According to a recent study, humans have wiped out over 1,400 bird species, more than twice as many as previously thought, with significant consequences for the global biodiversity catastrophe. Many of the world’s islands were once virgin paradises, but the arrival of people in places like Hawaii, Tonga, and the Azores resulted in long-term consequences such as deforestation, overhunting, and the introduction of exotic species. As a result, many bird species were extinct.
While the extinction of many birds since the 1500s has been documented, our knowledge of the fate of species prior to this date is based on fossils, which are restricted because birds’ lightweight bones dissolve with time. This masks the full scale of global extinctions.
Researchers now believe 1,430 bird species — almost 12 per cent — have died out over modern human history, since the Late Pleistocene around 130,000 years ago, with the vast majority of them becoming extinct directly or indirectly due to human activity.
The study, led by the UK Centre for Ecology & Hydrology (UKCEH) and published in Nature Communications, used statistical modelling to estimate the undiscovered bird extinctions.
Our analysis shows that humans have had a significantly greater impact on avian diversity than previously thought. Humans have drastically depleted bird populations through habitat loss, overexploitation, and the introduction of rats, pigs, and dogs, all of which attacked bird nests and competed for food.
Dr Rob Cooke
Lead author Dr Rob Cooke, an ecological modeller at UKCEH, says: “Our analysis shows that humans have had a significantly greater impact on avian diversity than previously thought. Humans have drastically depleted bird populations through habitat loss, overexploitation, and the introduction of rats, pigs, and dogs, all of which attacked bird nests and competed for food. We demonstrate that numerous species fell extinct prior to written records, leaving no trace and so being lost to history.”
Dr. Søren Faurby of the University of Gothenburg, a co-author of the study, adds: “These historic extinctions have significant implications for the current biodiversity crisis.”
“The world may not only have lost many fascinating birds but also their varied ecological roles, which are likely to have included key functions such as seed dispersal and pollination. This will have had cascading harmful effects on ecosystems so, in addition to bird extinctions, we will have lost a lot of plants and animals that depended on these species for survival.”
Observations and fossils show 640 bird species have been driven extinct since the Late Pleistocene period — 90 per cent of these on islands inhabited by people. These range from the iconic Dodo of Mauritius to the Great Auk of the North Atlantic to the lesser-known Saint Helena Giant Hoopoe. But the researchers estimated there have been a further 790 unknown extinctions, meaning a total of 1,430 lost species — leaving just under 11,000 today.
According to the scientists, their research has revealed the largest human-caused vertebrate extinction event in history, which occurred in the 14th century. They estimate that 570 bird species were lost after people first arrived in the Eastern Pacific, including Hawaii and the Cook Islands, which is nearly 100 times the rate of natural extinction.
They believe there was also a huge extinction event in the ninth century BC, principally caused by the introduction of people to the Western Pacific, including Fiji, the Mariana Islands, and the Canary Islands, and emphasize the ongoing extinction event, which began in the mid-18th century. In addition to increased deforestation and the spread of exotic species, birds have faced additional human-caused dangers such as climate change, intensive agriculture, and pollution.
Previous research by the authors suggests we are at risk of losing up to 700 additional bird species in the next few hundred years, which would be an unprecedented human-driven decimation of species. But Dr Cooke points out: “Whether or not further bird species will go extinct is up to us. Recent conservation has saved some species and we must now increase efforts to protect birds, with habitat restoration led by local communities.”
The study team based its simulated estimations on known extinctions as well as the scope of relevant research in locations other than New Zealand. The country is the only area in the world where the pre-human bird fauna is thought to be totally known, with well-preserved bones of every species found. The less research conducted in a place, the more fragmentary the fossil record is predicted to be, as is the number of estimated undiscovered extinctions.
