Evaluating Direct and Indirect Methods for Estimating Fallow Deer (Dama dama) Density Across Habitats in Rhodes Island, Greece: Implications for Management

The fallow deer (Dama dama) population on the island of Rhodes, Greece, constitutes one of the oldest extant free-ranging populations of this species. Robust population estimates are crucial for effective conservation and management. This study aimed to estimate deer population density, using a combination of direct and indirect approaches and to evaluate their relative performance. Surveys were conducted during the rutting season (October 2022) across mixed habitats, shrublands, and forests using Daytime Distance Sampling (DDS) and Spotlight Distance Sampling (SDS). Indirect estimates were derived using the Faecal Standing Crop (FSC) method during the same period, and, in January 2023, a revisit allowed estimation through the Faecal Accumulation Rate (FAR) method. All approaches indicated that mixed habitats supported the highest densities (7.85–10 individuals/km2), whereas shrublands (2.24–2.64 individuals/km2) and forests (0.65–2.96 individuals/km2) showed lower densities. Distance sampling methods performed best in mixed habitats, while FSC yielded more accurate and precise estimates than FAR across all habitats according to the Relative Net Precision index. These findings highlight the value of integrating complementary density methods and support the combined application of SDS and FSC for long-term population monitoring and evidence-based management.