Abstract:[Objectives] To understand the distribution and expansion of the reintroduced population of Crested Ibis Nipponia nippon, we investigated the distribution of nest sites in this species with a reintroduced population in Dongzhai, Henan Province, China. [Methods] From 2014 to 2022, we investigated the nests of rewilding Crested Ibis and its descendants in Henan Dongzhai National Nature Reserve and its surrounding area. We estimated the degree of concentration of these nests relative to the release site by a circular distribution method using Oriana 4.01 (Kovach Computing Services, Wales, UK). We calculated the distribution of the nesting area (the area where 95% of the nest sites are located) and core nesting area (the area where 50% of the nest sites are located) using a fixed kernel estimation method in ArcView GIS 3.3. In addition, we overlaid the map of nest sites, landscape coverage map, and the digital elevation model map using ArcMap 10.7 software (ESRI) to investigate the nest-site selection of this species. Using the one sample t-test, we compared the average elevation difference between the nest sites and the nesting range. [Results] The distances between most nesting sites and the release site are within 80 km (81 vs. 84) (Fig. 1 and 2). The average distance was 12.82 ± 14.11 (SD) km (n = 84), and the average azimuth was 138.99° ± 82.44° (SD) (Rayleigh’s z test:Z = 10.60, P < 0.01) (Fig. 3). The area of the core nesting ranges and nesting ranges are 74.43 km2 and 549.66 km2, respectively (Fig. 4). The average elevation of the nest sites is 103 ± 43 (SD) m, which is significantly lower than the average altitude of the nesting ranges (t =﹣5.48, df = 83, P < 0.01). Most nest sites are distributed in the adjacent paddy fields and forests (Fig. 1). The distribution map of the breeding area by years shows that the breeding area expands in the direction of northwest to southeast (Fig. 5), which is consistent with the analysis result of circular distribution. [Conclusion] Our research described the nest site’s distribution characteristics and expansion trends of the reintroduced Crested Ibis population in Dongzhai. It can provide a reference for the protection of potential breeding areas and habitats of wild Crested Ibis, and optimize the allocation of human and material resources in the protection work.
