Pigeons Homing Instinct

[snowy]

heres a good read, off a newsletter i recieve.

Pigeons wing it home on the sniff of a breeze

By Steve Connor

The mystery of how a homing pigeon is able to fly hundreds of kilometres to find its loft has been explained by scientists who have shown that the instinct relies on an acute sense of smell. A team of biologists found that young pigeons deprived of the chance of smelling the winds around their loft were never subsequently able to learn how to fly home. A study published this week in the Proceedings of the Royal Society of London revealed that an early ability to recognise the smells of local winds was crucial if a pigeon was ever to acquire its homing instincts. The first three months of a pigeon's life is crucial. Anna Gagliardo, the lead author of a team from the University of Pisa, said that learning to smell the wind allowed pigeons to associate odours with certain wind directions. "The outcome of this learning process is a map-like representation of the distribution of salient atmospheric odours in the region around the loft," said Gagliardo. The first three months of a pigeon's life is crucial. The researchers found that after three months of being kept in a screened aviary, deprived of wind, the pigeons never regained the homing instinct. Yet older birds, which had not been subjected to that sort of sensory deprivation, could relearn the homing instinct if they were moved to a new loft

 

[snowy]

http://www.racingpigeonforum.com/index.php?&start=75

 

[Guest]

Wondered what effect dark & light systems had on pigeons. Knew it must shift their biological clocks. Here's an experiment showing what happens to their homing instinct, but the editorial which follows the extract of the article explains things much more clearly:-

 

 

Factors reducing the expected deflection in initial orientation in clock-shifted homing pigeons  

 

 

 

Release date: 26 Jan 2005

 

 

 

To orient from familiar sites, homing pigeons can rely on both an olfactory map and visual familiar landmarks. The latter can in principle be used in two different ways: either within a topographical map exploited for piloting or in a so-called mosaic map associated with a compass bearing. One way to investigate the matter is to put the compass and the topographical information in conflict by releasing clock-shifted pigeons from familiar locations. Although the compass orientation is in general dominant over a piloting strategy, a stronger or weaker tendency to correct towards the home direction by clock-shifted pigeons released from very familiar sites has often been observed. To investigate which factors are involved in the reduction of the deviation due to clock-shift, we performed a series of releases with intact and anosmic pigeons from familiar sites in unshifted and clock-shifted conditions and a series of releases from the same sites with naive clock-shifted birds. Our data suggest that the following factors have a role in reducing deviation due to the clock-shift: familiarity with the release site, the lack of olfactory information and some unknown site-dependent features.

Anna Gagliardo, Francesca Odetti and Paolo Ioalè , J. Exp. Biol., 208, 469-478

 

An editorial comment on this paper follows:

 

Homing pigeons' uncanny ability to navigate home depends on a dazzling array of cues, including the sun, smells and familiar landmarks. Pigeons appear to use both a topographical map of familiar landmarks and an internal compass bearing to navigate across familiar terrain. To assess the relative importance of the map and compass, Anna Gagliardo and colleagues from the University of Pisa decided to see what would happen if the birds' map information conflicted with their compass bearing.

Pigeons use the sun as a compass, so to confuse the birds' orientation the team shifted pigeons' circadian rhythms by keeping the birds in an artificial light-dark cycle, resulting in clock-shifted pigeons. The birds' sun compass now indicated a wrong homeward direction but familiar landmarks could still indicate the true homeward direction. The team released normal and clock-shifted pigeons from familiar and unfamiliar sites and recorded the pigeons' orientation before they took off as well as the direction they disappeared in. At familiar release sites, the team saw that birds with normal circadian rhythms, which were able to use their sun compass, were homeward oriented even before take-off and flew off in the direction of home. But clock-shifted pigeons were randomly oriented before take-off and did not vanish in a homeward direction. Clearly, the sun compass strategy is important, but this was not the end of the story. Clock-shifted birds released from familiar sites showed a smaller deflection from the homeward orientation than clock-shifted birds released from unfamiliar sites. So while clock-shifting deflected the birds from the true direction of home, familiarity with the site reduced this deflection, presumably because the birds use familiar landmarks to ensure that they are homeward bound.

Yfke van Bergen