Are Treatment Wetlands suitable surrogate habitats for birds? A study on avian diversity in Northern Italy

Treatment Wetlands (TWs) are artificial wetlands designed for wastewater treatment. TW technology combines economic utility with ecological and conservation benefits. This study investigates whether TWs can serve as surrogate habitats for birds by comparing them with semi-natural wetlands and the surrounding landscape. Specifically, we assessed bird diversity across three habitat types (TWs, semi-natural wetlands, and dry landscape as control) using Hill numbers and analyzed differences in waterbird guilds. Additionally, generalized linear models (GLMs) were applied to explore relationships between environmental variables and bird diversity. Bird diversity data were collected through point counts within 300x300 m plots, while environmental variables were derived via photointerpretation. Results showed no significant differences in overall bird diversity between TWs, semi-natural wetlands, and control sites. However, guild-specific analysis revealed that waterbird diversity in TWs exceeded that of the controls and was comparable to semi-natural wetlands. Furthermore, the extent of free water, reedbed coverage, and urbanization degree of the surrounding matrix were positively associated with bird diversity. These findings suggest that TWs can function as suitable surrogate habitats, providing ecological value akin to semi-natural wetlands for most of the tested waterbird guilds. In each folder, you can find the various dataframes related to a sampling season. These include both those containing bird abundance data and environmental data. Additionally, the R script is also provided.