Abstract:[Objectives] In the process of protecting flagship species, the national park often has an ancillary protection effect on other species with similar distributions, thus promoting the conservation of species with limited research. As an endemic bird on the southeastern edge of the Qinghai-Tibet Plateau in China, Sichuan Treecreeper Certhia tianquanensis has a narrow territory with a strong preference for pristine high-elevation coniferous forests, and part of its range coincides with that of Giant Pandas Ailuropoda melanoleuca. Loss of pristine habitat due to human activities are threatening the survival of the Sichuan Treecreeper, leading to its classification as a national Grade II wildlife species in 2021. Although the habitat selection of Sichuan Treecreeper has not been well studied, its habitat may have ancillary protection from the flagship species, Giant Pandas. [Methods] In order to verify whether this ancillary protection effect is effective in maintaining the core habitat of Sichuan Treecreeper, a species distribution model was applied, in conjunction with functional habitat patch classification model, to predict and functionally classify its habitat. In addition, the degree of overall habitat fragmentation was quantified. Five commonly used metrics, Patch number, Patch density, Landscape shape index, Largest patch index and Correlation length were selected to measure the degree of habitat fragmentation of Sichuan Treecreeper. In this study, habitat of Sichuan Treecreeper was categorized into interior patches, small patches, transitional patches, edge patches, perforated patches, and other patches of undetermined category. [Results] Overlay analysis of model predictions with protected areas showed that Sichuan Treecreeper had a total potential distribution area of approximately 195 800 km2, with 26.9% of its habitat under protection, most of which belonged to the core patches. However, only about 18.7% of the area belonged to the core range of Sichuan Treecreeper, indicating that the overall habitat was severely fragmented (Fig. 1). The interior habitat mainly located in the central and northeastern parts of Sichuan Province, the southern part of Gansu Province, and the southern part of Shaanxi Province in China. The high density of patches indicated that the habitat of Sichuan Treecreeper suffered from anthropogenic disturbance and poor connectivity. The environmental variable that contributed most to model construction was elevation (22.6%), followed by warmest quarter precipitation (13.5%), driest quarter mean temperature (12.9%), and vegetation cover type (11.0%) (Fig. 2). The potential habitat of Sichuan Treecreeper distributed near 2 500 m a.s.l., mainly inhabiting closed evergreen coniferous forests and closed evergreen broadleaf forests close to water sources. Sichuan Treecreeper prefers forests with steeper slopes and low human disturbance. Within a certain range, the Sichuan Treecreeper has an optimal adaptation zone to climatic conditions, with no clear preference for either slope aspect or forest cover. Among all the protected areas, the Giant Panda National Park protected the largest area of Sichuan Treecreeper habitat, accounting for 8.4% of the total potential distribution area (Table 1). [Conclusion] In conclusion, Sichuan Treecreeper received positive ancillary protection effects from the Giant Panda National Park, in which the core distribution area was well covered. However, the marginal fragmented habitat of Sichuan Treecreeper lacks adequate protection. According to the protection gap analysis, the unprotected core habitat is located in the southern part of Gansu Province (northeastern Diebu County). Detailed surveys of Sichuan Treecreeper are needed in this area to determine whether it is the actual habitat of the Sichuan Treecreeper. For the planning of future conservation measures, it is important to strengthen the restoration of connectivity in edge habitats, which is crucial for maintaining and restoring the connectivity of its distribution range.
