Why can oil-coated birds die from hypothermia after an oil spill?

Oil-coated birds are highly susceptible to hypothermia because the oil disrupts the natural structure and function of their feathers, which are essential for maintaining body temperature.1

Under normal conditions, a bird’s feathers provide critical insulation by trapping air against the skin, creating a protective barrier against cold temperatures and water. When a bird becomes coated in oil, this protective layer is compromised; the oil mats the feathers together, destroying their ability to trap air and allowing cold water or air to reach the skin directly.21

Because birds are homeothermic—meaning they must maintain a stable internal body temperature—the loss of this insulating barrier forces them to expend significant amounts of energy to generate heat through metabolic processes. When they can no longer maintain this balance, they succumb to hypothermia. Furthermore, as birds attempt to clean themselves, they often ingest the toxic oil, which can lead to additional health complications and further weaken their ability to survive the environmental stress caused by the spill.31