Report on the state of the world’s birds reveals a biodiversity crisis driven by intensive farming, with once-common species such as puffins and snowy owls now at risk

One in eight bird species are threatened with global extinction, and once widespread creatures such as the puffin, snowy owl and turtle dove are plummeting towards oblivion, according to the definitive study of global bird populations.

The State of the World’s Birds, a five-year compendium of population data from the best-studied group of animals on the planet, reveals a biodiversity crisis driven by the expansion and intensification of agriculture.

In all, 74% of 1,469 globally threatened birds are affected primarily by farming. Logging, invasive species and hunting are the other main threats.

“Each time we undertake this assessment we see slightly more species at risk of extinction – the situation is deteriorating and the trends are intensifying,” said Tris Allinson, senior global science officer for BirdLife International, which produced the report. “The species at risk of extinction were once on mountaintops or remote islands, such as the pink pigeon in Mauritius. Now we’re seeing once widespread and familiar species – European turtle doves, Atlantic puffins and kittiwakes – under threat of global extinction.”

According to the report, at least 40% of bird species worldwide are in decline, with researchers blaming human activity for the losses. After farming, logging is a key factor in declines of 50% of the most globally endangered species, followed by invasive species (39%), hunting and trapping (35%), climate change (33%) and residential and commercial development (28%). The illegal killing of birds – usually because of traditional hunting – results in an estimated 12 to 38 million individual birds dying or being taken each year in the Mediterranean region alone.

One victim of illegal hunting is the yellow-breasted bunting, which the report warns could repeat the cautionary tale of the passenger pigeon, once a common bird across North America before being rapidly driven to extinction in 1914. The yellow-breasted bunting was one of the most widespread birds across Europe and Asia but its population has declined by 90% since 1980 and its range has contracted by 5,000km. Although officially banned, large-scale hunting of this Chinese delicacy continues with the birds caught while roosting communally in reedbeds.

Overfishing and climate change is affecting seabird species, particularly the Atlantic puffin and the black-legged kittiwake, which are both now considered “vulnerable” on the International Union of Conservation of Nature (IUCN) Red List of imperilled species. The decline of the snowy owl is linked to climate change, with snowmelt in the Arctic affecting the availability of prey, while the European turtle dove’s rapid disappearance is caused by both hunting and habitat loss through modern farming.

Neonicotinoids – widely implicated in flying insect declines (a key bird food source) – have also been found to be directly detrimental to some bird species. One recent study from the US found that migrating white-crowned sparrows exposed to neonicotinoids lost a quarter of their body mass and fat stores. The neurotoxin also impaired the birds’ migratory orientation.

But there are conservation success stories: according to BirdLife, 25 bird species would have gone extinct this century without targeted conservation work, which has helped remove these species from the “critically endangered” list. The Guam rail, which is classified as extinct in the wild, has been successfully bred in captivity and returned to safe-haven islands cleared of the snake that predates it.

“Everything is reversible because everything is unfortunately of humankind’s making,” said Allinson. “It’s one thing to work at the last-minute on particular species and drag them back from the edge but what we do need is wide-scale solutions to agricultural intensification and expansion in particular – they are the biggest driver of extinction in birds.”

With bird declines also being driven by logging – 10 billion trees are being destroyed each year – one large-scale conservation response is the Trillion Trees project, in which BirdLife, the WWF and the Wildlife Conservation Society are combining to plant, protect and restore one trillion trees by 2050.

Allinson added: “We could easily feed the world’s population and leave room for birds and other wildlife if we were more sensible and reduced our food waste and pesticide use and put the right crops in the right areas. They are big challenges but there are successful systems that marry wildlife conservation and productive landscapes for people.”