How pigeons exploit magnetic fields for navigation

Iron-rich immune cells in the liver may act as sensors for magnetic fields, serving as an internal compass.

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[JohnDeL]

The process in the brain makes sense to me. It is right there, easily available, and reasonably sensitive.

The one in the liver looks like an ad hoc accidental adoption of something that was never supposed to be used that way.

Which, what with evolution being what it is, means that the liver is probably the real method and the brain is just a happy accident.

 

[JoHBE]

Great reminder of how limited our knowledge actually is. No doubt this has been extensively studied for many, many decades, and we still haven't figured it out. There must be millions of similar questions out there that we haven't even ASKED, because we don't even notice something special is going on.

 

[Rirere]

Let's use some of that mRNA tech in another recent article to inject our own liver cells with some of that potential pigeon homing insight and find out!

Though honestly in most of our current (smartphone-enabled) lives, the ability to always know which way is north or where we are relative to a specific point is less important than knowing what non-linear route of streets, paths, and other transportation channels will take us to our destination.

(given that pigeons obviously can just fly over obstacles, this clearly remains rather useful to them...)

 

[markgo]

Certainly brings a higher degree of accuracy to “gut feel”.

 

[CrystalCowboy]

I think the mag-field sensing cells need to be attached to some sort of structure. Take that cell in the top image: it could be telling the nerve: "the magnetic field is pointing away from the nerve cell." The nerve cell would be like, "dude, could you be more specific? I'm one-dimensional."

 

[Fatesrider]

There are three primary hypotheses for how birds might sense Earth’s geomagnetic field. One is a compass-like mechanism, whereby the Earth exerts a pull on magnetic particles in a bird’s upper beak that relays directional information via a large nerve in the cranium. A second is that it happens biologically via cellular ion channels sensitive to voltage, enabling birds to sense changes in the magnetic field. And a third suggests that physical effects on retinal pigments enable birds to detect photons and send signals to the brain, although this mechanism is really only viable in the light.

Why not all three? Nature does have a good sense of redundancy. And birds have been around a fuck-ton longer than anything else living today (except maybe some reptiles, since they came first).

There's no real reason to separate them, when the three different locations can POTENTIALLY be part of it. The size of the nerve in the cranium, though, suggests there's more going on there than elsewhere, since the liver always has iron in it and it's not really been often considered to be part of a sense of magnetic directionality.

Then there's this

For their homing pigeon study, Lisowski et al. used vibrating sample magnetometry and magnetic cell separation to test liver and spleen tissue samples stained with Prussian blue—which is sensitive to ferritin, a red blood cell degradation product—along with the eyes, beak, and brain. They found the strongest concentration of iron and the strongest magnetic response in the liver tissue.

Maybe it's just me, but this is where I think it fell apart.

The strongest magnetic response is NOT NECESSARILY the one the pigeon is using for magnetic navigation. But something that reduces the magnetic sense in a bird will not necessarily impact JUST the liver, and would, based on biology, hose it for everything.

So, IMHO, this proved nothing, other than birds do use magnetic sensing, probably iron, in their navigating that doesn't involve other clues like sun and even visual flying. The source of that sense is absolutely not determined by this study, because the thing that hosed the magnetic sense would hose it for any other iron-based sensory organs/methods the bird might have in the process.

 

[cbrubaker]

something, something... magnetism to find the bar...

I feel like there should be a joke there somewhere...

 

[moongoddess]

Why not all three? Nature does have a good sense of redundancy. And birds have been around a fuck-ton longer than anything else living today (except maybe some reptiles, since they came first).

Actually, both the dinosaur ancestors of modern birds and the earliest mammals both evolved n the Triassic. The earliest mammals predate true birds by over 100 million years.

But yes, a good amount of redundancy makes sense in any animal that has a large home range or which migrates, so I am not surprised that this study points to birds possibly having more than one way to sense magnetic fields.

And I'd never have thought of macrophages as playing a role as sensory cells, so this is exciting!

 

[Z1ggy]

Sorry, all i can think of when i think of birds navigating like this.
Good Ole Rescue Rangers

 

[CluelessOne]

So birds have a natural internal Magnetic Anomaly Detectors, and an Inertial Navigation System?

 

[dbtodd]

There was a Radio Lab episode that included a bit about the Jersey Hill Fire Tower that throws off homing pigeons. The episode is Lost & Found. Was fascinated then and now.

 

[Geburtenfresser]

Great reminder of how limited our knowledge actually is. No doubt this has been extensively studied for many, many decades, and we still haven't figured it out. There must be millions of similar questions out there that we haven't even ASKED, because we don't even notice something special is going on.

Preach!
Wonder how you are not getting negged in this community of almost omniscient apex beings.

 

[FranzJoseph]

There are three primary hypotheses for how birds might sense Earth’s geomagnetic field. One is a compass-like mechanism, whereby the Earth exerts a pull on magnetic particles in a bird’s upper beak that relays directional information via a large nerve in the cranium. A second is that it happens biologically via cellular ion channels sensitive to voltage, enabling birds to sense changes in the magnetic field. And a third suggests that physical effects on retinal pigments enable birds to detect photons and send signals to the brain, although this mechanism is really only viable in the light.

Why not both, as TFA notes?

The retinal quantum photon magnetic sensing seems to be more like just a compass, while the others could be sensing the more precise changes in the magnetic field like a local map?

 

[Jupitor13]

something, something... magnetism to find the bar...

I feel like there should be a joke there somewhere...

There pigeons walk into a magnetic field...

 

[i3en]

There was a Radio Lab episode that included a bit about the Jersey Hill Fire Tower that throws off homing pigeons. The episode is Lost & found. Was fascinated then and now.

Similarly, a Radiolab episode titled “Quantum Birds” covered aspects of this referencing the work of a team at Oxford, it’s a fun listen.

 

[Nora Lenderbee]

So it's maybe the liver and/or spleen? OK then.

The pigeon says "I think I'm headed in the right direction, but it's just a gut feeling".

 

[FelipeBG]

Nature is fascinating.

 

[TedDanzig]

There was an episode of Home Improvement where the neighbor (Wilson) imparted to Tim Allen the knowledge that certain animals are able to navigate using magnetic fields due to iron deposits in their nose.

I have no idea why I remember that as I wasn't a fan of the show, happened to see that episode 30 years ago, and do not have a very good memory in general.