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Hundreds of Thousands of Birds Are Suddenly Dropping Dead. No One Knows Why.

Photo credit: Fernando Trabanco Fotografía - Getty Images
Photo credit: Fernando Trabanco Fotografía - Getty Images

From Popular Mechanics

  • Scientists have found thousands of dead birds representing an estimated die-off of hundreds of thousands or more.

  • Birds are often canaries in the coal mine for extreme weather and overall climate change effects.

  • These birds seem like they're starving, sluggish, and disoriented, which could be environmental in several ways.


An alarming “mass die-off” of wild birds in the southwestern U.S. has scientists worried—and perplexed. The cause is not at all clear, with some scientists theorizing that climate change factors are playing a part. Most of the birds are insect eaters, and they’ve been found emaciated and disoriented, suggesting a gap in the food supply. There’s also speculation that wildfires are affecting the lives of these birds.

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CNN reports on the dark phenomenon and firsthand accounts of the sick and dying birds. The observations sound like what you’d expect from animals with a contagious, behavior-changing disease like rabies. “On the [White Sands] missile range golf course [in New Mexico], swallows, which are aerial insectivores that don't even walk, were sitting on the ground and letting people approach them,” CNN explains.

That’s frightening to even imagine. Other birds were too slow to avoid oncoming cars. Local scientists estimate that hundreds of thousands of birds are affected already, and that number could potentially reach millions.

On Monday, ecologist Martha Desmond, a professor in New Mexico State University’s department of fish, wildlife, and conservation ecology, told CNN, “Climate charge is playing a role in this.” But Tuesday, Desmond told the NPR show Here and Now, “The scientist in me will say at this point we really don’t know.” She explained:

“This is migratory season, and birds move in pulses with large weather events, and we saw a large number of birds come south to this region at that time. It’s unusual, but we do see die-offs of birds in the spring and in the fall with weather events. Usually it’s a one-pulse event such as hail or a snowstorm.”

But in those (rare) die-offs, there are hundreds or maybe thousands of dead birds—not hundreds of thousands.

So what could be happening? There are a number of potential factors that all make an intuitive sense. Migratory birds already walk a fine line as they decide when to migrate and what route to take. They sense weather patterns and seasonal changes and are drawn to fly south. That’s why fluke weather events can disrupt migration in multiple ways.

Think about how a plant might bloom during an early spring thaw and then be frozen when seasonal weather resumes. If it’s a vegetable plant or fruit tree, that first freeze might impact the entire year’s harvest. Now think about the Donner party (really), a group of settlers who had to make a decision about whether to push farther before they’d be snowed into a dangerous mountain pass. Between extreme weather and the subsequent reliance on an unseasonal or uncharacteristic food supply along the way, birds might be jammed between both examples.

A team at White Sands first noticed the die-off, and Desmond told CNN and WBUR that she first believed the incident was isolated there, not because of any factors at the infamous missile range itself, but just because of the usual scale of these bird death events.

From there, scientists began noticing other dead birds elsewhere in New Mexico and even states away. We likely won’t understand the full scope and range of causes for years.


🦅 Great Binoculars for Bird Watching

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