Warning Issued for 80 Percent of Bird Species

A warning has been issued for 80 percent of the world's bird species, as many struggle in heavily human-dominated environments.

In a study published in Global Ecology and Biogeography, researchers at the University of Helsinki, Aarhus University (Denmark), the University of St. Andrews (U.K.) and the Mediterranean Institute for Advanced Studies (Spain) set out to find out how birds are affected by human-dominated habitats.

This is because 14 percent of the world's bird species are under threat. Most land animals, not just birds, have suffered from human-produced changes to their environments. While some species are able to adapt, many others are more vulnerable. Urbanization, air pollution and climate change are all factors that can alter habitats. The study reports that these can all have "myriad effects on ecological communities," such as habitat loss and fragmentation.

"Eighty percent of bird species can only exist in areas that are not under the most intense human pressures. Out of these species, many are endangered or have declining populations, but some are actually still doing fine and even increasing their population sizes," Emma-Liina Marjakangas, the study's leader, told Newsweek.

"However, in the future, the human pressures are predicted to intensify, which means that species that are still doing well today might decline or become endangered in the near future as their tolerances to human pressures are low," said Marjakangas, a postdoctoral researcher at the University of Helsinki and Aarhus University.

To reach their findings, the researchers assessed 6,000 bird species living in human-dominated environments, using data from the eBird project from 2013 to 2021.

Species that are most under threat are also less able to cope with the pressures of human-dominated environments. The researchers discovered that 22 percent of all bird species studied tolerated these environments. They also found that their tolerance for humans varied depending on their population. Species with declining populations have a much lower tolerance than those with stable or increasing numbers, the study reported.

"I wasn't surprised that so many bird species are struggling because the human impact on the planet is so pervasive," Marjakangas said. "Looking at the global human footprint map, there are very few areas that are both pristine and biodiverse—basically just the Amazon—which means that in most places birds simply have to exist under strong human pressures."

Marjakangas cited the fern wren as an example. This species lives only in the tropical forest of northeastern Australia. It has a rapidly declining population and finds it very hard to cope with human pressures, Marjakangas said.

"It's important to protect bird species because they are involved in many crucial functions in ecosystems," she said. "For example, birds act as dispersers of plant seeds, which ensures the regeneration of tropical forests. Birds are also very mobile and inhabit a great variety of different habitats, so protecting them means also protecting other species that occur in the same habitats."

In a statement, Marjakangas said: "Some species can tolerate even the most intense human pressures on all continents. Common swifts are an example of such species that can be found breeding in urban areas all around the world,"

A framework for the U.N. sets out goals to protect 20 percent of land on Earth for conservation, according to the study. However, it is not possible to leave all of this land as pristine, untouched habitat for birds.

In a statement, senior curator Aleksi Lehikoinen of the Finnish Museum of Natural History at the University of Helsinki said: "This study enables us to identify species that are particularly sensitive to human activity and need more protected habitats to thrive, for example the Great Snipe in Europe, the Nkulengu Rail in Africa and the Hume's Lark in Asia.

"Conservation action to protect or restore habitat can then be targeted towards the species and locations that need it most," Lehikoinen said.

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