Newly published research has documented recent evolution in the beak and tarsus length of non-native Common Starlings in North America.
Common Starling is native to Eurasia but has been introduced to every continent except Antarctica, where it has proved an extremely successful adventive. In fact, in some areas, it has prospered so much that it is considered a pest, contrasting with the significant declines noted across parts of its native range.
Over the past 160 years, starlings have expanded into different environments throughout the world, making the species a powerful model for understanding rapid evolutionary change and adaptive plasticity. It was first introduced to North America in 1890, when approximately 100 birds were released at New York's Central Park.
Introduced Common Starlings in North America were found to have beaks an average of 8% longer than birds in the native range (Tom Moodie).
Studying more than 1,217 specimens, a team of researchers has shown that beak length in the native range of Common Starling has remained unchanged during the past 206 years, but that beak length in introduced North American birds is now 8% longer than birds from the native range. They also found that the average tarsus length has also decreased among North American starlings.
Drawing a comparison with the 2017 findings that UK Great Tits had evolved longer beaks than their continental European cousins as a result of exposure to bird feeders, the researchers suggest that large-scale cattle dairies and feedlots across the US may have driven starlings to evolve longer beaks to more efficiently forage in this highly modified, energy-rich agricultural landscape.
Reference
Zichello, J M, DeLiberto, S T, Holmes, P, Pierwola, A A, & Werner, S J. 2024. Recent beak evolution in North American starlings after invasion. DOI: https://doi.org/10.1038/s41598-023-49623-y
