Scientists suggest pigeons use their liver to find their way

Whether they’re rummaging through grass in a park or scuttling along pavements on the hunt for crumbs, pigeons seem to fit right in busy London. But the same bird that often blends in as part of the urban background has helped scientists investigate one of the hardest questions in biology. How can a pigeon be taken many kilometers from home and still find its way back? After all, unlike their human counterparts, they don't have the luxury of satellite GPS navigation. Animals use several techniques to navigate. Some follow the stars. Others remember landmarks, smells, or the position of the sun. Birds, fish, and sea turtles are also known to orient themselves using Earth’s magnetic field, effectively giving them a natural compass. That ability is known as magnetoreception. It means an animal can detect information from Earth’s magnetic field and use it for direction, position, and orientation. Since the 1960s, studies by researchers, including Cornell University ornithologist William Keeton, have shown that pigeons use several navigation cues at once. They can use the sun, familiar landmarks, smell, vision, and the Earth’s magnetic field. But scientists still haven’t fully understood how birds physically detect magnetism inside the body. Previous theories focused mainly on the eyes, the beak, and the inner ear. One idea suggested birds might “see” magnetic fields through light-sensitive molecules in the eye called cryptochromes. Now, a new study published in the journal Science points to the liver. Researchers from the University of Bonn, University Hospital Bonn, the University of Duisburg Essen, and the Max Planck Institute of Animal Behavior found that special immune cells in pigeon livers may respond to magnetic fields. Those cells are macrophages. In the pigeon liver, the researchers found macrophages packed with iron oxide nanoparticles. Those particles appear to make the cells superparamagnetic. In simple terms, superparamagnetic particles don’t stay permanently magnetic like a fridge magnet, but they react strongly when exposed to an outside magnetic field. This article was provided by The Associated Press.