University of Tehran Journal of Natural Environment 2008-7764 78 4 2026 01 21 Effects of hydrological fluctuations and drought on the diversity of migratory birds in the Gandoman Wetland Effects of hydrological fluctuations and drought on the diversity of migratory birds in the Gandoman Wetland 649 661 105317 10.22059/jne.2025.401385.2837 FA Marziyeh Ghaffari Farsani Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. Mansoureh Malekian Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. 0000-0002-6387-0850 Journal Article 2025 09 02 The Gandoman Wetland, one of Iran’s vital habitats, serves as an important stopover and habitat for migratory birds. This study aimed to analyze the effects of hydrological fluctuations and drought on the diversity and abundance of migratory birds from 2011 to 2023. The standardized precipitation index (SPI), mean annual temperature, and surface water cover index (NDWI) were extracted using Landsat satellite images and analyzed with the nonparametric Mann-Kendall test and Pearson correlation analysis. Field bird census data were collected between 2011 and 2023. The results showed a significant decreasing trend in NDWI (Z= −2.68, Sen's slope= −5.83) of the wetland surface, simultaneously with increasing temperature and decreasing rainfall, which led to a significant decline in species diversity (Shannon and Simpson indices) and bird evenness (Camargo and Simpson indices). The positive correlation of NDWI with SPI (r= 0.48) and annual rainfall (r= 0.50), along with a negative correlation with temperature (r= −0.58), indicates the high sensitivity of the wetland to climate change. The decrease in bird populations evenness during dry years confirms the dominance of certain species and suggests a shift in species composition. Overall, the results indicate that the Gandoman Wetland has experienced a significant decrease in NDWI and an increase in temperature, resulting in a decline in bird diversity and evenness. Given the wetland's critical role in the bird migration cycle, targeted and strategic conservation measures are essential. Such efforts should integrate remote sensing data, climate parameters, and field observations to ensure effective management. The Gandoman Wetland, one of Iran’s vital habitats, serves as an important stopover and habitat for migratory birds. This study aimed to analyze the effects of hydrological fluctuations and drought on the diversity and abundance of migratory birds from 2011 to 2023. The standardized precipitation index (SPI), mean annual temperature, and surface water cover index (NDWI) were extracted using Landsat satellite images and analyzed with the nonparametric Mann-Kendall test and Pearson correlation analysis. Field bird census data were collected between 2011 and 2023. The results showed a significant decreasing trend in NDWI (Z= −2.68, Sen's slope= −5.83) of the wetland surface, simultaneously with increasing temperature and decreasing rainfall, which led to a significant decline in species diversity (Shannon and Simpson indices) and bird evenness (Camargo and Simpson indices). The positive correlation of NDWI with SPI (r= 0.48) and annual rainfall (r= 0.50), along with a negative correlation with temperature (r= −0.58), indicates the high sensitivity of the wetland to climate change. The decrease in bird populations evenness during dry years confirms the dominance of certain species and suggests a shift in species composition. Overall, the results indicate that the Gandoman Wetland has experienced a significant decrease in NDWI and an increase in temperature, resulting in a decline in bird diversity and evenness. Given the wetland's critical role in the bird migration cycle, targeted and strategic conservation measures are essential. Such efforts should integrate remote sensing data, climate parameters, and field observations to ensure effective management. https://jne.ut.ac.ir/article_105317_098c851a90d4f0c98035214f1414bfa1.pdf