Science | Animal magnetoreception
Migratory birds orient to Earth's magnetic field when blue-to-ultraviolet light stimulates a protein called cryptochrome 1a (Cry1a), present in the birds' retinal photoreceptor cone cells. Using an antibody that recognizes light-activated avian Cry1a, Nieβner et al. detected the mammalian homolog Cry1 in the blue light–sensitive cones of Carnivora families, including Canidae (dogs, wolves, and foxes), Mustelidae (badgers, otters, and ferrets), Ursidae (bears), and some primates (macaques and orangutans). Its location suggests that Cry1 does not regulate circadian rhythms or help animals perceive color. Whether Cry1 functions in a magnetic sense or whether mammals have different magnetoreception mechanisms remains unclear.