Pigeons Smell Their Way Home: Odors and Winds Reveal Location

Homing pigeons are some of the most successful navigators in the animal kingdom. They can travel for miles and still find their way back to their lofts. Exactly how they accomplish this feat, though, is still debated. Now, scientists have discovered that odors and winds may help these birds find their way home.

Over the past 40 years, scientists have conducted experiments on homing pigeons to find out about what systems they might use to navigate. Most interesting is the fact that these birds become disoriented when their sense of smell is impaired or when they don't have access to natural winds at their home sight. In order to investigate this phenomenon a bit further, the researchers decided to conduct a few experiments.

In a previous experiment, the researchers collected air samples at over 90 sites near a pigeon loft in Germany. The samples revealed that the ratios among certain "volatile organic compounds" in the atmosphere increase or decrease along specific durations. These changes in compound ratios translated into changes in perceived smell. Yet a pigeon that has never left is loft does not know in what directions these changes occur, unless it's been exposed to winds at its home site.

"If the percentage of compound A increases with southerly winds, a pigeon living in a loft in Wurzburg learns this wind-correlated increase," said Hans Wallraff, one of the researchers, in a news release. "If released at a site some 100 km south of home, the bird smells that the ratio of compound A is above what it is on average at its loft and flies north."

In order to test this idea, though, the researchers developed a model. This model revealed that "virtual pigeons" with only knowledge of winds and odors at home can find their way back to their lofts by using real atmospheric data.

"My virtual pigeons served as tools to select those volatile compounds whose spatial distributions, combined with variations dependent on wind direction, were most suitable for homeward navigation," said Wallraff in a news release.

The findings reveal the importance of smell when it comes to pigeon navigation. More specifically, it shows that smell could be one of the main ways that these birds manage to find their lofts from miles away.

The findings are published in the journal Biogeosciences.