Hundreds of thousands of migrating birds are dying in southern New Mexico

Grace Reader
kob.com
Sun, 13 Sep 2020 13:23 UTC

A growing number of birds in southern New Mexico that have mysteriously died have wildlife experts scratching their heads.

"It appears to be an unprecedented and a very large number," said Martha Desmond, a professor at NMSU's Department of Fish, Wildlife and Conservation Ecology. "It's very difficult to put a finger on exactly what that number is, but I can say it would easily be in the hundreds of thousands of birds."

Desmond is working with a group of wildlife experts from the Bureau of Land Management, NMSU and White Sands Missile Range to get to the bottom of why they've been seeing a sudden uptick in deaths. They said one potential reason could be the cold snap that passed through the state last week.

"What is odd is the fact that we're seeing this occur beforehand and we're seeing it occur since then," Desmond said.

Environmental conditions like droughts could have also played a part in the deaths.

"It can be related to some of the drought conditions. It could also be related to the fires in the west. There may have been some damage to these birds in their lungs. It may have pushed them out early when they weren't ready to migrate," Desmond said.

Other researchers across the state are also exploring different theories because they said this phenomenon is not normal.

"On the missile range we might in a week find, get a report of less than half a dozen birds," said Trish Butler, a wildlife biologist at White Sands Missile Range. "This last week we've had a couple hundred, so that really got our attention."

People can help wildlife officials by reporting any groups of dead birds on the iNaturalist app.

"If people can, we would ask that they collect the birds, use gloves or a bag to pick it up," Desmond said. "We don't advocate touching the birds with their hands. Bag them, double bag them and put them in the freezer."

Comment: The Guardian reports:

Flycatchers, swallows and warblers are among the species "falling out of the sky" as part of a mass die-off across New Mexico, Colorado, Texas, Arizona and farther north into Nebraska, with growing concerns there could be hundreds of thousands dead already, said Martha Desmond, a professor in the biology department at New Mexico State University (NMSU). Many carcasses have little remaining fat reserves or muscle mass, with some appearing to have nose-dived into the ground mid-flight.

Historic wildfires across the western states of the US could mean they had to re-route their migration away from resource-rich coastal areas and move inland over the Chihuahuan desert, where food and water are scarce, essentially meaning they starved to death. "They're literally just feathers and bones," Allison Salas, a graduate student at NMSU who has been collecting carcasses, wrote in a Twitter thread about the die-off. "Almost as if they have been flying until they just couldn't fly any more."

The south-western states of the US have experienced extremely dry conditions - believed to be related to the climate crisis - meaning there could be fewer insects, the main food source for migrating birds. A cold snap locally between 9 and 10 September could have also worsened conditions for the birds.

Any of these weather events may have triggered birds to start their migration early, having not built up sufficient fat reserves. Another theory is that the smoke from the wildfires may have damaged their lungs. "It could be a combination of things. It could be something that's still completely unknown to us," said Salas.

"The fact that we're finding hundreds of these birds dying, just kind of falling out of the sky is extremely alarming ... The volume of carcasses that we have found has literally given me chills."

The first deaths were reported on 20 August on White Sands Missile Range in New Mexico. Initially, incidents were thought to be unrelated, but thanks to online forums, ornithologists noticed that they were happening all across the region. Resident bird species such as curve-billed thrashers, great-tailed grackles and white-winged doves do not appear to have been affected.

Large avian mortalities during migration are rare and few have been as large as this one. Records - which go back to the 1800s - show these events are always associated with extreme weather events such as a drop in temperature, snowstorm or hailstorm. The largest event on record in the region was a snowstorm in Minnesota and Iowa in March 1904 that killed 1.5 million birds.