Anthropause and Evolution in Urban Birds | 18 Dec 2025

Source: NYT 

The Covid-19 lockdowns created an “anthropause”, offering a rare natural experiment that revealed how reduced human activity can rapidly alter wildlife morphology, as seen in urban dark-eyed juncos. 

• Anthropause: It refers to the global, temporary slowdown of human activity, especially travel, during the Covid-19 pandemic lockdowns (early 2020). 
• Anthropause Effects on Wildlife: A study shows that dark-eyed juncos (a group of small, grayish new world sparrows) living in cities developed short, thick beaks because they fed on human food.  
  • During Covid-19 lockdowns, when people and food waste disappeared, birds born in 2021–22 developed longer, natural (wild-type) beaks.  
  • Once human activity returned, the urban beak shape reappeared, proving that human presence can drive rapid evolutionary changes in wildlife. 
• Similar pandemic impacts included quieter bird songs, closer wildlife movement to cities, and altered animal behaviour, reinforcing the concept of human-driven ecosystems. 
• The study supports the idea that evolution need not take millennia; under strong selective pressures such as urbanisation, evolutionary changes can occur within a few generations.