A new study from Tel Aviv University and the Weizmann Institute reveals, over the last 20,000-50,000 years, birds have experienced major extinction events, caused mainly by humans. This extinction caused the loss of about 10%-20% of bird species.
The main cause of species extinction by humans today has evolved from hunting to the destruction of the natural habitats of animals. But the researchers hope their findings will serve as a warning signal about the bird species currently threatened with extinction.
Quoted from Phys.org, this study was led by Prof. Shai Meiri of the School of Zoology at The George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at Tel Aviv University, and Amir Fromm of the Weizmann Institute of Science. The scientific paper was published in the Journal of Biogeography.
Extinction caused by humans
"We conducted a comprehensive review of the scientific literature, and for the first time collected quantitative data on the number and traits of extinct bird species worldwide," the researchers wrote.
The researchers said birds that went extinct in the last 300 years were relatively well known, while species were previously known to science from remains found at archaeological and paleontological sites around the world.
"Overall we were able to list 469 bird species that went extinct over the last 50,000 years, but we believe the actual number is much higher," they said.
Researchers believe that the massive extinction was caused primarily by humans hunting birds for food, or by animals being brought to the island by humans eating birds and/or their eggs.
This assumption is based on the fact that most of the remains of bird bones found at human archaeological sites, which appear to be birds consumed by residents. And in many cases, the extinction of birds occurred shortly after the arrival of humans.
Extinct birds
Through this research, most of the extinct bird species have three main characteristics:
About 90% live on the island. When humans arrived on the island, the birds were hunted by them, or became victims of other animals introduced by humans, such as pigs, mice, monkeys and cats.
Most of the extinct bird species were large, some very large (up to 10 times larger than the living species). The larger birds provide humans with large amounts of food, making them the target of choice for hunters. Previous studies have found a similar phenomenon among mammals and reptiles, especially lizards and turtles that live on islands. Larger lizards and turtles were hunted by humans and became extinct
Most extinct bird species were flightless, and often could not escape their pursuers. The study found that the number of flightless bird species that became extinct was twice the number of flightless species extant today. Overall, 68% of the flightless bird species known to science became extinct. One of the more famous examples is the moa in New Zealand. A total of 11 species of moa became extinct within a period of 300 hundred years due to hunting by humans.
"Our study shows that before the great extinction event thousands of years ago, more large, even giant, flightless birds lived in our world. And the diversity of birds living on islands was much greater than today," said researcher.
"We hope our findings can serve as a warning signal about bird species that are currently threatened with extinction, and it is therefore important to examine whether they share similar features. However, it should be noted that conditions have changed a lot, and today the main cause for extinction of the species by humans is not hunting but the destruction of natural habitats."