The griffon vulture, which ranges from Spain to India, has nothing but light down on its head and neck, no feathers at all on its legs and feet, and two bald patches on its chest. Until now, the only explanation for these bare spots was that they eliminated the problem of blood and viscera of carcasses from sticking to feathers. But Ofer Bahat, a zoologist at Tel Aviv University, has used a thermal imaging camera, which measures infrared radiation, to show that vultures use these naked patches for heat regulation. The camera revealed that the surface temperature of the bare-skinned areas is very high compared with areas covered with feathers, says Bahat. In the mornings the birds sunbathe, and on cold days they pull their necks in toward their body and cover their chest and feet with their wings. On hot days they stretch out and fly, exposing the bare- skinned patches in order to accelerate heat loss, says Bahat. Thermal images show that the surface temperatures of birds in flight are up to 5 degrees lower than those of vultures perching on the ground in the same area, as shown in these images, where yellow and orange are warmest, and blue and purple are cooler. Bahat’s research is part of a project to learn more about the endangered vulture and help prevent its extinction.