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Virginie Rolland, Susan L. Balenger, Jennifer L. Grindstaff, and Lynn Siefferman: Read the article
Uri and Viola, two snowstorms in 2021, set new records of snow and subfreezing temperatures in southeastern US. Subsequently, people reported massive die-offs in wildlife, including among Eastern Bluebirds. So what allowed some of these bluebirds to survive?
As global warming reshapes our climate, it’s not just heat waves that demand our attention—harsher, more frequent winters are leaving their mark too. These extreme weather events are changing the way animals adapt and survive, including the Eastern Bluebird—a small, vibrant species found across Central and North America. Unlike its migratory populations who escape the chill, some year-round residents must face the cold at the onset of the critical breeding season.
What traits help these small birds survive winter’s wrath? And how might this shape their future generations? Dr. Rolland and colleagues tackled these questions, uncovering how extreme weather shapes survival and adaptation in this charming bird, and what that means for life in a changing climate.
For years, biologists have studied how animals adapt to their surroundings. But extreme weather throws a curveball: conditions far outside the norm can trigger sudden and unexpected changes. Dr. Rolland’s team explored this by tracking Eastern Bluebirds across multiple populations, examining traits like beak size, leg length, and feather coloration before and after a severe winter.
Their findings revealed a fascinating story of resilience. Birds that survived the harsh winter tended to have longer legs and bigger beaks—traits tied to larger body sizes, which likely helped them retain heat during freezing temperatures. They also had duller feathers, hinting that conserving energy early on, while more vibrant birds were busy attracting mates or finding nesting spots, gave them a crucial edge when food ran low, and the freezing cold hit hard. In the struggle against winter, it seems survival depends less on looking good and more on staying sturdy.
Interestingly, these traits may not be limited to surviving winter. The authors suggest that larger beaks and longer legs could also help with tolerating high temperatures during warmer months, hinting that these adaptations might persist long after the snow melts. This raises the possibility of lasting evolutionary shifts, where extreme weather pushes species to adapt in unexpected ways.
As extreme weather events become more frequent, this research highlights nature’s remarkable adaptability. Dr. Rolland’s study on Eastern Bluebirds demonstrates how species can rise to meet new challenges, offering a compelling glimpse into the future of biodiversity, raising important questions about the resilience of life in our rapidly changing world.
Baltazar González Chávez: Born in Colombia, I graduated as a biologist in 2015 in Cali, driven by a deep passion for evolution and biological change—a fascination nurtured by countless hours immersed in the brilliant writings of Stephen Jay Gould on the history of science. After several years working as a biologist, I moved to Argentina for postgraduate studies, spending six remarkable years exploring the Patagonian steppe and Andes. There, I focused on unraveling the evolutionary and biogeographic history of a rare group of Andean marsupials.
As my passion for biogeography deepened, I honed my skills in analyzing changes in species’ ecological niches across space and time. Currently, I am based at the Gaiarsa Lab at the University of California, Merced, where I use this expertise to study the effects of climate change on a wide variety of organisms, investigating its impacts at both regional and planetary scales.
