When it Comes to Bird Migration, Its All In The Nose

Everyone knows that birds migrate over great distances a few times a year, to follow the warm seasons. Sometimes, these migratory patterns take flocks of birds across the land and sometimes it takes them across the sea. The various species of birds who follow these migratory patterns rely on equally various combinations of senses to get them there; after all, they don’t have a map or navigation apps that can get them where they need to go.

Instead, birds use one of the oldest detecting methods around: the sense of smell. Indeed, new research shows that birds use their sense of smell to keep on course. As matter of fact, the new study helps to confirm some existing evidence that blocking a to a bird’s sense of smell is more disruptive to a bird’s navigating abilities than blocking their magnetic sensibilities.

But, that older evidence was somewhat incomplete. Cambridge University Oliver Padget explains: “Critics have questioned whether birds would behave in the same way had they not been artificially displaced, as well as arguing that rather than affecting a bird’s ability to navigate, sensory deprivation may in fact impair a related function, such as its motivation to return home or its ability to forage.”

Taking into account the existing studies, though, researchers managed to prove just how important the olfactory sense are to bird migration.
For the research, then, the scientists split the study population of birds into three groups. In the first group, the scientists disabled their sense of smell by exposing them to zinc sulphate. Scientists disabled the second group of birds magnetic senses using, obviously, a magnet. Finally, the scientists held the third group as a control. All birds wore GPS devices to track their movements.

The study found all three groups taking regular trips to forage for food and then return home with little or no disruption. This suggests that olfaction does not necessarily play a part in day-to-day avian behavior.
However, when they sent the group of birds without a sense of smell out over the open ocean, it took them longer than the control group to return. And when they did return, they tended to take unusual, inefficient, or even surprisingly direct routes.

All in all, animal behavior professor Tim Guilford comments, “To the best of our knowledge, this is the first study that follows free-ranging foraging trips in sensorily manipulated birds. “The displacement experiment has — rightly — been at the heart of bird navigation studies and has produced powerful findings on what birds are able to do in the absence of information collected on their outward journey.”

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