ALBUQUERQUE – Large numbers of migratory birds drop dead in New Mexico as scientists figure out what is causing one of the largest bird deaths in the Southwest in recent times.
After people began finding the dead birds in places ranging from hiking trails to suburban driveways to golf courses in the past few days, the mystery of what causes the death has increased.
Biologists are investigating whether the west coast forest fires could be a killing factor, with clouds of smoke potentially altering migration routes or increasing the toxins inhaled by birds.
“I’ve never seen anything like this in New Mexico lately,” said Martha Desmond, professor in the Department of Fish, Wildlife, and Conservation Ecology at New Mexico State University.
One of the first warnings about the death came on August 20, when a report described a sharp rise in the number of dead birds found in the White Sands Missile Range in southern New Mexico, said Dr. Desmond.
Since then, Dr. Desmond and other researchers published reports of dead migratory birds found in many parts of New Mexico, as well as parts of southern Colorado and western Texas. Dr. Desmond said the number of dead birds in the area could easily reach hundreds of thousands.
Trish Cutler, a wildlife biologist from the White Sands Missile Range, told Albuquerque TV station KOB over the weekend that fewer than half a dozen migratory birds would be reported dead at the weapons test site in a typical week.
“We had a few hundred in the last week, that really got our attention,” said Ms. Cutler.
Residents of different parts of New Mexico have been publishing increasingly similar reports in recent days. In a post on Twitter over the weekend, Austin Fisher, a freelance journalist based in northern New Mexico, recorded a video of dead birds he saw in Velarde while tubing on the Rio Grande.
“I was like, ‘Wait, I’ve never seen so many dead animals in one place in my life,'” said Mr. Fisher.
Jenna McCullough and Nicholas Vinciguerra, two graduate students in ornithology from the University of New Mexico, later surveyed the area and collected a total of 305 birds, including 258 purple-green swallows.
“Many of them have little to no fat, many are underweight, and there isn’t a lot of external evidence that they’ve inhaled a lot of smoke,” Ms. McCullough said.
Andrew Farnsworth, a senior research fellow at the Cornell Lab of Ornithology, noted that dieback began from the sharp drop in temperature in New Mexico last week. He added that the deaths “clearly represented a major event” for the broader problem of the killing of migratory birds, often by cats or from collisions with artificial structures.
“This year is different from other years,” said Dr. Farnsworth, adding that he believed the wildfires could be a potential trigger for bird deaths. “We have had many hot summers, but very few where these big fires were combined with heat and drought.”
Dr. Farnsworth said the particles or toxic compounds from smoke could be a major contributing factor. Pointing out migration patterns, he said researchers could find similar reports of dead birds even in northern Mexico and “as far as the Rocky Mountains.”
Many different types of birds have been found dead in New Mexico in the past few weeks, including warblers, swallows and flycatchers. Tristanna Bickford, a spokeswoman for the New Mexico Department of Game and Fish, said it would be some time before biologists can definitively determine what caused the death.
Ms. Bickford said officials from New Mexico provided specimens of the dead birds to the National Wildlife Health Center in Wisconsin for examination. She said it could potentially take months to diagnose the cause if a significant amount of testing was required.
“This is definitely not a normal thing,” said Ms. Bickford.
In the meantime, Ms. Bickford urged people who encounter sick or dead birds to proceed with caution. She recommended keeping cats indoors to add extra stress to migratory birds and urged people to wear gloves when collecting specimens of dead birds to hand over to wildlife and fish authorities.