Massive Die Off of Birds in New Mexico … why?

Dead orange-crowned warbler (photo from Wikimedia Commons used as an illustration, not taken in New Mexico)

18 September 2020

In late August reports started trickling in that high numbers of migratory birds were being found dead in New Mexico. The first report was at White Sands Missile Range on 20 August but as time passed the reports became more frequent, the locations increased, and so did the death toll. By now experts believe that hundreds of thousands of birds have died — perhaps millions — not only in New Mexico (red on map below) but in Colorado, Arizona and western Texas (orange highlight on map).

General area of U.S. where massive bird die off is occurring (map from Wikimedia Commons). New Mexico is red

Austin Fisher took a video of the carnage last Sunday, 13 September 2020 in Velarde, New Mexico.

Science Alert reports that only migratory birds are affected, not the local residents. Most of the dead birds are warblers, swallows and flycatchers and “the affected travelers seem to act strangely before their deaths, spending more time on the ground than perched in trees, and generally appearing dazed, sleepy, and lethargic.”

Dr. Andrew Farnsworth at Cornell Lab of Ornithology believes the smoke from the western wildfires is a big factor.

While birds migrate south through the Rockies this fall they must fly through the ubiquitous wildfire smoke blowing across the US from California, Oregon and Washington. Here’s what it looked like via satellite on August 20, the first day dead birds were reported in New Mexico. Notice that the smoke had reached New Mexico that day.

Satellite image of wildfire smoke across the U.S. west, 20 August 2020 (image from NASA)

Unfortunately birds’ respiratory systems are so different from ours and so efficient that they succumb quickly to bad air.

We turn oxygen into CO2 in one breath — in/out. Every exhalation releases the CO2/remains of the air we just breathed in.

When birds breathe, the air that enters their bodies stays inside for two breaths — in/out + in/out. During its 4-step journey, the air molecule travels through the lungs, two sets of air sacs and into the birds’ hollow bones where it waits for the next step. Click on the diagram below to watch the airflow inside a bird.

Birds’ respiratory system, screenshot from animation at Oxford Learning Link

Sadly, the western fires are damaging much more than we realize. UPDATE 23 Sept 2020: a recent study found that the birds died of hypothermia and starvation. See: Explaining the recent mass mortality of western birds.

Read more about the bird die off at Science Alert and the New York Times.

(images from Wikimedia Commons, NASA and a screenshot from Oxford Learning Link. Click on the captions to see the originals)

5 thoughts on “Massive Die Off of Birds in New Mexico … why?

  1. Kate, you continue to educate and enlighten. I had no idea about birds’ respiratory systems. Thank you for this sad, timely post. I live in California and it’s devastating to see how far the smoke is traveling throughout the US and the world.

  2. Dear Kate , I just read about the birds dying on their migratory journey from the smoke caused by the wildfires. It makes me sad because all birds are beautiful and they are God’s furbabies now. I always say prayers every night for all the birds and butterflies and bees. These widfires have really devastated a lot of nature. I hope no more birds will die and I hope they get the wildfire put out.

  3. Thanks Kate for this startling news. I saw Jane Fonda talking about dead birds falling from the sky and now know what she was talking about. Too bad the climate change deniers can’t see this.

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