Study of the habitat, diet, and behavior of Sambar Deer (Rusa unicolor, Kerr, 1792), of the Powderhorn Wildlife Management Area, Calhoun County, Texas, USA.

This dissertation presents a comprehensive 16-month mixed-methods investigation into the ecology, diet, and habitat use of introduced Sambar deer (Rusa unicolor) at the Powderhorn Wildlife Management Area (WMA) in Calhoun County, Texas. The study integrates classical field techniques spotlight surveys, walked transects, and direct observation with modern analytical approaches, including microhistological analysis, Chamrad & Box point-frame sampling, and advanced statistical modeling (GLMM, NMDS, beta regression). Habitat characterization was conducted using ecological site classifications and vegetation cover metrics, providing a foundation for interpreting forage selection, and calculating Dietary Importance Value Index (IVI) at both species and functional group levels. Findings reveal that Sambar deer exhibit ecological flexibility and behavioral plasticity, with seasonal shifts between browsing and grazing. Habitat use was strongly associated with freshwater marshes and oak-yaupon motte complexes, which provided critical forage, thermal refuge, and loafing cover, particularly during drought conditions. Dietary analysis confirmed a dominant reliance on Ilex species, especially Yaupon holly, supplemented by graminoids and aquatic plants during dry periods. Social behavior was characterized by solitary adult males and loosely structured maternal groups. Interspecific interactions showed minimal conflict, though Sambar deer consistently avoided cattle, suggesting niche partitioning. The estimated population of approximately 485 individuals was within the ecological carrying capacity of the WMA, supporting sustainable hunting and habitat preservation goals. Methodologically, microhistological techniques provided high-resolution species identification, while Chamrad & Box analysis offered a practical, field-friendly approach for landowners and managers. Both methods yielded complementary insights into forage composition and dietary patterns. Comparative analysis with the St. Vincent Island population highlighted how habitat structure and accessibility influence detectability and behavior. This research contributes to the growing body of literature on non-native ungulate management in coastal ecosystems and demonstrates the value of integrating habitat characterization with dietary analysis. It advocates adaptive management strategies that balance recreational hunting with long-term ecological integrity, emphasizing the importance of preserving freshwater marshes and woody motte complexes. Future research should expand dietary sampling into spring and summer, investigate sex-based dietary differences, and explore the ecological role of aquatic foraging in Sambar deer.