Road noise triggers aggressive shifts in island bird song, a new study suggests.

Galapagos yellow warblers show different behavioral responses to traffic noise depending on how close they live to roads.

Researchers from Anglia Ruskin University simulated intrusions into 38 bird territories on two islands – traffic-heavy Santa Cruz and quieter Floreana – playing bird songs with and without added traffic noise.

Warblers near roads became more aggressive when noise was added, while those farther away became less so.

Birds on both islands behaved similarly despite large differences in vehicle traffic, raising concerns about how even low levels of human infrastructure noise can ripple through wildlife populations in fragile ecosystems.

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