Nationwide Assessment of the Factors Influencing Waterbird Abundance, Species Richness, and Community Composition in Small-Scale Irrigation Reservoirs

Small-scale irrigation reservoirs are common in agricultural landscapes, yet their importance for waterbirds remains insufficiently understood, as studies focused on natural wetlands or a few artificial sites. This study is the first nationwide assessment of waterbird use in such reservoirs. Using data from 66 reservoirs across geoclimatic regions of Israel, we examined how reservoir and landscape characteristics influence waterbird abundance, species richness, and community composition. 50 physical, climatic, water-quality, vegetation, spatial, and anthropogenic variables were analyzed with January 2020 waterbird census data, supplemented by six years of data (2015–2020) to assess temporal robustness.Waterbird abundance and species richness varied among reservoirs and were higher in warmer regions. Fishpond area within a 1-km radius was the strongest positive predictor of abundance and richness. Community composition differed significantly between fishpond-adjacent and other reservoirs: a distinct piscivorous guild, including storks, cormorants, gulls, and the vulnerable Greater Spotted Eagle was recorded almost exclusively at fishpond-adjacent sites, indicating functionally specific habitat value. These patterns were consistent across a single-winter snapshot and six-year monitoring record (r = 0.87–0.90). Larger reservoirs and greater water volume also increased waterbird use. These findings demonstrate that appropriately sited and managed irrigation reservoirs can support waterbird conservation alongside agriculture.