Rapid evolution in songbirds
Researchers at the University of California, Los Angeles (UCLA) have observed significant changes in the beak size of Dark-eyed juncos, a species typically not found in urban environments, as they adapt to city life, reports BritPanorama.
These birds, traditionally residing in mountain forests, have been increasingly spotted on the UCLA campus as climate change impacts their natural habitats. The adaptation to urban settings appears to have led to the development of shorter, stubbier beaks in city-dwelling individuals, unlike their mountain counterparts, which possess longer beaks suited for foraging seeds and insects.
However, a detailed study revealed an intriguing pattern: juncos born during the pandemic years of 2021 and 2022 exhibited longer beaks akin to those of their mountain relatives. This morphological shift suggests a response to changes in their environment, which reverted once students returned to campus and normal activity resumed, as evidenced in birds hatched in 2023 and 2024, according to researchers Pamela Yeh and Eleanor Diamant in a recent publication in the Proceedings of the National Academy of Sciences.
“We often think about evolution as a slow process,” said Diamant, now a visiting assistant professor at Bard College. “We thought that this would probably be too short of time to see a change in the population… So we were really surprised when we ran the data.” The stark year-by-year comparisons revealed rapid changes, which the researchers have linked to varying environmental pressures at the university.
The researchers hypothesize that shorter beaks are more advantageous for consuming human food scraps available in urban areas, particularly when dining facilities were closed during pandemic restrictions. As students returned, the pressures shifted back towards traits beneficial for traditional diets, leading to the shortened beak forms re-emerging.
This study underscores the rapid adaptability of wildlife to human-altered environments, highlighting how evolution can occur in response to transient factors such as changes in human activity. Yeh, who has been studying juncos for approximately three decades, emphasized the interconnectedness of human impacts and wildlife adaptability, suggesting there may be much more evolution occurring in areas we typically overlook.
“This research is unique, showing actual adaptive evolution associated with the pandemic with two significant phases linked to environmental conditions,” noted Jeff Podos, a behavioral ecologist who was not involved in the study. He pointed out that the findings stress the necessity of long-term research to capture these rapid changes in wildlife.
The study’s authors are currently working on genetic analyses to further clarify whether the observed changes in beak morphology are indeed genetically driven. Overall, the findings provide a more hopeful outlook on the resilience of certain species amidst the environmental challenges presented by urbanization and human activity.
“We’re causing a lot of harm on a global level,” Diamant said, referring to the global decline of junco populations. “But seeing how populations manage to keep up, despite what we view as these bad odds, I think brings a lot of hope that if they can do it, and it can surprise us, maybe other organisms can, too.”
As urban settings continue to evolve, understanding the adaptability and resilience of wildlife remains a critical area of research, first spotlighted by these findings on the Dark-eyed junco.
