Microplastic contamination in the pellets of the Egyptian vultures (Neophron percnopterus) as terrestrial bioindicators across contrasting landscapes in Türkiye

Microplastic (MP) contamination constitutes a widespread and intensifying global environmental challenge, adversely affecting aquatic, terrestrial, and atmospheric systems. Avian species are especially susceptible to microplastic exposure due to their ecological significance across diverse trophic levels and habitats, mostly through trophic transfer from consuming contaminated prey and inhaling airborne microplastics. This research uses regurgitated pellets of the Egyptian vulture as a pellet-based bioindicator tool to assess terrestrial microplastic contamination in two distinct regions of Türkiye (Ankara and Çorum). Here, a total of 307 microplastic particles were identified from 98 pellets, with a 93.33% overall occurrence rate and 100% contamination in Çorum samples. MP abundance was significantly higher in Çorum (mean = 15.0 ± 2.4 items per pellet) than in Ankara (mean = 1.15 ± 0.3; χ2 = 58.50, p < 0.001). The predominant polymers were polyethylene terephthalate (PET, 31.3%), polyacrylonitrile (PAN, 18.2%), and polypropylene (PP, 15.6%), with fibers being the dominant shape (70.7%) and transparent and blue the most frequent colors (50.2% combined). Statistical analyses revealed a negative correlation between MP size and pellet weight (r = –0.32, p < 0.001), confirming the influence of degradation and feeding behavior on MP retention. The widespread presence of MPs in this endangered species highlights trophic transfer and atmospheric deposition as key mechanisms of contamination. Egyptian vultures may serve as an effective bioindicator species for terrestrial microplastics, reflecting broader contamination within the terrestrial food web. These findings underscore the urgent need for improved plastic waste management in rural environments and the implementation of long-term monitoring to mitigate ecological and health risks.