They discovered that the reindeer had a 25% higher concentration of blood vessels in their noses, on average. They also put the reindeer on a treadmill and used infrared imaging to measure what parts of their bodies shed the most heat after exercise. The nose, along with the hind legs, reached temperatures as high as 75°F—relatively hot for a reindeer—indicating that one of the main functions of all this blood flow is to help regulate temperature, bringing large volumes of blood close to the surface when the animals are overheated, so its heat can radiate out into the air.

And you thought that red nose was a safety feature for low-flying aircraft…