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Researchers, biologists explore migratory bird deaths

Copyright © 2020 Albuquerque Journal

On a cool morning in mid-September, Melissa Moore stumbled across a dead songbird on the grounds of the New Mexico Wildlife Center in Española, where she is the executive director.

But she wasn’t surprised.

“This has been a new problem we’re having here,” she said, gently using a branch to remove the colorful bird from a walking trail. “I’ll have to have somebody come and get it tested.”

New Mexico and other Southwestern states were already recording large numbers of migratory bird deaths.

Now university researchers, the New Mexico Department of Game and Fish, citizen-scientists and bird enthusiasts are trying to determine why the deaths occurred.

Game and Fish biologists have collected more than 300 dead birds from across the state since Sept. 10.

The specimens will be sent to the U.S. Geological Survey National Wildlife Health Center in Wisconsin for complete necropsies.

“We chose the center because they’re known for thoroughness and work on bird mortality,” Game and Fish spokeswoman Tristanna Bickford said. “It could take a couple of weeks or a couple of months to get answers from them.”

Game and Fish biologists gave each bird a unique identification number, noting the species, date and location the bird was found.

“We also collect two tail feathers, which can be used for isotope analysis in the future,” Bickford said.

The research method can detect specific chemical elements to help reconstruct an animal’s diet or past climate conditions.

Jenna McCullough, a PhD student at the University of New Mexico and the Museum of Southwestern Biology, collected more than 300 dead birds in Velarde in Rio Arriba County on Sept. 14 with her colleague Nick Vinciguerra.

McCullough attributes the bird deaths to a cold snap during the height of migration season.

New Mexico had record high temperatures on Labor Day. Extreme winds the next day were followed by a day of plummeting temperatures and record early snowfall.

“Birds are exerting themselves to their max during migration,” McCullough said. “They have a very high metabolism and are sensitive to extreme changes in the weather. These migratory birds that stop to roost for the night, if they don’t have enough fat stores, they might die of hypothermia right then and there.”

Most of the dead birds the UNM researchers collected in Velarde and the Sandia mountains were swallows, which eat insects. Those bugs may have become dormant in the cold or covered by snow.

The UNM researchers collected the most birds from northern New Mexico, which saw the coldest temperatures earlier this month and recorded the most snowfall.

“If there’s no flying bugs, nothing to eat, and the birds are already stressed from migrating in the cold, they need to build up fat stores as soon as possible or they’re going to be affected,” McCullough said.

The birds from Velarde weighed about two-thirds as much as normal swallows.

McCullough cited several times in recent history when extreme cold and lack of food killed large groups of birds in Europe and Asia.

“I’m steeped in birds and bird death all the time, but it was still really upsetting for me to see this,” she said. “This die-off is bad, but it’s not species-ending extinction bad.”

Citizen-science efforts have also cataloged the recent bird deaths in several states. Nearly 800 observations for the “Southwest Avian Mortality Project” had been recorded on the iNaturalist website as of Friday.

The project was created by New Mexico State University graduate student Allison Salas. NMSU researchers are documenting recent bird deaths that occurred at White Sands Missile Range.

Bickford said Game and Fish is using the project to track the bird deaths recorded in New Mexico.

Game and Fish is working with several agencies to research the deaths, including the two universities, the U.S. Forest Service, Bureau of Land Management, Fish and Wildlife Service, Los Alamos Laboratory, Hawks Aloft, New Mexico Wildlife Center, Cottonwood Clinic, Audubon, Playa Lakes Joint Venture and Santa Fe County.

At the Museum of Southwestern Biology, the bird specimens will be part of a biochemical analysis study to determine their exact cause of death. Then they will be preserved in the museum for use in future research.

“I know that these birds didn’t die in vain,” McCullough said. “We collected them, and we’re going to learn something from them.”

Theresa Davis is a Report for America corps member covering water and the environment for the Albuquerque Journal.


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