How Do Pigeons Find Their Way Home? Homing Explained

What is a homing pigeon?

A homing pigeon is a domestic breed of the rock pigeon, selected for centuries for speed, stamina and a strong urge to return to its loft. If you put one in a basket, drive it hundreds of kilometers away in an unfamiliar direction and let it go, it will usually fly straight home.

This is not migration. Homing pigeons return to one fixed point, their own loft, and they cannot be sent to a new address. That is why, in the days of pigeon post, birds had to be carried to the sender before a message could come back. Racing pigeons are trained by releasing young birds closer to home first and then at increasing distances.

The map and compass idea

To get home from somewhere new, a bird needs two things:

• A compass, to know which direction is which.
• A map, to work out where it is relative to home, and so which direction to fly.

German biologist Gustav Kramer proposed this “map and compass” idea in the 1950s after studying orientation in birds. The compass part is now fairly well understood. The map is the harder puzzle.

The sun compass

Pigeons use the position of the sun as their main compass on clear days. Because the sun moves across the sky, the bird must also know the time of day, and it does this with its internal body clock.

The classic test of this idea is the “clock-shift” experiment. Researchers keep pigeons for several days under artificial lights switched on and off six hours earlier or later than the real day. When released, these birds fly off about 90 degrees from the correct direction, the error you would expect if they read the sun with a clock that is six hours wrong. This shows clearly that the sun compass is a real and important cue.

The magnetic sense

In the 1970s American biologist William Keeton found that clock-shifted pigeons still oriented well on overcast days, suggesting a backup compass. When he glued small magnets to pigeons, the birds became disoriented on cloudy days but not on sunny ones. Later researchers, including Charles Walcott, showed that pigeons released at places with unusual local magnetic fields often scattered in random directions.

How pigeons sense magnetism is still not settled. Iron-rich cells in the upper beak were once thought to be magnetic sensors, but a 2012 study showed that they are immune cells, not nerve cells. Current research focuses on light-sensitive molecules called cryptochromes in the eye and on receptors linked to the inner ear and the trigeminal nerve.

Smell: an odor map

From the early 1970s, Italian scientist Floriano Papi and his colleagues, and later Hans Wallraff, carried out many experiments suggesting that pigeons use smell. Pigeons that could not smell were much worse at homing from unfamiliar places, while their compass orientation was unaffected.

The idea is that young pigeons sitting in their loft learn which smells arrive on winds from which directions. Released far away, a pigeon may recognize the mix of smells and work out roughly where it is. How precise such an odor map could be is still argued, and some researchers think smell may act more as a trigger for navigation than as a full map.

Landmarks and familiar routes

Close to home and on routes they know, pigeons also use what they see. In the 2000s, researchers in Oxford, England, and Zurich, Switzerland, fitted pigeons with tiny GPS loggers. The tracks showed that experienced birds often follow the same personal route home each time, tracing roads, railways, rivers and hedgerows, and sometimes turning at major junctions.

This means pigeons may navigate in two ways: using sun, magnetic and odor cues when they are far from home, and switching to remembered visual landmarks as they near familiar ground.

Low-frequency sound

Some scientists have suggested that pigeons can hear infrasound, very low-frequency sound below the range of human hearing, produced by ocean waves and wind over landscapes. A study by geophysicist Jon Hagstrum published in 2013 argued that unusual sound conditions could explain why pigeons released at some sites, such as Jersey Hill in New York State, often got lost. This idea is interesting but not widely accepted as a main explanation.

How good are homing pigeons?

Pigeons do not succeed every time. Poor weather, strong headwinds, birds of prey and magnetic storms have all been linked to failed races. Young birds on their first long flights are lost more often than experienced ones.

The ability to home made pigeons valuable to people for thousands of years. They carried news of sports results and battles, stock prices for early news agencies and, most famously, military messages in both world wars. Read about war pigeons to see how their skills were used.

Pigeons are not the only animals with impressive navigation. Many birds, sea turtles and even butterflies travel thousands of kilometers on regular journeys, described in our list of the longest animal migrations.