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Has anyone tried slapping a magnet on these migratory animals and testing whether or not they get hopelessly lost?

GuiA 10y ago
From the article: In the early nineteen-sixties, a German graduate student named Wolfgang Wiltschko began conducting experiments with European robins, which he thought might find their way by picking up radio waves that emanated from the stars. Instead, Wiltschko discovered that if he put the robins in cages equipped with a Helmholtz coil—a device for creating a uniform magnetic field—the birds would change their orientation when he switched the direction of north.
- shmageggy 10y ago
  It's been done more recently than that too. Here's one experiment with sea turtles: http://jeb.biologists.org/content/199/1/73 http://jeb.biologists.org/content/199/1/73
tgb 10y ago
Here's a great read about homing pigeons where they do that sort of test [1]. The answer appears to be that they use multiple cues so it's hard to isolate them. This seems likely to me, since there just doesn't seem to be enough information in knowing the magnetic field at your location to determine your home location, which the this article claims they do (they don't need information from the trip out to find home, and they fly roughly straight home so they must know the home direction immediately upon start). Interestingly, they can't return home if you knock out their sense of smell. But maybe that accidentally knocks out 'compass sense' as well. This article has some great snippits: "Older pigeons transported to the release site inside sealed metal containers, supplied with bottled air, anesthetized and placed on rotating turntables, all of which should make it hard for them to keep track of their outward journey, still home." They can home from 1800km away! And after being away for 7 years! They can home even if they never left the home loft (presumably until being sedated and carried away to test their homing ability), though the success rate is low. Edit: more directly to your question is this quote: "Keeton reasoned that if his pigeons were well oriented under overcast they must be using a cue other than the sun compass.He found that pigeons with magnets fastened on their backs were often disoriented when released under overcast." and "Under a sunny sky, the coils, whatever their polarity, only deﬂect the pigeon’s vanishing bearings by a few degrees. If a pigeon wearing an NUP coil starts its homeward journey under overcast, it will head away from the release point in the direction away from home. Should the sun appear, even if only momentarily, through a hole in the clouds, it will reverse course and head directly for home." [1] https://www.researchgate.net/publication/13905901_Pigeon_Homing_Observations_Experiments_and_Confusions https://www.researchgate.net/publication/13905901_Pigeon_Hom...
- david-given 10y ago
  You can teach yourself to see polarised light using the naked eye by exploiting polarisation effects in the lens of your eyeball. https://www.polarization.com/haidinger/haidinger.html https://www.polarization.com/haidinger/haidinger.html I've never seen this myself, however. Also, I don't know how useful this would be for direction finding. I can see that the effect would be useful for figuring out the direction of the sun on a cloudy day, but accounts indicate that the Haidinger's Brush effect is pretty small and easy to miss. But if humans can see it, more or less by accident, it's not much of a stretch to imagine than animals are much more sensitive to it.
Spooky23 10y ago
They have: http://blogs.discovermagazine.com/notrocketscience/2012/04/26/neurons-in-a-pigeons-brain-respond-to-magnetic-fields/ http://blogs.discovermagazine.com/notrocketscience/2012/04/2...

GuiA 10y ago

From the article: In the early nineteen-sixties, a German graduate student named Wolfgang Wiltschko began conducting experiments with European robins, which he thought might find their way by picking up radio waves that emanated from the stars. Instead, Wiltschko discovered that if he put the robins in cages equipped with a Helmholtz coil—a device for creating a uniform magnetic field—the birds would change their orientation when he switched the direction of north.

shmageggy 10y ago
It's been done more recently than that too. Here's one experiment with sea turtles: http://jeb.biologists.org/content/199/1/73 http://jeb.biologists.org/content/199/1/73

tgb 10y ago

Here's a great read about homing pigeons where they do that sort of test [1]. The answer appears to be that they use multiple cues so it's hard to isolate them. This seems likely to me, since there just doesn't seem to be enough information in knowing the magnetic field at your location to determine your home location, which the this article claims they do (they don't need information from the trip out to find home, and they fly roughly straight home so they must know the home direction immediately upon start). Interestingly, they can't return home if you knock out their sense of smell. But maybe that accidentally knocks out 'compass sense' as well. This article has some great snippits: "Older pigeons transported to the release site inside sealed metal containers, supplied with bottled air, anesthetized and placed on rotating turntables, all of which should make it hard for them to keep track of their outward journey, still home." They can home from 1800km away! And after being away for 7 years! They can home even if they never left the home loft (presumably until being sedated and carried away to test their homing ability), though the success rate is low. Edit: more directly to your question is this quote: "Keeton reasoned that if his pigeons were well oriented under overcast they must be using a cue other than the sun compass.He found that pigeons with magnets fastened on their backs were often disoriented when released under overcast." and "Under a sunny sky, the coils, whatever their polarity, only deﬂect the pigeon’s vanishing bearings by a few degrees. If a pigeon wearing an NUP coil starts its homeward journey under overcast, it will head away from the release point in the direction away from home. Should the sun appear, even if only momentarily, through a hole in the clouds, it will reverse course and head directly for home." [1] https://www.researchgate.net/publication/13905901_Pigeon_Homing_Observations_Experiments_and_Confusions https://www.researchgate.net/publication/13905901_Pigeon_Hom...

david-given 10y ago
You can teach yourself to see polarised light using the naked eye by exploiting polarisation effects in the lens of your eyeball. https://www.polarization.com/haidinger/haidinger.html https://www.polarization.com/haidinger/haidinger.html I've never seen this myself, however. Also, I don't know how useful this would be for direction finding. I can see that the effect would be useful for figuring out the direction of the sun on a cloudy day, but accounts indicate that the Haidinger's Brush effect is pretty small and easy to miss. But if humans can see it, more or less by accident, it's not much of a stretch to imagine than animals are much more sensitive to it.

Spooky23 10y ago

They have: http://blogs.discovermagazine.com/notrocketscience/2012/04/26/neurons-in-a-pigeons-brain-respond-to-magnetic-fields/ http://blogs.discovermagazine.com/notrocketscience/2012/04/2...