The team then used infraredthermal scanners to record the bill's surface temperature while the bird was exposed to air ranging from 10 ° to 35 °C — temperatures typical of the toucan's habitat — and also while flying.
Just as visible light has a range of wavelengths (running from red to violet), so does infrared light: longer wavelength infrared waves are thermal, while short or near infrared waves are not hot at all, in fact, you can not even feel them.