Trophic niche of coexistence of reintroduced scimitar-horned oryx and native dorcas gazelle in Sidi Toui National Park, Tunisia

Examining the trophic niche overlap of sympatric species is crucial for understanding fundamental concepts of community ecology and for the effective management of multi-species habitats within shared landscapes. Using plant (n = 85) and faecal (n = 300) samples collected in 2020–2021, the diet composition of the scimitar-horned oryx and the dorcas gazelle in the Sidi Toui National Park in Tunisia, was studied. Microhistological procedures combined with the use of n-alkanes and long-chain alcohols as faecal markers, were used to assess diet composition and the overlap of their trophic niches. During the dry season, the diet of the scimitar-horned oryx consisted primarily of Hyparrhenia hirta (L.) Stapf (35.6 %), while the gazelle's diet was dominated by Ziziphus lotus (L.) Lam. (66.4 %). In the wet season, Gymnocarpos decander Forssk. became the main dietary component for both antelope species. Pastoral species consumed by scimitar-horned oryx were richer in fiber fractions (neutral detergent fiber and acid detergent fiber) compared to those consumed by dorcas gazelles, which preferred species with high crude protein content. Our results show low trophic overlap between the two antelope species during both seasons, supporting their long-term coexistence in the park at current population densities.