Navigation

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.

A prominent theory is that the birds are able to detect a magnetic field to help them find their way home. Scientific research 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. However, a 2012 study disproved this theory, putting the field back on course to search for an explanation as to how animals detect magnetic fields.

A light-mediated mechanism that involves the eyes and is lateralized has been examined somewhat, but developments have implicated the trigeminal nerve in magnetoception.   Research by Floriano Papi (Italy, early 1970s) and more recent work, largely by Hans Wallraff, suggest that pigeons also orient themselves using the spatial distribution of atmospheric odors, known as olfactory navigation.

Other research indicates that homing pigeons also navigate through visual landmarks by following familiar roads and other man-made features, making 90-degree turns and following habitual routes, much the same way that humans navigate.

Research by Jon Hagstrum of the US Geological Survey suggests that homing pigeons use low-frequency infrasound to navigate.   Sound waves as low 0.1 Hz have been observed to disrupt or redirect pigeon navigation. The pigeon ear, being far too small to interpret such a long wave, directs pigeons to fly in a circle when first taking air, in order to mentally map such long infrasound waves.

Various experiments suggest that different breeds of homing pigeons rely on different cues to different extents. Charles Walcott at Cornell University was able to demonstrate that while pigeons from one loft were confused by a magnetic anomaly in the Earth it had no effect on birds from another loft 1.6 km (1 mile) away.

GPS tracing studies indicate that gravitational anomalies may play a role as well.

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