s human-caused climate change continues to raise temperatures across the globe, understanding how birds regulate their temperature is vital for their conservation. But how much heat birds emit—an invisible spectrum of radiation known as mid-infrared—has never been studied, until now. Published in the journal Integrative Organismal Biology, a groundbreaking collaboration between material engineers and museum biologists explored the impact of mid-infrared on birds for the first time in history, reflecting the hidden prism of light, heat, and color in bird feathers.  

It’s long been known that habitat plays a role in bird coloration, a phenomenon described by biologists through things like Gloger’s rule, which predicts that animals like birds living in hot, humid areas will be visibly darker than those in dry, cool areas. Color is part of the electromagnetic spectrum, a visible wavelength that humans can see part of (the visible spectrum), and birds can see even more of (the ultraviolet spectrum), but heat, or infrared, exists outside the bounds of what either humans or birds can see. Infrared is broken down into the heat animals absorb (near-infrared) but not the heat they emit (mid-infrared). The interdisciplinary team of scientists measured both in the new study.