The New York Times (paywalled) reported on Tuesday, December 16, the results of a study of dark eyed juncos around the campus of the University of California at Los Angeles.
Over the past few years, the juncos (part of the sparrow family) have adapted to living in LA and are now apparently enjoying human food. That changed during the Covid lock down when human activity was scarce.

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.

You can read the complete study Rapid morphological change in an urban bird due to COVID-19 restrictions from PNAS

The COVID-19 pandemic provided a natural experiment to test the impacts of human activity on urban-dwelling wildlife. Urban dark-eyed juncos differ in bill shape and size in Los Angeles in comparison to local wildlands. We measured juncos that hatched before, during, and after COVID-19 restrictions at a Los Angeles college campus. Birds that hatched during and soon after COVID-19 restrictions had bills that resembled those of local wildland birds. Yet, bills rapidly returned to pre-COVID-19 morphology in birds hatched in the years following pandemic restrictions. Thus, human activity (and lack thereof) underlies rapid morphological change in an urban bird.

So after reading the Times story, I looked out my deck, where there are juncos almost everyday and used my telephoto lens to zoom onto the large wildland birds’ beaks.

The weather ont the weekend was even worse. After the blizzard on December 13, December 14 was even worse with rain and freezing rain. So this distant shot of a junco on in the Kitimat River estuary was the only shot I got for this year’s Christmas Bird Count.