Hummingbird feeders have become a significant evolutionary force for Anna’s hummingbirds in California. According to research published in Global Change Biology, these feeders have enabled the birds to expand their range from Southern California to the northern parts of the state. Over just a few generations, the birds’ beaks have changed significantly in size and shape.
Co-lead author Nicolas Alexandre, a geneticist at Colossal Biosciences, explains that Anna’s hummingbirds have adapted quickly to their new environments, similar to pigeons. The study utilized data from the Audubon Christmas Bird Count and newspaper ads to analyze the birds’ range expansion and feeder density. The findings suggest that while eucalyptus trees initially helped the birds expand, feeders played the most crucial role in their northward growth.
The researchers found that as feeders became more common, the hummingbirds’ beaks grew longer and larger, allowing them to consume more nectar. In colder regions, however, the birds developed shorter beaks to help conserve heat. Additionally, male hummingbirds in areas with dense feeders have developed pointier beaks, indicating increased aggressiveness due to competition over feeder control.
The rapid changes in Anna’s hummingbirds highlight the subtle ways humans influence evolution. The study’s findings offer a detailed explanation of the mechanisms driving the birds’ range expansion and adaptation, showcasing evolution in action.
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