Mystery ensues across New Mexico as hundreds of thousands of migratory birds have been found dead across the state in one of the Southwest's largest bird die-offs in recent memory. Scientists are examining the reason behind the alarming event, looking at possible factors such as the wildfires on the West Coast, the cold snap in the Mountain West, or the drought in the Southwest.
"It's just terrible," said Professor Martha Desmond from the New Mexico State University, noting that the figures are larger than ever seen before.
"The number is in the six figures. 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."
The mysterious deaths began around August 20, when a large number of dead birds were discovered at the U.S. Army White Sands Missile Range and White Sands National Monument.
Scientists initially believed that it was an isolated incident, but it turned out to be a bigger problem when hundreds more dead birds were seen in other regions across the state, including Doña Ana County, Jemez Pueblo, Roswell, and Socorro.
Residents reported seeing birds behaving unusually prior to their deaths. For instance, birds that are commonly seen in trees and shrubs have been found on the ground chasing bugs. Many birds appeared lethargic and unresponsive while on the ground until they get hit by cars.
Desmond, along with other biologists from White Sands Missile Range, started identifying, cataloging, and analyzing around 300 dead birds to learn more about their condition when they died.
Martha Desmond/New Mexico State University
Among the species of dead migratory birds found were warblers, sparrows, bluebirds, blackbirds, the western wood pewee, and flycatchers. Some were also found in Colorado, Texas, and Mexico.
One of the factors being considered by biologists is the wildfires on the West Coast, which may have forced the birds to migrate earlier. "Birds who migrated before they were ready because of the weather might have not had enough fat to survive," Desmond explained.
"Some birds might have not even had the reserves to start migrating so they died in place." She added, "We began seeing isolated mortalities in August, so something else has been going on aside the weather events and we don't know what it is. So that in itself is really troubling."
Some of the birds will be examined at the US Fish and Wildlife Service Forensics Laboratory in Oregon to identify their exact cause of death, but it would take some time to get the results. Desmond remarked that climate change played a role in mass deaths.
"This is devastating," she continued, "We lost three billion birds in the U.S. since 1970, and we've also seen a tremendous decline in insects, so an event like this is terrifying to these populations and it's devastating to see."
Image credit: Martha Desmond/New Mexico State University
Meanwhile, Jenna McCullough and Nicholas Vinciguerra, doctoral ornithology students from the University of New Mexico, surveyed the affected area and gathered a total of 305 birds, including 258 violet-green swallows.
"Many of them have little to no fat, many are underweight, and there’s not a lot of external signs that they have been inhaling a lot of smoke," said McCullough.
Dr. Andrew Farnsworth, a senior research associate at the Cornell Lab of Ornithology, noted that the deaths started before the sharp temperature drop in New Mexico last week, adding that the die-off amounted to a major event," in the wider problem of migratory birds being killed by other instances.
"It’s different this year than other years," he said, also noting that the wildfires could be a potential factor. "We’ve had plenty of hot summers but very few that have had these huge-scale fires combined with heat combined with drought."
USFWS and NM Game & Fish have been alerted. We at NMSU are working closely with them and other local wildlife biologist to understand the cause of this mass mortality. (2/9) pic.twitter.com/eg26PfejCQ— Allison Salas (@salasphorus) September 13, 2020
We have noticed that the majority of species collected are insectivores and long-distance migrants, such as swallows, wood-pewees, empidonax flycatchers, and warblers. (4/9) pic.twitter.com/dPoR1QFqtz— Allison Salas (@salasphorus) September 13, 2020
Tristanna Bickford, a spokeswoman for the New Mexico Department of Game and Fish, agreed that it would take time before biologists conclusively identify the reason for the die-off.
Some specimens will also be sent to the National Wildlife Health Center in Wisconsin for examination, where it would take months to diagnose the cause.
"This is definitely not a normal thing," stated Bickford, urging people to wear gloves if they collect specimens and hand them over to authorities.
Another interesting note is that resident species, such as Curve-billed Thrashers, White-winged Doves, and Great-tailed Grackles do not seem to be impacted at all. (6/9)— Allison Salas (@salasphorus) September 13, 2020
UPDATE (14 Sept 2020): Students from @nmsu_fwce 110 class surveyed campus for dead birds as part of their lab class today. In just a few hours they collected several individuals of different species. #SWAvianMortality #avian #conservative #migration pic.twitter.com/idvW2fAPZj— Allison Salas (@salasphorus) September 14, 2020
Featured image credit: Martha Desmond/New Mexico State University