The article presents a framework to assess the ecological and societal consequences of bird declines, focusing on the global avifauna. The authors compiled databases on bird conservation status, distribution, and functional roles, and developed a stochastic model to forecast changes. They found that 21% of bird species are currently extinction-prone, and 6.5% are functionally extinct, contributing minimally to ecosystem processes. By 2100, projections indicate that 6-14% of all bird species will be extinct, and 7-25% (28-56% on oceanic islands) will be functionally extinct. This decline will likely affect important ecosystem processes such as decomposition, pollination, and seed dispersal. The study highlights the need for conservation efforts to prevent further bird extinctions and their potential impacts on ecosystems.The article presents a framework to assess the ecological and societal consequences of bird declines, focusing on the global avifauna. The authors compiled databases on bird conservation status, distribution, and functional roles, and developed a stochastic model to forecast changes. They found that 21% of bird species are currently extinction-prone, and 6.5% are functionally extinct, contributing minimally to ecosystem processes. By 2100, projections indicate that 6-14% of all bird species will be extinct, and 7-25% (28-56% on oceanic islands) will be functionally extinct. This decline will likely affect important ecosystem processes such as decomposition, pollination, and seed dispersal. The study highlights the need for conservation efforts to prevent further bird extinctions and their potential impacts on ecosystems.