Researchers: Starvation, weather to blame for bird die-off

December 4, 2020 GMT

SANTA FE, N.M. (AP) — Starvation and unexpected weather are to blame for a statewide die-off among migratory birds in New Mexico, researchers said Friday.

Biologists from multiple agencies collected hundreds of samples of warblers, swallows and other birds and sent them to the U.S. Geological Survey’s National Wildlife Health Center in Wisconsin to be analyzed.

The researchers found that nearly all the birds were severely emaciated, already starving when they moved into New Mexico. An unusual storm likely made things worse, they said, causing the birds to become disoriented and fly into buildings and objects. Some died from exposure to the cold weather, were killed by predators or hit by vehicles.


The evidence of starvation included kidney failure, empty stomachs, small amounts of blood, depleted fat deposits, irritated lung tissue and shrunken breast muscles that control the birds’ wings, the researchers said.

The researchers didn’t identify a single, definitive cause of death. They ruled out disease and poisoning.

Countless birds died earlier this year, with the first signs in late August. They were reported in the Taos area and at Valles Caldera National Preserve in the north to the cottonwood forest along the Rio Grande to southern New Mexico, including at White Sands Missile Range. Residents reported seeing them dying in groups, flying low and exhibiting lethargic and unusual behavior.

Large-scale birds deaths are rare, researchers at New Mexico State University have said.