Researchers from the University of Utah have conducted a comprehensive study to understand the characteristics that make certain bird species more prone to extinction. Their analysis, which included all 216 known bird extinctions since 1500, was designed to help inform conservation efforts for endangered bird species.
According to the research published recently, species that were most likely to become extinct were typically found on islands, had a larger body size, displayed sharp wing angles, lacked flight capabilities, and inhabited specific ecological niches. This groundbreaking study is the first to link these traits to the timing of bird extinctions, says lead author and graduate student Kyle Kittelberger.
Kittelberger, who is working on his dissertation studying how migratory songbirds’ bodies and wings have adapted to climate change, has a keen interest in understanding extinctions. He hopes that by learning from the past, we can better protect present and future bird species.
In their research, Kittelberger and his team utilized BirdBase, a comprehensive dataset of ecological traits for the world’s 11,600+ bird species. By comparing a diverse range of geographical, ecological, and life history traits, they were able to identify the characteristics that most significantly increase a bird’s risk of extinction.
Interestingly, the most critical trait associated with extinction is insularity, or endemicity to islands. Other traits linked to higher extinction risk, such as body size, wing shape, and ecological specialization, also tend to be associated with island-dwelling species.
Despite only about 2% of the world’s bird species having gone extinct since 1500, the start of the study period, many more species had disappeared prior to that date. However, reliable records of bird extinctions and their traits before this time are scarce. The 1500s also marked the beginning of systematic scientific observation and global exploration by Europeans, both of which significantly disrupted ecosystems worldwide.
Currently, the IUCN Red List of Threatened Species indicates that 1,314 bird species, approximately 12% of the total, are at risk of extinction. Some species, such as the ‘Akikiki endemic to the Hawaiian island of Kauai, are so rare that they are considered functionally extinct.
According to the study, the bird family that has suffered the most extinctions is Rallidae, or rails, which have lost 26 species. The entire Mohoidae family, also known as Hawaiian honeyeaters, is now completely extinct.
One surprising finding from the study was the correlation of wing shape with extinction risk. Birds with more pointed wings, indicative of stronger flying and dispersal abilities, were more likely to have gone extinct earlier than those with rounder wings. This may be because many of the extinct species were island dwellers, who would have needed strong flying abilities to reach these isolated locations in the first place.
The study also concluded that ecological specialists, who depend on specific ecological niches, are less able to adapt to disturbances such as invasive species or food source disruptions. Moreover, bigger birds were more likely to be hunted to extinction for food.
The research, published in the journal Avian Research, sets a significant precedent in understanding bird extinctions, providing invaluable insights for future conservation efforts. The study was supported by the University of Utah’s Graduate Research Fellowship.
