Humans may have caused the extinction of 1,430 species of birds

Reconstruction of the species Carduelis aurelioi. Image CC BY 2.4. Author: A. Bonner.
Reconstruction of the species Carduelis aurelioi. Image CC BY 2.4. Author: A. Bonner.

Humans could have caused the extinction of more than twice as many bird species as had been recorded until now, specifically 1,430 species. This data has been calculated using mathematical modelling and has been published in the journal Nature Communications in the paper Undiscovered bird extinctions obscure the true magnitude of human-driven extinction waves. It reveals the real magnitude of global extinctions caused by humans, with its implications for the current biodiversity crisis. Until now, observations and fossils showed that since the end of the Pleistocene (when humans began to expand around the world), about 600 species of birds have become extinct, 90% on islands inhabited by people. These species range from the iconic Mauritius Dodo to the North Atlantic Giant Auk and the seemingly lesser-known St. Helens Hoopoe. With this article and the statistical models developed, the researchers estimate that the real figure is slightly more than double: 1,430 species lost, approximately 11% of all bird species that currently exist.

These species range from the iconic Mauritius Dodo to the North Atlantic Giant Auk and the seemingly lesser-known St. Helens Hoopoe.

A few years ago, many of the world’s islands were oases of pristine nature, but the arrival of humans in remote places such as Hawaii, Tonga, the Azores and the Canary Islands caused far-reaching impacts that have lasted for many years.These include deforestation of the islands, over-hunting and the introduction of invasive species. Consequently, many bird species were wiped out in these island spaces. This disappearance of birds is documented from the 1500s onwards, because before then our knowledge about the fate of the species was only based on fossil remains, although there are still many sites to be discovered. Without fossils, the true magnitude of extinctions has remained unexplored and the knowledge we have is very uneven in different parts of the world.  

Now, a research team led by the UK Center for Ecology and Hydrology (UKCEH) –in which the research centre based in Barcelona CREAF has participated– has used statistical models to estimate how many undiscovered bird extinctions there might have been throughout modern human history (since the late Pleistocene about 130,000 years ago). The research team has used data from known extinctions and extrapolated how many more species might have gone extinct if the research effort was as great as it has been in New Zealand. This country is the only corner of the world where the pre-human bird fauna is believed to be fully documented, with well-preserved remains of all the birds that lived there.

“Despite the tragedy of losing species, there is still hope. Recent conservation actions have saved some species such as the Mauritius Kestrel, the California Condor. And we have the opportunity to intensify efforts to safeguard the habitats of many birds and avoid future extinctions in order to maintain the proper functioning of ecosystems”

FERRAN SANYOL, CREAF reseracher and co-author of the study.

Rob Cooke, UKCEH modelling specialist, notes “people have rapidly devastated bird populations through habitat degradation, overexploitation and the introduction of rats, pigs and dogs that prey on bird nests, on islands where predators have never existed before. Many species became extinct before written records were kept and left no trace”.

Three mass extinctions

Scientists say their study has revealed some of the most massive human-driven vertebrate extinction events in history. First, during the 14th century in the eastern Pacific (including the Hawaiian Islands), where it has been estimated that 570 bird species were lost after people first arrived, almost 100 times the natural extinction rate.

a Median bird extinction rate over the last ~7000 years. bd The spatial distribution of three major extinction waves. Three major extinction waves are labelled, and these are shown spatially in (bd). Point size represents bird extinctions and is scaled across the extinction waves. The top five regions are labelled for each wave. The maps are centred on 145°E longitude. Authorship: Birgit Lang, FJDegrange, Ferran Sayol, Francesco “Architetto” Rollandin, Juan Carlos Jerí, Mattia Menchetti, Peileppe, Rob Cooke, Sean McCann, Sharon Wegner-Larsen, and Steven Traver.

Secondly, in the ninth century BC, mainly driven by the BC, mainly driven by the arrival of people in the Western Pacific (including the Fiji Islands), and finally, the extinction event we are experiencing today, which began in the mid-18th century. Since then, in addition to increased deforestation and the spread of invasive species, birds have faced additional human-driven threats such as climate change, intensive agriculture and pollution. This ongoing crisis is expected to surpass the 14th century extinction event, as there is a risk of losing up to 700 additional bird species in the next few hundred years.

Ferran Sayol concludes that “these historical extinctions can have major consequences for the functioning of ecosystems. Not only has the world lost a large number of unique bird species, but the key functions that these birds performed will also have been lost. For example, the loss of seed dispersal or pollination has harmful knock-on effects on other species and the ecosystem as a whole”.

Reference:

Cooke, R., Sayol, F., Andermann, T. et al. Undiscovered bird extinctions obscure the true magnitude of human-driven extinction waves. Nat Commun 14, 8116 (2023). https://doi.org/10.1038/s41467-023-43445-2

This study relies on the participation of University of Gothenburg & Gothenburg Global Biodiversity Centre (Sweden), CREAF (Spain), Uppsala University (Sweden), University College London (UK), lInstitute of Zoology, Zoological Society of London (UK), University of Bayreuth (Germany), el Royal Botanic Gardens Kew (UK) and Oxford University (UK).

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