharp / Wikimedia Commons — young male European roe deer at Cumnor, Oxfordshire, United Kingdom, 4 April 2024; representative species image, not a deer from the northern Iran study · CC BY-SA 4.0 · Source

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