I'm not a scientist or researcher. I'm just a moderately intelligent guy who has been around pigeons my whole lift. The one question, anyone who encounters a fancier asks though is, "How do they find their way home?" This is my attempt to cover that subject. There are a lot of great people that have tried and are currently trying to answer that question. It's incredible that to this date, there is no one that has completely figured out how our birds find their way home. As a fancier and honestly, he can't tell you for sure. Most of us instead talk about the abilities of the birds that we do know of and say they must use a combination of those abilities. This section attempts to cover the subject.
So what do we know about our amazing pigeons? They can sense the magnetic poles of the Earth as well as magnetic fields. They use the sun as a compass based on it's position in the sky and the time of day. Pigeons can see polarized light. Pigeons can hear ultra low sound frequencies. Pigeons have such keen eyesight it is proposed they can see the stars during the day. Pigeons have a sense of smell that might even rival that of canines. A pigeon can fly 500-600+ miles in a day without rest covering well over 12 hours of flight.
Go onto the web, the library and any where else and eventually you will find research at various universities on the subject going back for years. Here are some examples that I have heard.
What's the common theme here? Attempt to throw a wrench in the works and get the engine to shut down.
The U.S. Navy had lofts on ships. The birds were able to home from one ship to another even at night. Mind you, at night with the right moon light and reflectivity from the water it's probably feasible. One conclusion was that each ship's engine had a distinct sound and the birds used the sound of the engine from their ship to find the correct ship.
Birds that were taken to a series of training points in a zig zag pattern when released at further points would fly over each of their previous release points even though they were not the direct route home. Soldiers were placed at each point when this observation was made.
The U.S. Army had mobile lofts. They were able to relocate the lofts and retain the birds by moving the lofts a few miles each day and letting the pigeons out to fly daily. When the loft was in the process of constantly moving the birds would not fly out of range of the loft. When the loft had become fixed for a period of time (I don't remember how long it took) the birds would eventually route further away and still home to their loft.
Now we are back to theories in our quest to answer this question. There are experiments in which various things have been used to restrict their natural abilities and their ability to orientate. But when someone asks that question it is usually a fancier trying o understand why there have been smash races on days with good weather. Why we have bad training tosses on what appeared to be a good day. There seems to be a consensus amongst homing pigeon fanciers that losses in young bird training and races both old and young birds are increasing. Theories and suggestions abound regarding why this is so. Here are some examples.
These are just some of many ideas. Surely there are some great research ideas in this list and maybe someone brilliant will explore them some day.
Bottom line is no one knows for sure what has been affecting our birds ability to navigate. We just know there have been more and more hard races and greater losses. We may not discover what the problem or combinations of problems are. I do know one thing. We have one wonderful tool at our disposal. Natural selection. The training basket, the racing crate and our own criteria are used to select pigeons that despite all these obstacles will find home. Through selective breeding as we already practice, we will breed through and around any obstacles. It doesn't matter if they ever find the answer. We keep training, racing and breeding in these ever evolving conditions and our birds will evolve around them as well.