The loss of birds indicates a change in the planet

Billions of birds are disappearing due to humanity’s impact on Earth, global study finds

The world’s birds, described as the planet’s “coal mine canaries”, are disappearing in large numbers as humanity’s colossal impact on Earth increases, according to a global study.

There are about 11,000 species of birds in the world, but the populations of half of them are decreasing, while only 6% are increasing. Their flight and song make them easier to study than many animals, meaning they are the best-studied large group.

Bird populations are also affected by all the damage caused by human activity, from the destruction of wildlife habitat, the climate crisis and pesticides and other types of pollution, to overhunting and the impacts of alien species. and diseases. This makes them the best living indicators of global change, the scientists said.

Billions of birds have been lost in recent decades in North America and Europe alone, and although there are more species in the tropics, a greater proportion are threatened with extinction in the temperate and vastly wealthier countries, according to the revised study.

Conservation efforts have succeeded in saving individual species in specific places on the brink, but political will and funding are needed to reverse the global decline, the researchers said.

“Birds are much more powerful taxa [que otros] to tell us a story about the health of the planet,” said Alexander Lees of Manchester Metropolitan University, UK, who led the review. “We know so much about them that we don’t even know how many species of insects there are.”

“Currently we are assessing species at risk, but we are not stopping the flow of species towards extinction,” he said. “There’s not much we can do with site-based curation.” While conservation work has improved the populations of 70 species enough to reduce their risk of extinction since 1988, 391 species have deteriorated, according to the review.


the canary of the mine

Global data collected by Birdlife International supported the review and the conservation group’s chief executive, Patricia Zurita, said: “Birds are really the canary in the coal mine as indicators of the health of our planet. , given their sensitivity to changes in ecosystems, their ubiquity across the planet, and how well-studied they are. [Tenemos] We must listen and act on what the birds tell us, because they are disappearing faster and faster.

An exception to this broader decline is that of waterfowl, where populations living in wetlands in North America and Europe have increased by 13% since 1970. Restoring relatively small wetlands can have a large impact , while birds living in grasslands and forests need much larger areas.

The review, published in the Annual Review of Environment and Resources, found that 48% of bird species are known or suspected to be experiencing population declines, compared to 39% with stable trends, 6% showing increases and 7% with unknown trends.

Most long-term data comes from Europe, North America, India and some sites in Africa, but more recent monitoring in Latin America and Asia shows similar results. The bird population in the United States and Canada has been reduced by 3 billion since 1970, while 600 million have disappeared from Europe since 1980.

The review highlights the extraordinary variety of birds, from Antarctic petrels that nest 200 km inland from Antarctica to Hornby’s storm petrels that nest in the Atacama Desert. A Rüppell’s vulture flies at an altitude of 11,300 meters, while emperor penguins can dive more than 500 meters below the sea surface. The birds have great cultural value, but are also vital for ecosystems, including seed dispersal and pest consumption.

Birds are affected by all impacts of human activity

For example, an estimated 2.7 million people die each year in Canada alone from ingesting pesticides, while domestic cats can kill 2.4 billion in the United States. The bird families most at risk are those that are larger and take longer to breed, including parrots, cranes, and hardy birds like the Australian bush turkey. Every country is home to at least one globally threatened bird species and 10 nations have more than 75, according to the study.

Farmland species are in steep decline, according to the study, down 57% in Europe since 1980. This is due to intensive farming which provides cheap food, Lees said, adding: “If we want farmers to grow wildlife, we have to pay for that. as a society”.

Individual species have been saved, such as the Mauritius kestrel, which had been reduced to a single breeding female but has now revived a population of hundreds, and the Alagoas hocco in Brazil, which became extinct wild but has since been restored. birds. by private collectors.

But the review concluded: “The growing human population footprint is the primary driver of most threats to avian biodiversity. Lack of progress in conservation [de las aves] this usually reflects a lack of resources or political will, rather than a lack of knowledge about what needs to be done.

Professor Stuart Pimm, Duke University, USA, said the review was excellent and authoritative, even with low data availability in some regions. “What is certain is that about two-thirds of all bird species live in tropical forests, and human actions are reducing these habitats,” Pimm said. “Even without detailed population estimates, their numbers are surely declining.”

Lees said people shouldn’t feel powerless to help reverse the decline, but added: “We all have connections [con las aves]. If a company is associated with deforestation in Brazil, don’t buy anything from them,” he said. “And if everyone dedicates as much land as possible in their gardens to nature, that’s a pretty big area. Another lever is voting: we get the politicians we vote for.

By Damien Carrington. Articles in English

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