"For ecologists, the Covid-19 pandemic has presented a remarkable natural experiment in what can happen to wild animals when humans stay home."
"About two decades ago, the dark-eyed junco, a forest-dwelling sparrow, began to colonize urban Los Angeles. The birds proved to be remarkably successful in the city, making themselves at home on the bustling campus of the University of California, Los Angeles.
They also rapidly diverged from their wildland counterparts, adopting different breeding behaviors and displaying different physical traits, including shorter wings. The urban juncos also developed shorter, stubbier beaks, a shift that may have been driven by a change in diet.
But when U.C.L.A.’s campus shut down during the pandemic, something remarkable happened: The beaks of juncos born on campus reverted to their wildland shape. Several years later, after the pandemic-related restrictions had been lifted, the distinctive urban beak shape returned, researchers reported in a new study on Monday."
Emily Anthes reports for the New York Times December 15, 2025.
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