Mass die-off of birds in south-western US 'caused by starvation'

Necropsy reveals 80% of the thousands of songbirds that died suddenly showed typical signs of emaciation

• Birds falling out of the sky' in mass die-off in south-western US
• Read more in our series Biodiversity: what happened next?

The mass die-off of thousands of songbirds in south-western US was caused by long-term starvation, made worse by unseasonably cold weather probably linked to the climate crisis, scientists have said.

Flycatchers, swallows and warblers were among the migratory birds falling out of the sky" in September, with carcasses found in New Mexico, Colorado, Texas, Arizona and Nebraska. A USGS National Wildlife Health Center necropsy has found 80% of specimens showed typical signs of starvation.