Carrier Pigeon Illustration

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Research has been performed with the intention of discovering how pigeons, after being transported, can find their way back from distant places they have never visited before. Most researchers believe that homing ability is based on a "map and compass" model, with the compass feature allowing birds to orient and the map feature allowing birds to determine their location relative to a goal site (home loft). While the compass mechanism appears to rely on the sun, the map mechanism has been highly debated. Some researchers believe that the map mechanism relies on the ability of birds to detect the Earth's magnetic field. Birds can detect a magnetic field to help them find their way home. Scientific research has previously suggested that on top of a pigeon's beak large number of iron particles are found which remain aligned to north like a man-made compass, thus it acts as compass which helps pigeon in determining its home. A study led by Dr. David Kaeys now disproves this theory, putting the field back on course to search for an explanation as to how animals detect magnetic fields. The research, published in Nature, finds that "Previous studies claim to have identified a magnetic sense system in the pigeon, common to avian species, which consists of magnetite-containing trigeminal afferents located at six specific loci in the rostral subepidermis of the beak. These studies have been widely accepted in the field and heavily relied upon by both behavioural biologists and physicists. Here we show that clusters of iron-rich cells in the rostro-medial upper beak of the pigeon Columbia livia are macrophages, not magnetosensitive neurons (. . . ) Our conclusion that these cells are macrophages and not magnetosensitive neurons is supported by immunohistological studies showing co-localization with the antigen-presenting molecule major histocompatibility complex class II. Our work necessitates a renewed search for the true magnetite-dependent magnetoreceptor in birds. " Follow up research by Dr. Kaeys lab, published in 2019, moreover notes that "It is well established that an array of avian species sense the Earth's magnetic field and use this information for orientation and navigation. While the existence of a magnetic sense can no longer be disputed, the underlying cellular and biophysical basis remains unknown (. . . ) We find no evidence for extracellular magnetic otoconia or intracellular magnetite crystals, suggesting that if an inner ear magnetic sensor does exist it relies on a different biophysical mechanism".