July 3, 2006 — By the end of the 21st century, 12 percent of all known bird species may become extinct due to human activities, according to an alarming new study that also determined birds are now dying off at a rate of one species per year.
The new data significantly increase the rate of avian extinctions, as researchers beforehand thought one species was lost every four years. Even the new extinction rate is expected to skyrocket to 10 bird species lost per year in the near future.
The dismal prediction is due to human-related impacts such as habitat destruction, invasive species and climate change.
"Impact is a product of ever-increasing (human) population, ever-higher consumption rates and expectations, and the uses of inappropriate technologies that destroy habitats and individual organisms on an enormous scale," said Peter Raven, one of the study’s authors.
Raven, president of the Missouri Botanical Garden, and his colleagues discovered that other studies were not including three factors in their analyses of bird extinctions.
These factors include the continual identification of extinct species from skeletal remains, numerous missing species that have not yet been declared extinct, and extinction rates not using the date the bird was first identified as a baseline. The latter refers to the fact that scientists first identified most known bird species after 1850.
Without human impacts, the natural rate of bird extinction would only be one bird species lost per century, according to the researchers, whose study is published in the current Proceedings of the National Academy of Sciences.
The study named many recent extinct, or presumed extinct, bird species. These include the Hawaiian honeycreeper, the Mauritius blue pigeon, the Kosrae starling and 151 additional species. The study also mentions that at least 25 bird species, such as the Campbell Island Teal duck, would have gone extinct during the past three decades were it not for conservation efforts.
"But even for birds, capacities run out, and the very large numbers of species to be protected throughout the world will to some extent overwhelm the total energy, numbers of people and funds necessary to preserve them," Raven told Discovery News.
According to the researchers, climate change alone threatens 15-37 percent of all bird species, depending on which climate scenario will unfold. In many regions that already have experienced several avian extinctions, surviving species are literally clinging to life in the uppermost forested elevations, the ornithologists suggest.
If temperatures continue to rise, these birds will have no higher elevations in which to escape. Certain species in the coastal forests of Brazil, for example, fall into this category.
Perhaps most disturbing is the fact that birds are faring better than most other animals and plants, which are experiencing extinctions at even higher rates.
"Birds are literally the bellwether of what’s going on," explained Raven. "The best-known group of organisms of their size, they give us a fair minimum estimate of extinction rates. Overall, we continue to estimate that more than two-thirds of all species of non-bacterial organisms are likely to become extinct during the course of this century, but only an eighth to a quarter of the bird species."
Thomas Lovejoy, president of the H. John Heinz III Center for Science, Economics and the Environment in Washington, D.C., told Discovery News that the new study "is a very good in-depth reanalysis of the extinction problem primarily from the perspective of birds."
Lovejoy added, "It confirms what most of us have anticipated from intuition, namely that the problem is even more grave than previous figures have indicated. And if that is so for birds, it is likely to be even more serious in many other groups of organisms."
