Last Saturday night, images of a snow leopard and other imperiled creatures lit up the 380-meter-tall Empire State Building to call attention to the animals’ plight. But the cats are no stranger to heights. Snow leopards (Panthera uncia) in the Himalayan mountains often prowl at elevations between 3500 and 5000 meters. How the spotted, gray felines survive in such low oxygen environments has puzzled scientists for years. That’s because all cats—from the house cat to the African lion—have hemoglobin that isn’t very good at carrying oxygen in the blood. The trait can potentially cause hypoxia or oxygen deficiencies in tissues and should lead the creatures to linger in relatively low-lying areas where oxygen is plentiful. But no one told the snow leopard. Thinking the animals might have evolved specialized hemoglobin that transport more oxygen than other cats, scientists worked with zoos in the United States to obtain blood samples from five big cat species—African lion, tiger, leopard, snow leopard, and jaguar. After conducting genetic analyses, they discovered that the hemoglobin genes of snow leopards look and work pretty much the same as those in other cats, they report today in The Journal of Experimental Biology. For now, it seems, the snow leopard’s high-altitude tolerance remains as enigmatic as the seldom spotted wild cats themselves.