Mankind’s colonization of the globe over the past 50,000 years has had some pretty catastrophic consequences for other species, including several hundred types of bird. According to a new study in the Journal of Biogeography, human activities have caused the extinction of at least 469 avian species since the end of the Pleistocene, including more than two-thirds of all flightless birds.
The study authors examined the scientific literature relating to all avian species that have become extinct worldwide in the last 50 millennia. In doing so, they noticed a number of clear patterns that strongly suggest that our ancestors were the main driving force behind many of these extinctions.
Notably, 90 percent of all extinct birds lived on islands and disappeared shortly after the arrival of humans. This seems pretty logical, as birds and their eggs would have been preyed on by people and other animals that may have tagged along with these bipedal immigrants.
The researchers also found 116 examples of flightless birds that have become extinct within this timeframe. Given that there are only 54 species of flightless bird alive today, this figure represents a huge proportion of all grounded avian species to have existed over the past 50,000 years.
Naturally, flightless birds make easier prey than those that can take to the skies, so it makes sense that their numbers would have plummeted once humans entered their habitats. In New Zealand, for instance, 11 different species of flightless moa became extinct within a few centuries of man’s arrival.
Additional analysis revealed that the average body mass of all extinct bird species was around seven times greater than that of extant avian varieties. This finding implies that larger birds were significantly more likely to be hunted by humans, and aligns with previous studies which have indicated that larger animals tend to be the first to become extinct once people arrive in a new location.
“Altogether we were able to list 469 avian species that became extinct over the last 50,000 years, but we believe that the real number is much higher,” said study author Professor Shai Meiri in a statement. In their write-up, the researchers explain that this suspicion is supported by the fact that “many fossilized birds were found that are not yet fully described ... and were thus excluded from our study.”
In addition to highlighting the devastating impact that humans have had on other animals throughout history, the findings of this study also enhance our understanding of the avian faunas that existed in the past.
For instance, the researchers conclude that “[b]efore the Pleistocene-Holocene extinctions, many more species of birds were large or even gigantic,” while “[f]lightlessness, a rare trait today, was much more common.”