Birds change their songs to be heard over the sound of automobile traffic, and when that doesn't work, they get aggressive. A new study in the journal Animal Behavior found that Yellow Warblers, which live throughout the archipelago, were impacted by human activity, even on a minimally populated island.
The Galapagos Islands, about 600 miles off the coast of Ecuador, are considered a living laboratory due to their unique species and geographic isolation. Charles Darwin's visit to the islands was the spark that led to his theory of evolution by natural selection. Yellow Warblers were studied on two of the islands: Santa Cruz, the main tourist hub, and Floreana, which has a population of less than a hundred people.
The study simulated an intruder, and on both islands, birds in close proximity to the road showed increased aggression despite the wide disparity in the amount of traffic. Birds on both islands increased the duration of their songs in response to simulated traffic noise, although more so on Santa Cruz, and birds on both islands increased the minimum frequency of their songs. Birds whose territory was one hundred meters away from a road decreased their aggression in response to the noise, indicating that regular exposure to traffic noise changes their behavior.
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