Bird's-Eye View May Include Magnetic Fields

BoredStiff writes "Heard on NPR and reported in ScienceDaily: a study finding that migratory birds may be able to 'see' magnetic fields. The report comes from a current study by a research group from Oldenburg, Germany. They found that migratory birds use their visual system to perceive the reference compass direction of the geomagnetic field: 'Sensory systems process their particular stimuli along specific brain circuits. Thus, the identification of what sensory system is active during magnetic compass orientation, provides a way to recognize the sensory quality utilized during that specific behavior.'"

Re:So what happens if the magnetic field changes?

[p0tat03]

Evolution. That's what happens :)

Does this mean birds aren't doomed after all?

[rde]

I'm a bit bemused by this whole concept, and the article doesn't really help ("Neuronal tracing reveals that Cluster N receives input through the thalamofugal visual pathway.")

Assuming the nerds in question are right (and I've not reason to think they're not), the whole 'seeing a geomagnetic field' thing is wrecking my head. We're all familiar with the shape of the Earth's magnetic field, and it's easy to envision a series of lines spreading out from the poles. However, given that the poles are due for a reversal, it's been assumed by people worldwide who know about such things that this means doom for most migratory birds. If they can see the field lines, though, this may not be the case. Rather, it's the time leading up to the reversal that'll be the problem, as the lines get ever more chaotic. Once the flip happens, presumably all will be well again.

Given that the poles have flipped many times in the past, and there've been major (if not mass) extinctions associated with at least some of them, the implication (to me) is that if there are fossils embedded in rocks with the polarity reversed then the two were simultaneous, and that some mechanism other than sight was used for sensing the fields.

Of course, this all assumes that a) I know what the hell I'm talking about, b) there's only one mechanism for detecting the field and c) the field looks the same from either pole.

So basically this article says...

[mpthompson]

... that migratory birds have a heads-up navigation display. Who would have thought?

Re:I thought we already knew this

[srmalloy]

Digging closer, however, the articles point to magnetic materials in otoliths, located in the birds' ears; the research referenced in the article is on how the input from the magnetic sensors is processed, not where the sensor is -- how the brain is wired to receive input from them, not merely their existence.

Re:Does this mean birds aren't doomed after all?

[EonBlueApocalypse]

I think if you were actually able to see the planets magnetic field that it wouldn't actually be represented in solid lines. I'd guess it would be hues of color where the field is strongest that are perceived, then anything else. I say this because what we see as color is just wave lengths of light being interpreted by our brains and I have yet to read anything that says vision and the colors involved can only be interpreted by the brain threw certain frequencies of light or sound. Anyways any species who has not evolved a back up plan like using the position of the sun, then some species may die out, but then again those aren't very successful if they a yet unable to cope with seemingly normal planetary changes.