Over the past 130,000 years, humans have exterminated hundreds of bird species. This means that the specific tasks of different birds in the wild are not being performed, leading to disruptions in ecosystems. A study by researchers from the University of Gothenburg estimates that around three billion years of unique evolutionary history have been lost in the extinctions.
From the well-documented dodo to the Hawaiian songbird kauai-o-o, which was declared extinct in 2023, researchers have evidence that humans have wiped out at least 600 bird species. In a new study based on the most comprehensive data to date on all known bird extinctions over the past 130,000 years, researchers have looked not only at the number of extinctions but also at the wider consequences for our planet.
Each bird species has a function
"The large number of bird species that have become extinct is of course a major part of the extinction crisis, but each species also has a job or function and therefore plays a very important role in its ecosystem. Some birds control pests by eating insects, others eat fruit and disperse the seeds so that more plants and trees can grow, and some, like hummingbirds, are important pollinators. As these species die out, so does the role they play," says lead author Tom Matthews from the University of Birmingham.
The study shows that the scale of human-caused bird extinctions to date has resulted in the loss of around three billion years of unique evolutionary history and seven per cent of global functional diversity in birds. This is a significantly higher amount than expected, based on the number of extinctions.
"Each species carries a certain amount of evolutionary history, so when a species goes extinct, it's basically like cutting off a branch on the tree of life," says Matthews.
Far-reaching consequences
Given the many important ecological roles of birds, extinction is likely to have far-reaching consequences. The aftermath includes reduced pollination of flowers, reduced seed dispersal, poorer regulation of insect populations, including many pests and disease vectors, as well as increased disease outbreaks due to reduced consumption of carcasses.
Important information
"Our results show that the biodiversity crisis is not just about the reduction in the number of species. The lost species had significant effects on ecosystems and to understand these, it is important to look at other aspects of diversity. This information is crucial for formulating effective targets for global conservation strategies, as well as for efforts to restore ecosystems and recreate wilderness," says Sören Faurby, Senior Lecturer at the University of Gothenburg and co-author of the study.
Scientific article in Science: The global loss of avian functional and phylogenetic diversity from anthropogenic
