Bird declines are a major threat to global ecosystems, with significant consequences for biodiversity and ecosystem services. A study by Çağan H. Şekercioğlu, Gretchen C. Daily, and Paul R. Ehrlich highlights that 21% of bird species are currently extinction-prone, and 6.5% are functionally extinct, contributing little to ecosystem processes. By 2100, 6–14% of all bird species are expected to be extinct, with 7–25% (28–56% on oceanic islands) functionally extinct. Important ecosystem processes such as decomposition, pollination, and seed dispersal are likely to decline. The study analyzed a comprehensive database of bird species, their conservation status, distribution, and life histories. It used a stochastic model to forecast changes and compared current distributions of threatened birds with those projected for 2100 under three scenarios. The results show that extinction-prone birds are not randomly distributed across functional groups or guilds. Frugivores, herbivores, omnivores, piscivores, and scavengers are particularly at risk, with higher concentrations leading to community disassembly and more pronounced ecological consequences. The study also found that 43% of threatened bird species are endangered, critically endangered, or extinct in the wild, making up 7% of all historic bird species. These birds contribute little to ecosystem processes compared to the rest of the avifauna. Functional extinction occurs when species are so rare or have declined so much that they no longer contribute to ecosystem functions. The study defines functionally deficient species as those with recent and substantial declines in abundance or geographic range. The study projects that by 2100, 6–14% of all bird species will be extinct, 7–25% functionally extinct, and 13–52% functionally deficient. Certain groups, such as frugivores, herbivores, nectarivores, piscivores, and scavengers, are expected to experience higher-than-average extinction rates. Specialists and monospecific genera are also at higher risk. Forest, marine, and wetland habitats, as well as regions with many island birds, are projected to experience the highest proportions of real and functional extinctions. The study emphasizes the importance of birds in ecosystem services, such as pollination, seed dispersal, and nutrient cycling. The loss of these services could have significant consequences for plant populations and community dynamics. The study also highlights the role of scavenging birds in nutrient recycling and disease control, and the potential consequences of their decline, such as increased disease outbreaks. The study concludes that bird declines are a critical issue with far-reaching consequences for ecosystems and society. Conservation efforts are needed to prevent further declines and to protect the ecosystem services provided by birds. The study underscores the importance of understanding and preventing declines in bird populations toBird declines are a major threat to global ecosystems, with significant consequences for biodiversity and ecosystem services. A study by Çağan H. Şekercioğlu, Gretchen C. Daily, and Paul R. Ehrlich highlights that 21% of bird species are currently extinction-prone, and 6.5% are functionally extinct, contributing little to ecosystem processes. By 2100, 6–14% of all bird species are expected to be extinct, with 7–25% (28–56% on oceanic islands) functionally extinct. Important ecosystem processes such as decomposition, pollination, and seed dispersal are likely to decline. The study analyzed a comprehensive database of bird species, their conservation status, distribution, and life histories. It used a stochastic model to forecast changes and compared current distributions of threatened birds with those projected for 2100 under three scenarios. The results show that extinction-prone birds are not randomly distributed across functional groups or guilds. Frugivores, herbivores, omnivores, piscivores, and scavengers are particularly at risk, with higher concentrations leading to community disassembly and more pronounced ecological consequences. The study also found that 43% of threatened bird species are endangered, critically endangered, or extinct in the wild, making up 7% of all historic bird species. These birds contribute little to ecosystem processes compared to the rest of the avifauna. Functional extinction occurs when species are so rare or have declined so much that they no longer contribute to ecosystem functions. The study defines functionally deficient species as those with recent and substantial declines in abundance or geographic range. The study projects that by 2100, 6–14% of all bird species will be extinct, 7–25% functionally extinct, and 13–52% functionally deficient. Certain groups, such as frugivores, herbivores, nectarivores, piscivores, and scavengers, are expected to experience higher-than-average extinction rates. Specialists and monospecific genera are also at higher risk. Forest, marine, and wetland habitats, as well as regions with many island birds, are projected to experience the highest proportions of real and functional extinctions. The study emphasizes the importance of birds in ecosystem services, such as pollination, seed dispersal, and nutrient cycling. The loss of these services could have significant consequences for plant populations and community dynamics. The study also highlights the role of scavenging birds in nutrient recycling and disease control, and the potential consequences of their decline, such as increased disease outbreaks. The study concludes that bird declines are a critical issue with far-reaching consequences for ecosystems and society. Conservation efforts are needed to prevent further declines and to protect the ecosystem services provided by birds. The study underscores the importance of understanding and preventing declines in bird populations to