Common guillemots are disproportionately vulnerable to oil spills due to their dense colonial aggregations and diving behaviour in shipping lanes.
Oil-soaked guillemots experience severe suffering through hypothermia as lost waterproofing exposes them to cold seawater, contamination of eyes and respiratory tract from oil inhalation, and starvation as diving ability is compromised. Rescued birds require intensive cleaning and rehabilitation over weeks. The stress of capture, cleaning, and captivity adds psychological suffering to physical harm. Many oiled birds die before or during rescue operations.