Experts believe starvation, weather caused bird deaths
Researchers with the U.S. Geological Survey National Wildlife Health Center pointed to cold weather and starvation as the likely cause of hundreds of migratory songbird deaths in early September across New Mexico, including Taos County.
The state Department of Game and Fish announced the findings, which seemed to corroborate a similar conclusion from researchers at the University of New Mexico who had said unusually cold weather blowing through the Rocky Mountains resulted in piles of dead birds.
Biologists from the state Department of Game and Fish in September sent carcasses to federal researchers to be analyzed. A lab report from the National Wildlife Health Center found evidence of starvation in nearly all the birds.
“The laboratory results are very informative but did not identify a single definitive cause of mortality,” Kerry Mower, a wildlife disease specialist for the Department of Game and Fish, said in a statement. “However, they did find that nearly all birds were [severely] emaciated.”
In birds sent for necropsy, biologists found shrunken breast muscles, kidney failure, empty stomaches and intestines, blood in intestines and depleted fat stores – all evidence of starvation.
According to a news release from the state Game and Fish Department, evidence indicates birds migrating through New Mexico likely were already starving when the entered the state, where they had trouble finding insects to eat after a cold front from Canada may have killed off prey.
“The unusual winter storm exacerbated conditions, likely causing birds to become disoriented and fly into objects and buildings,” the department added. “Some were struck by vehicles and many landed on the ground where cold temperatures, ice, snow and predators killed them.”
The deaths spurred alarm on social media when images of an unusual number of dead birds began circulating. Many wondered online whether cold, wildfires or climate change could be behind the mass deaths.
Independent of federal necropsies, University of New Mexico ornithology Ph.D. students Jenna McCullough and Nick Vinciguerra found 305 carcasses, which they took back to the university’s Museum of Southwestern Biology and found similar evidence of starvation: lack of fat stores, atrophied breast muscles and signs of dehydration as well.
Most of the birds the UNM researchers found were violetgreen swallows.
U.S. Forest Service Wildlife program leader Leslie Hay previously told The New Mexican that mass deaths have been seen in a wide range of bird species across the state. On the Southwest Avian Mortality Project, a website where the public can document dead birds, observers marked 150 species of birds found dead across the western United States and Mexico in late summer and September.