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Biology (M.S.)

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The beautiful nuthatch, Sitta formosa, occurs in high-altitude evergreen and semi-evergreen forests throughout the south and southeastern extent of the Himalayan Mountains. Populations of S. formosa are small, declining and severely fragmented as a result of habitat degradation and fragmentation, and therefore it is considered vulnerable by the World Conservation Union and is included in the 2004 Red List of Threatened Species. I used ecological niche factor analysis to model the potential distribution and predict suitable habitat for S. formosa. By using 59 presence locations, collected from museum specimens and biodiversity surveys, and together with topographic and climate variables, I found S. formosa to be linked to much greater than average rainfall and greater than average slopes throughout the study area. S. formosapresence points were highly correlated with mature forests (frequency = 0.86), consisting of evergreen broadleaf, deciduous broadleaf and mixed forests. Core habitat (habitat suitability index ≥ 80) was predicted for 918,000 km2 within south and southeast Asia, yet current cover type maps indicate that only 57% of this area remains forested. Potentially, as much as 270,000 km2 of this historically highly suitable habitat has been converted to croplands. At a coarse scale, S. formosa populations that are threatened by agriculture and timber extraction are potentially most vulnerable to habitat loss, fragmentation and population isolation; however, a closer look at the biological and ecological needs of this species is necessary for effective management. The habitat suitability maps and models derived here with ecological niche factor analysis can be useful tools for identifying areas for future research, management and conservation of S. formosa.


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