New research suggests that birds have a secret weapon that helps their internal compass.
In two studies, one published last week in the Journal of the Royal Society Interface and the other published in January in Current Biology, scientists have identified a special protein in birds' eyes that may help them to "see" the magnetic field of the Earth as they fly.
The protein, called Cry4, is found in the retina, Science News reported, and is part of a class of proteins that helps dictate circadian rhythms, or biological sleep patterns. Most of the proteins in that class fluctuate based on the time of day, allowing them to regulate the amount of rest the birds get. Cry4 is the only protein examined that is present in more or less the same amount no matter what time of day it is.
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Cry4 can also react to magnetic fields, thanks to quantum processes that occur on a microscopic level. "Birds use magnetic compasses any time of day or night" to find their way, said biologist Rachel Muheim, a co-author on one of the studies — so the fact that Cry4 doesn't fluctuate based on birds' sleeping habits is a big hint that it is the protein responsible for birds' ability to sense magnetic fields. In European robins specifically, Cry4 is present in even higher concentrations during the migratory season, ZME Science reported.
Despite the promising results of these studies, further research is required before the mystery of birds' homing instincts is solved. Read more about these new discoveries at Science News.
