Photo: Pexels/Hugo Herrera
Human activities have been wreaking havoc on the environment, destroying biodiversity from top to bottom, which is to say from apex predators like tigers to little insects. Birds have not been spared either and new research is raising the alarm about our feathered friends.
On once relatively remote islands like Hawaii, Tonga, Mauritius and the Azores human impacts, including deforestation, hunting and the introduction of invasive species, have resulted in the extinction of numerous bird species, the dodo being the most famous example, according to researchers.
“While the demise of many birds since the 1500s has been recorded, our knowledge of the fate of species before this relies on fossils, and these records are limited because birds’ lightweight bones disintegrate over time,” note scientists at the Centre for Ecology & Hydrology in the United Kingdom and the University of Gothenburg in Sweden. “This conceals the true extent of global extinctions.”
Based on their research the scientists postulate that as many as 1,430 bird species, or nearly 12% of avian species, have gone extinct since the Late Pleistocene around 130,000 years ago “with the vast majority of them becoming extinct directly or indirectly due to human activity.” This indicates, they say, that human impacts on avian diversity have been far more severe than previously assumed.
“Humans have rapidly devastated bird populations via habitat loss, overexploitation and the introduction of rats, pigs and dogs that raided nests of birds and competed with them for food. We show that many species became extinct before written records and left no trace, lost from history,” explains Rob Cooke, an ecological modeller at the British Institution who was a lead author of the study.
The effects of these human-induced extinctions on biodiversity have yet to be fully understood. They also present us with a clear warning about our adverse impacts on avian species. These impacts are worse than ever and now also include extreme pollution and climate change on top of habitat loss, hunting and invasive species introduced by people.
“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,” stresses Søren Faurby, a senior lecturer at the University of Gothenburg who was part of the research team.
“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,” Faurby adds.
The fossil record indicates that 640 bird species have been driven extinct since the Late Pleistocene period with 90% of these taking place on islands inhabited by people. These extinct birds include the great auk of the North Atlantic and the giant hoopoe on Saint Helena.
A further 790 unknown species are likely to have also died out, leaving today’s nearly 11,000 bird species, many of which are critically endangered.
This rate of extinction among birds is “the largest human-driven vertebrate extinction event in history,” the researchers say, adding that during the 14th century alone 570 bird species disappeared after people first arrived in the Eastern Pacific, including Hawaii and the Cook Islands. That is nearly 100 times the natural rate of extinction.
Another major extinction event took place in the 9th century BC, “primarily driven by the arrival of people to the Western Pacific, including Fiji and the Mariana Islands, as well as the Canary Islands, and highlight the ongoing extinction event, which started in the mid-18th century,” the experts argue.
“Since then, in addition to an increase in deforestation and spread of invasive species, birds have faced the additional human-driven threats of climate change, intensive agriculture and pollution,” they add.
Alarmingly we could lose another 700 bird species in the next few hundred years in another cataclysmic decimation of species. “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,” Cooke stresses.
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