Dietary niche partitioning among threatened ungulates in the desert ecosystems of northwestern China

In arid desert environments where resources are scarce, the mechanisms enabling stable coexistence among sympatric large ungulates remain poorly understood. To address this, fecal DNA metabarcoding was employed to assess dietary niche partitioning among three threatened species—Przewalski’s horse (PH; Equus ferus przewalskii), Asiatic wild ass (AWA; Equus hemionus), and goitered gazelle (GG; Gazella subgutturosa)—within the Kalamaili Nature Reserve, a critical hotspot for desert ungulates in China. Results revealed that the two equid species exhibited generalist feeding strategies, while GGs displayed dietary specialization. No clear trophic segregation was observed between reintroduced PHs and native species, indicating incomplete niche differentiation. Significant positive correlations were identified between dietary dissimilarity and geographic separation for both AWAs and GGs, with the GG diet showing greater geographic sensitivity. The native species demonstrated patch-specific dietary shifts, suggesting resource partitioning in response to environmental heterogeneity. The complementary use of spatially distinct resource patches reduced direct competition, thereby facilitating long-term, stable coexistence. However, patches with intermediate niche overlap showed the highest competition intensity, highlighting these transitional zones as critical targets for conservation. These findings provide a theoretical foundation for assessing the viability of reintroduced populations and guiding conservation strategies for threatened species, while emphasizing the importance of maintaining habitat heterogeneity.