magnetic field

[Guest slugmonkey]

P.S.  GPS is now avaible to everyone a guy in our club has ordered one the chips are about 5 dollars each this will track birds right over computer

[Guest]

Slugmonkey, not sure which article and which subject you refer - birds brain sensing magnetic fields or birds eye seeing magnetic fields.  

 

Have been gathering navigation info for winter reading. Here are two 'mid-period' articles on magnetic fields... please remember that they are 20+ years old and perhaps old-hat now, as they are 'full' of maybe, could-be and possiblee.    

 

Alaska Science Forum September 28, 1979

 

Magnetic Navigation By Birds by T. Neil Davis

 

Article #345. This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. T. Neil Davis is a seismologist at the institute.

 

Careful tests with homing pigeons and other birds displaying the ability to judge direction show that the birds are affected by changing magnetic fields. Small coils placed near the birds' heads to create unnatural magnetic fields there do disturb the ability of pigeons to find home. Magnetic storms do the same. If birds are released at places where the earth's magnetic field is anomalously strong, their homing ability is entirely disrupted.

 

A possible reason why birds can sense the earth's magnetic field and perhaps use it for navigation is given by Charles Walcott and co-authors in the 7 September 1979 issue of Science magazine. Dissecting a number of pigeons, these scientists found the equivalent of a compass needle in each pigeon's head.

 

Next to, or essentially in, each pigeon skull, they located a tiny piece of tissue 1 mm by 2 mm (about 1/16 in by 1/8 in) that was somewhat magnetic. Searches inside this tissue with an electron microscope revealed the presence of more than ten million tiny crystals each four times as long as wide. Other tests demonstrated that these crystals were magnetite, the iron-oxygen compound of which compass needles are made.

 

As yet, it is not proven that the millions of minuscule magnetite "compass needles" in each homing pigeon's head are used for navigation, but it seems likely that they are.

 

These multiple compass needles are so tiny that they could readily oscillate in a rapidly-changing magnetic field such as might accompany electrical storms, earthquakes and also displays of northern lights.

 

So here also is a possible explanation of why birds sometimes seem to sense impending geophysical events.

 

 

Alaska Science Forum November 7, 1981

 

Bird Navigation by T. Neil Davis

 

Article #512

 

 

Experiments performed during recent years have strongly suggested that birds use the earth's magnetic field for navigation when they cannot see the sun or stars. The thought has been that when all else failed, the birds fell back to using the magnetic field to steer them. Now, a new experiment suggests that homing pigeons use the magnetic field as a preferred rather than a secondary guide.

 

Reporting in the October 16, 1981 issue of Science, German scientists described what happened when they released several different groups of pigeons on sunny days early in the morning. In one group were normally raised pigeons that had been exposed to the sun during all times of the day. When released, this group headed for home. The pigeons in a second group had never in their lives seen the sun before noon. They too flew for home without trouble, obviously using something other than the sun for guidance.

 

A third group of pigeons which also had not ever seen the forenoon sun but which had strong magnets glued to their backs were disoriented and flew off in random directions. They had neither the sun nor the earth's magnetic field to guide them, since the magnets they carried were strong enough to prevent the birds' sensing of the earth's magnetic field. Had these birds preferred to use the sun rather than the magnetic field, they should have flown in the direction opposite to home.

 

Thus this set of experiments, and other recent experiments of similar nature, seem to be pointing toward the idea that birds may be using the earth's magnetic field as a primary guidance source. They also use the sun and the stars, but these probably are secondary guides.

 

 

 

[Guest]

Just a thought on the first article.  ;D

 

If there's 10 million bits of magnetite already there, is there much point of trying to add more a-la-Bilco? And how would it get from the gut to the brain?  ??)

[Guest slugmonkey]

No it was the eye, the article stated that this part altered pressure in vessels in the eye and caused discomfort I was shocked to see this

[Guest]

I've skimmed an article which talked about birds and ultraviolet vision. The writer inferred evidence that seeing 'in ultraviolet' allowed the birds to see the earth's magnetic fields and the direction it was flowing in... and by implication, the bird could track it home. What he forgot to mention was that magnetic fields flow in two different directions, if I remember correctly South to North in the Western half of the globe, and North to South in the Eastern half, reversing every X years.

 

But certainly haven't come across anything about magnetic fields affecting bird's eyesight. Could you put up a summary of the eagle article, Slugmonkey?

[Guest slugmonkey]

I cant even remember where it was at I will do some research and see if I can't find it

[snowy]

last night early this morning,  half listening to radio 5 live i think,  there were a doctor on & some kind of professer/scientist i think, they were on about the earths core (magnetic field)  has moved dramaticly over the last couple of years, & the poles are moving like never before!

i was half asleep, but caught some of it, wish i had taped it! there were phone ins, & im sure this is what is upsetting the pigeons navigation by magnetic field.

anyone else catch it,?

was a scottish chap running the show.

regards

[Guest]

Didn't catch the programme, Snowy.  

 

Homing Instinct is a big issue for and a continuing puzzle to researchers. Been reading stuff lately, covering from 1950's to present day, and most agree with you that there is a 'magnetic field' element to homing. But most also agree that the bird just doesn't use one 'sense' to find home, it uses a mix of senses : magnetic field, sun as compass, hearing, sight, and smell. So if one 'sense' is missing or can't be used, they switch to another, or others in combination.

 

Those animals which have been proved to sense 'magnetic field' also have magnetite particles in their brains. These include pigeons, bees and humans. So there's proof of sorts that homing must be a mix of senses. If fluctuating magnetic fields, solar storms etc throw pigeons off track causing thousands to be lost every year, why doesn't it do the same to bees - migratory birds, and humans too for that matter?

 

The science also says the polls reverse every ? years. They've done this countless times before, and as far as I know (cause I wasn't here the last time it happened  ;D ) without impact on life on earth.

 

Incidently, the main reason I'm doing this reading ... I'd like to exercise the bird's mind as well as its body, by training & practice in the use of its homing instinct, get them to come home from anywhere in 'all' weather conditions?

 

 

[snowy]

agree totally bruno, it amazes me also that people & clubs only train & race in one direction, as early this year, took a bird on a few training flights with no problems, then one toss, less than a mile the opposite way, & lost! flew back to old owner!  obviously not training their brain,

[snowy]

also took 2 late late bred birds on a clear day a few weeks ago, for their first training toss,(should have never done it) (you learn by your mistakes) one cross janssen (sprint) been homing for about 4 weeks, & the other white logan, alot younger was still squeeking(stupid me) :-/  .only been homing round the loft for 2 weeks,

white logan returned almost straight away, janssen, never to be seen again,

[snowy]

the logan circled & circled wider & higher than the janssen & was still circling when the janssen shot off in the wrong direction, then after 5 mins of high circling (obviously using his brain) the logan headed straight for home!

a bad start to the story, but could be a good bird due to my mistake.

[Guest slugmonkey]

I found the article I am not sure as to origin it probably came from a link off of CBS or the Lou McElroy race I belive that the copy I have is a condensed version my wife typed as a cheat sheet I will put it up and try to find original

 

   SCIENTIFIC SIDE OF HOMING INSTINCT & EYESIGN

 

Inside the eyes are a series of tissues folded into pleats called PECTENS. Each pleat contains a fine network of LYMPH TUBES the lymph fluid in these tubes is ELECTROLYTE. That means it is affected by magnetic pull and operates as a conductor of electricity. When the eagle is young and the eyes are not fully developed these tubes are pliable they are affected by the magnetic pull of the North Pole very similiar to a compass. The PECTENS adjust themselves to the lines of magnetic intensity from the North Pole in relation to their place of birth. As the eaglet matures these PECTENS become more rigid and by the time the eaglet reaches maturity these are permanetly set

As long as the eagle is away from his nesting ground there is a sense of inbalance

These PECTENS are acting as a built in gyroscope causing pressure in the eagles eyes which in turn causes pain to some degree during migration . As he gets closer to his nesting ground the pain subsides. It is not difficult for the eagle to find his way home from thousands of miles away.

 

 

Again I belive this is a cheat sheet version and I will look farther

[snowy]

good reading though slugmonkey.

cheers

[Guest]

Thanks for searching out the article Slugmonkey.  

 

It makes interesting reading, but I fear its author has had a stab in the dark at what the pecten does ... and missed. Granted not much is known about it. Plenty research and theories abound ... supposedly 30 functions? But it doesn't have 'nerves' so any  theory that it is a sense organ is immediately suspect.

 

The avian retina doesn't have a blood supply, the pecten has (hence the 'electrolytes) and is thought to be involved in nourishing the retina. Wouldn't have thought electrolytes were magnetic, otherwise we would all be whizzing off towards the poles.  :B

 

The bit about the eagle in pain miles away from home is especially puzzling .. how does the youngster get away from the nest to set up home many miles away in a new territory? How do 'they' know its in pain? And especially that the pain is caused by internal pressure in its eyeballs? Did they burst?    ;D

 

In 'eyesign real or fake' thread, p2, post 41, you'll see the pecten in the diagram of the birds eye.

[Guest slugmonkey]

I have no idea as to the valadity of the article only relaying the message I am still trying to find the source

 

[Guest]

Think its good to keep articles and snippets coming, Slugmonkey, remembering always the person who posted them is just the messenger. I hope you do uncover more as I would be interested in the discussion section to see how the author(s) arrived at their conclusions.

 

Sincerely hope it doesn't include pics of popping eyeballs!!!! ... recently been through a few gruesome web papers, pics in full glorious technicolour , everything I didn't need to know ....  hopefully I won't come across the video ... now where's that sick bag??????                         ;D    ;D    ;D

[jimmy white]

looking back on these very interesting topics, i think that i would tend to agree with brunos first post,   that homing instinct be a mixture of senses, and the fitter the bird becomes the more sharper these senses are, but i think its a very difficult and complex topic.

[Guest slugmonkey]

I also agree with the two of you I dont belive that it is any one thing but a combination of factors and if we did know i think it would take a lot of the fun out

[Guest]

I dont belive that it is any one thing but a combination of factors and if we did know i think it would take a lot of the fun out

 

 

Just my opinion, one benefit of knowing at least the basics (and that is enough for me anyway) is that it may help steer us clear of specific merchants & theory gurus. For example, based on just one 'homing factor' -  the bird's ability to use earth's magnetic fields - magnetite is sold to be fed to pigeons as an aid to homing (Oh? where's the proof?); and some try to ram it down our throats as fact that magnetic storms in space affect our birds' homing capabilities here on earth - again without one shred of evidence.

 

[snowy]

thought this site be of help

http://www.harunyahya.com/articles/70pigeons.php