Human activities have caused the extinction of about 1,400 bird species, a new study shows, double the number previously estimated. This has significant implications for the current biodiversity crisis. Islands such as Hawaii, Tonga and the Azores were once pristine paradises, but have been transformed since human settlement. These changes include widespread deforestation, overhunting and the introduction of non-native species, resulting in the loss of large numbers of bird species.
While the extinction of many birds has been documented since the 1500s, our understanding of the fate of previous species relies on fossils, and these records are limited because birds' bones are light and thin and disintegrate over time. This obscures the true picture of global species extinction.
Researchers currently believe that 1,430 bird species (nearly 12%) have become extinct in modern human history since the Late Pleistocene, about 130,000 years ago, with the vast majority being wiped out directly or indirectly by human activities.
The study, led by the UK Center for Ecology and Hydrology (UKCEH) and published in Nature Communications, used statistical modeling to estimate the number of undetected bird extinctions.
Dr Rob Cooke, lead author of the study and an ecological modeller at the UK Ecological Research Centre, said: "Our research shows that humans have had a far greater impact on bird diversity than previously thought. Humans have rapidly destroyed bird populations through habitat loss, over-exploitation, and the introduction of rats, pigs and dogs, which raid nests and compete with birds for food. Our research shows that many species have become extinct before written records began, leaving no trace and disappearing from history."
Dr Søren Formby of the University of Gothenburg, one of the study's co-authors, added: "These historic species extinctions have significant implications for the current biodiversity crisis."
"The world may not only be losing many fascinating birds, but also their various ecological roles, which are likely to include key functions such as seed dispersal and pollination. This will have a cascade of harmful effects on ecosystems, so in addition to the extinction of birds, we will also lose many of the plants and animals that depend on these species for their survival."
Observations and fossils show that 640 bird species have become extinct since the late Pleistocene, 90% of which occurred on inhabited islands. These include Mauritius's iconic bird, the dodo, the North Atlantic's great auk, and the lesser-known St. Helena's shearwater. But researchers estimate that 790 unknown species have gone extinct, meaning a total of 1,430 species have disappeared - with fewer than 11,000 species remaining today.
The scientists say their study reveals the largest human-driven vertebrate extinction event in history (14th century), with an estimated 570 bird species becoming extinct after humans first arrived in the eastern Pacific, including Hawaii and the Cook Islands, nearly 100 times the natural extinction rate.
They believe that another mass extinction event occurred in the ninth century BC, mainly due to the arrival of humans in the western Pacific, including Fiji and the Mariana Islands and the Canary Islands, and emphasized the ongoing extinction events that began in the mid-eighteenth century. Since then, birds have faced threats from anthropogenic factors such as climate change, intensive farming and pollution, in addition to increased deforestation and the spread of alien species.
The authors' previous research suggests that we could lose up to 700 new bird species over the next few hundred years, which would be an unprecedented scale of human-caused species extinction. But Dr Cook said "it's up to us whether more bird species go extinct. Recent conservation efforts have saved some species, and we must now step up efforts to protect birds, with local communities leading habitat restoration efforts."
The team created estimates based on what is known about bird extinctions and the extent of related research efforts in the region compared to New Zealand. New Zealand is believed to be the only place in the world where pre-human bird fauna is fully understood, and where all bird remains are well preserved. The less studied an area is, the less complete the fossil record is expected to be, and the greater the estimated number of undiscovered extinctions.
Compiled source: ScitechDaily