Guillemots are vulnerable seabirds forming densely packed cliff ledge colonies, particularly susceptible to oil spills that destroy feather insulation.
Oil coating causes rapid hypothermia as insulating air layer in feathers is destroyed. Oiled birds that reach shore suffer prolonged decline before death or rescue. Cleaning oiled birds is stressful and survival rates vary. Mass mortality events from oil spills can kill hundreds of thousands of birds at single colonies. Lead from sinkers and hooks ingested with fish causes neurological symptoms.