A distressing video recently posted to Twitter starts with a single bird dead next to a sunflower, and ends with more than a dozen dead birds strewn across a sandy ground in New Mexico.
They’re just a few of the hundreds of thousands of birds dropping dead during their migration across the southwestern United States.
Biologists who are struggling to find the exact reason why the migratory birds—which include warblers, bluebirds, sparrows, and blackbirds—are dying at such an astronomical rate.
Martha Desmond, a professor at New Mexico State University department of wildlife and conservation, told CNN the number of dead birds was staggering, and that they were acting strange and lethargic before their death.
"Just by looking at the scope of what we're seeing, we know this is a very large event, hundreds of thousands and maybe even millions of dead birds, and we're looking at the higher end of that," she said.
Besides New Mexico, the dead birds have been found in Colorado, Texas, and Arizona. The die-off doesn’t seem to be affecting species that reside in the southwestern states, only those that pass through them.
Desmond and other scientists tied their deaths to climate change and the wildfires ravaging the West Coast: The fires may have forced the birds to hit the skies for an earlier than usual migration, not giving them enough time to store the fat and energy needed to survive it.
Allison Salas, a New Mexico State University biologist helping study the deaths, tweeted she has been collecting dead birds “off the streets, on campus, at local golf courses, literally EVERYWHERE.” The birds seem to be in good condition, she said, “except that they are extremely emaciated.
“They have no fat reserves and barely any muscle mass, almost as if they have been flying until they just couldn’t fly anymore.”
Other scientists say the wildfire smoke could have caused lung damage to the birds, which may have led to their demise. The area has been suffering from a drought for years, which means fewer insects, which the birds feed on.
The University of New Mexico has started an online project in which local residents can post their observations and photos of dead birds to help researchers better understand the die-off. While it remains a mystery, Desmond told CNN she is sure of one thing:
“Climate change is playing a role in this.”
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