When I was working at the University I met a fellow that was doing a study into a very small bird that migrated from Siberia every year to the shores of the Swan River in Western Australia, a distance in excess of ten thousand miles, they stayed a short while to breed then returned to Siberia for their summer, as scientists go he had to find out how they could navigate the extreme distance and arrive at exactly the same place at the same time each year, so what did he do he cut some of these poor little creatures into tiny pieces , one thing that he found was that there were small traces of magnetite in the brain tissue, this has since been confirmed by scientists from the Cornell University in America, when the time came for the birds to depart and head back to Siberia the amount of magnetite had built up considerably, so somewhere they had found a supply of the necessary mineral nearby to Crawley Bay on the Swan river, it could have been from the gravel and ironstone outcrops that were nearby in Kings Park or even the mineral sands near the beach, I asked my friend if he could get me a supply of magnetite so that I  could give to my birds to try, which he did, my results over the time that I used the magnetite proved to me that there was an advantage using magnetite as an additive to the birds diet to help their homing capability, since my first contact with magnetite I  have  found out that scientists have found traces of magnetite in the brain tissue of many migrating animals with some fish having traces in their nose.   

Now where to get magnetite it can be purchased as pure magnetite or if you live near any coalfields there should be plenty of magnetite available as it is used in the processing of coal, coal dust has magnetite in it, at one time I was talking to Peter Rigani a top English fancier and the conversation got around to birds homing to their lofts, he told me that his returns were not as they used to be, I asked him a few questions about what he may have changed in his birds diet, he said the only thing was he had stopped putting coal dust in with his grit, I advised him when he returned to England to go back to what he was doing, in a later correspondence he said that his returns had improved back to what they were before,

Titanium  (titano-magnetite) is another rich source of magnetite, one other thing that I found out is that the pigeons spend a lot of time picking on gravel paths or roads mainly to get the trace elements in the gravel, also included in the gravel is iron, my neighbors used to thing that I  was mad, and they were probably right as I  used to walk up and down the road dragging a magnet getting the iron for my birds, it  take long to get a small tin full, I  would feed this iron to the birds in their grit bowls, one other observation that I  made no matter how much the birds ate of the small particles of iron there was very little in their droppings it appeared that they had been able to break down the iron in their system somewhere, no matter where I went I had the magnet with me even on a trip to the beach, every time I had some minerals to bring home with me.

They are just opening a magnetite mine not far from where I live it is believed to be the biggest deposit known in the world.

The next step was to try the magnetite under racing conditions,

The Matthews bros from Arizona in America who were believers of the magnetite theory put the theory to the test, their conclusion was although that it was not a scientific experiment it appeared that magnetite does help the better bred birds nothing can help the poor quality birds.

The two brothers were the only ones to use magnetite in their club, they also gave several birds to other fanciers without telling them about the magnetite, they didn't mention it to the other members they wanted to see how their birds compared to the lofts not using magnetite, one flier in the club started with 200 birds and finished with nine, the other members in the club had teams near 100 birds and lost most of them, one of the brothers won most of the races the other won the 150 and the 300 mile race,  the 300 mile was won with two birds 30 minutes in front, the birds that they had given to other fanciers to fly that were raised on magnetite, were included in the prizes, all of the places in the hard 300 mile race were filled with birds that were raised on magnetite, and where all the other fliers had heavy losses the Matthews Brothers had 18 out of the 21 birds shipped to arrive home.

They found that it probably only helped the birds on bad days when the birds were split up or on smash races. 

Just to finish off this topic I have always earthed my loft roof to the ground, by running a wire to a star picket that I had driven into the ground, I was advised to do this many years ago by a fellow fancier, I do not know if it fits in with the Magnetic Grids or the magnetite all I know is that when there was a smash race there were few races that I did not home a bird and in some races I homed the only bird in race time

I have discovered today that it is highly magnetic, that is, drop a magnet near it and heaps will stick to the magnet.   To me that means that it contains large amounts of minute metal filings, ( similar to that you would find near a lathe in a engineering workshop - I wonder what the source of it is??)
If it contains actual metal filings, which is apparent, I question the birds ability to actually absorb metal filings into its bloodstream to maintain the iron level in the blood.   

I noticed that the birds tend to leave traces of it still in the bottom of the feed tray, - perhaps they don't appreciate chunks of steel in their breakfast?

Part 3

My 'layman's' reading, tells me that iron is essential in the blood stream to create red corpuscles, which in turn utilize the oxygen from the lungs, and we all know the importance of the oxygen to the birds performance.

As an alternative, a elderly retired flyer, told me that he used to buy from the local chemist a vitamin and iron tonic, labeled BCM.   He put a couple of cap full into the feed or water for three days before basketing and claims he had very good results.   His belief was the iron in the tonic.
I would reckon a human approved tonic like this BSM, in liquid form, would be more readily absorbed into the blood stream that actual 'metal filings'.

I have always wondered how pigeons found their way home, over the years I have tried several ways to find out, one was when I had a small radio transmitter made for me by a fellow at the University, every time I let the birds out I turned it on when I wanted them to trap,

My wife would turn it on the same time as I released the birds from short tosses, this went on for only a short time until the police knocked on the door and confiscated all my radio gear they said that I was using an illegal transmitter and was lucky that no charges would be laid.