How does a lone pigeon get back home? Does it choose the fastest, the easiest or the safest route?
As flying takes a lot of energy, birds generally adapt their flight speed and trajectory to reduce how much they use.
Now researchers at Swansea University have been using high-tech tags to study homing pigeons and to discover if these crucial decisions could be linked to helping them avoid attack by predators.
When the team monitored pigeons as they flew back to their loft at the Max Planck Institute of Animal Behaviour in Germany, they observed that the birds did sometimes adopt energy-efficient flight styles such as starting their climbs ahead of hills to reduce their climb angle. But they also saw pigeons using up energy by flying at high speeds.
He said: “This might suggest that pigeons are just trying to get home as fast a possible, but by comparing the variation in their flight speed and altitude to those of an ultralight aircraft following the same path, we found that pigeon altitude and speed was, in fact, very variable.
“Flying this way is neither efficient in terms of time nor energy, but it might have an unexpected advantage. Indeed, if we look at the trajectory of a rabbit on the run, or a snipe flying away, we can see that they make unpredictable sharp turns to confuse their predators.
“That is what we call a protean behaviour. Pigeons might be using the same strategy to increase their chances of avoiding an attack.
“Protean flight has only been described in a handful of birds up until now but we think that it might be a relatively common behaviour, with birds flying in a more unpredictable way when they fly solo.”
Co-author Professor Emily Shepard added: “When birds fly in flocks they achieve safety in numbers, but birds cannot fly in flocks all the time, for instance when they are breeding they make solo flights to and from the nest. That’s when strategies such as a variable flight style could come into play.”
Fine-scale changes in speed and altitude suggest protean movements in homing pigeon flights Baptiste Garde, Rory Wilson, Emmanouil Lempidakis, Luca Borger, Steven Portugal, Anders Hedenstrom, Giacomo Dell’Omo, Michael Quetting, Martin Wikelsi and Emily Shepard