The ‘Great Texas Freeze’ of 2021 wiped out up to a quarter of the state’s much-loved purple martin population, a study in Nature Ecology and Evolution has found. Now, conservationists worry it could take decades for the birds to recover, and fear for the repercussions of future extreme weather events.
For nine days in February 2021, two back-to-back deep freezes gripped the Gulf Coast, bringing record-low temperatures, ice and snow across Texas. Millions of homes lost power. More than 200 people died.
The weather was not kind to wildlife either and people were concerned for the purple martins, North America’s largest species of swallow. The migratory birds are one of the earliest arriving birds to the US Gulf Coast each year, typically appearing in January and February. To find out how they were faring, researchers harnessed the power of citizen science.
“The purple martin may be one of the most beloved and closely monitored backyard birds,” says Joe Siegrist from the Purple Martin Conservation Association (PMCA).
“When we recognised this unprecedented research opportunity, we were able to mobilise our army of martin lovers across Texas and Louisiana to increase monitoring of storm mortality and preserve samples for collection.
"Folks saddened by the loss of their birds were eager to turn this disaster into a contribution for the greater good of the species.”
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From their data, scientists from the University of Massachusetts, Amherst, discovered that the Great Texas Freeze killed thousands of adult purple martins at up to 52% of their monitored breeding sites. Those that survived then delayed their reproduction and went on to hatch fewer chicks the following spring.
Further knock on effects occurred in 2022, when the birds arrived at their breeding grounds two weeks later than normal. These martins were also genetically distinct to the birds that died the year before, and in some ways, were more like the martin populations that are found further north.
By 2023, the migration pattern had returned to normal, but with erratic weather patterns becoming more common, there are concerns about the birds’ long term adaptability to future climate change.
“People always ask me, ‘if you’re interested in climate change, why are you studying the cold?’” says Maria Stager from the University of Massachusetts. “But if birds are going to have a future, we need to know more about how they survive newly unpredictable conditions, which can include surprisingly cold temperatures.”
Top image: Experts are concerned about how purple martins will adapt to future climate change (pictured: Big Bend National Park, Texas) Credit: Matthew A. Barrett/Getty Images
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