Birds have built in magnetometer?

Nerves in the beaks of birds may not only serve as a "sixth sense" compass but are also magnetometers capable of measuring the intensity and inclination of the Earth's magnetic field. Researchers at the Goethe University Frankfurt previously studied iron-containing nerve branches in the beaks of homing pigeons. (Note that other scientists propose that cells in bird eyes, not the beaks, act as the primary compass.) Now, neurobiologists Dr. Gerta Fleissner Professor Günther Fleissner report similar structures in robins, garden warblers, and even domestic chickens. From a Goethe University press release (CC-licensed image from Wikipedia):

Specialized iron compounds in the dendrites locally amplify the Earth magnetic field and thus induce a primary receptor potential. Most probably each of these more than 500 dendrites encodes only one direction of the magnetic field. These manifold data are processed to the brain of the bird and here - recomposed - serve as a basis for a magnetic map, which facilitates the spatial orientation. Whether this magnetic map is consulted, strongly depends on the avian species and its current motivation to do so: migratory birds, for example, show magnetic orientation only during their migratory restlessness, as could be shown in multiple behavioural experiments by Prof. Wolfgang Wiltschko, who has discovered magnetic field guided navigation in birds. The cooperation with his research team has suggested that magnetic compass and magnetic map sense are based on different mechanisms and are localized at different sites: The magnetic compass resides in the eye, the magnetometer for the magnetic map lies in the beak.

"A magnetometer in the upper beak of birds?"

• [Karl Jones]

  Heaven help the birds if the Earth undergoes magnetic field reversal.

  Same again for animals having Ampullae of Lorenzini.

  • [PaulR]

    I have a suspicion that the sense’s base value are set quickly after birth or puberty, before they fledge. Much in the same way that some migratory bird imprint the star pattern/chart.

    Any reversal of Earth’s magnetic field would probably affect the adults rather than the year’s brood.

  • [Matt J]

    Since they have an inclination and intensity compass they’d be a bit confused for a while until they built a new magnetic map. The inclination and intensity of the Earth’s magnetic field change all the time, albeit not as dramatically as they would if the field reversed.

• [pjcamp]

  Magnetic boogers?

• [phisrow]

  I, for one, am glad to know that my EMP doomsday weapon will be of some use in both avian and robot invasions.

• [Tom Hale]

  People have this too – some kind of magnetic thing in their nose – seriously. Whether it really help them with directions I’m not sure – I read about it years ago.

  • [Nadreck]

    Adds new meaning to the phrase “just follow your nose!”

  • [Felton]

    Heh! I’ve always wondered why I have a good sense of direction. Maybe it’s because I’ve been blessed with a fairly large “magnet.”

  • [Matt J]

    People have this too – some kind of magnetic thing in their nose – seriously. Whether it really help them with directions I’m not sure – I read about it years ago.

    One study showed this. Many others have tried to repeat the results but failed.

• [justanotherusername]

  Why don’t they strap a powerful magnet to the birds head and find out if it can still get back home instead of speculating?

• [Tom Hale]

  What’s really weird, is I was just telling one of my sons about this about two hours ago. I finished saying, ‘I know that sounds like BS but it’s true.’

• [Gutierrez]

  Ah yes, the Bird. Nature’s iPhone Touch 3GS. With built in magnetometer, global position system, ability to deliver messages long distance, reproduce elaborate songs. Parrot models even have voice recording apps. And I hear the chicken models can play game apps like tic-tac-toe.

  Apple should be ashamed of ripping off nature so blatantly.

• [Matt J]

  As the quote says, we always knew some birds could sense magnetic direction. That they can sense inclination and intensity is somewhat more novel, but I’ve found a few studies which showed this a while ago. Sea turtles and some other animals have also been shown to have this ability in several studies. Theoretically, they can use this to identify where they are, but only in certain parts of the world where the gradient of magnetic intensity runs perpendicular to the gradient of inclination. Inclination varies approximately north-south (with the magnetic field being parallel to the Earth’s surface at the equator and perpendicular at the poles) whereas intensity varies somewhat more randomly. Yes, I did just write an essay on this!

• [SamSam]

  As an occasional archeologist, I look forward to the day when I can wander around a site with a chicken under my arm, and plot out a fairly good diagram of the underground walls by the sounds of its clucks. Those modern magnetometers are so clunky.

  @libelle: Are you sure that the research that you’re talking about is really about magnetometers (sensing variations in the directions of the fieldlines) and not just sensing magnetic North? The couple of articles I was able to pull up were on the latter. As others have said, we’ve known about North-seeking for a long time, but this magnetometer research sounds new.

  @justanotherusername: How do you know they did’t? For example, here’s an article on the effects of subjecting the birds to a magnetic pulse designed to scramble the magnetoreceptors (if I understood it correctly).

• [libelle]

  I’m surprised this is being published now. Back in the late ’70s and early ’80s, there were papers published on the topic. I’m not sure what this study brings which is new (except maybe the location of the magnetite in the beak, as opposed the the magnetite in the brain?)

  Look up Lowenstam, Weiner, Kirschvink, and Margulis for fascinating stuff on magnetite, like the fact that chitons have iron-plated, magnetic teeth.