Summary: Not all pigeons are homing pigeons, but all pigeons "home". Some pigeons are kept as pets, but feral pigeons are dirty and bothersome pests that can spread dangerous disease pathogens. The removal of unwanted pigeons is a difficult and time-consuming task, but it is possible.
Nothing is quite as unpleasant as leaving your car parked under a tree and returning to find it speckled with bird mess. What's even worse is leaving it parked on a city street and finding it peppered with pigeon droppings. The time spent cleaning it is wasted and that's the best case scenario. Worst case scenario is significant and costly damage to the vehicle.
Many pigeons fly wild, but not all. Raising and training homing pigeons is a popular hobby around the world. Pigeons have a remarkable ability to learn a routine, pattern or habit. They can watch a door long enough to know its timing for opening and closing, letting themselves into a building to roost. They can also imprint their "home" and find it whenever they are set free from another location. This homing ability has made them very useful at times. They've played key roles in wartime intelligence, relayed urgent information and provided hours of recreation for their owners. On the other hand, this homing ability also lets unwanted birds return to locations where they are not so welcomed.
Now, if these birds are so useful, why would anyone want to get rid of them? First, there is a big difference between kept birds and feral birds. It's the wild variety that causes the problems in our cities. They've been nicknamed "flying rats" and for good reason. Pigeon droppings are associated with disease organisms which may grow in and under bird droppings that cause histoplasmosis and cryptococcosis. They often carry lice, mites or other bugs, as well. Large flocks of feral pigeons can damage property and literally take over our streets and parks.
So how do you get rid of pigeons if you have an unwanted infestation? Rather than deal with the mess and risk disease, is there a way to relocate the pigeons? The first step is, of course, to prevent the birds from roosting in the first place. Posted signs are inefficient. Pigeons are notoriously illiterate and those that can read pay no attention to the rules. A much more effect method of control is to avoid feeding them. I can't think long about pigeons without that scene from "Mary Poppins" coming to mind: the little old lady on the park bench singing, "Feed the birds, tuppence a bag." Don't mimic that little old lady for it will only train the pigeons to treat your home as their home. Remember, water goes hand in hand with food. Your water sources may also provide an attraction for the birds. It may be necessary to remove that favorite bird bath or koi pond to deal with a pigeon infestation.
Once you've taken necessary steps to remove attractions, your second move is to try to remove the pigeons that have already taken a liking to you. Pigeons are creatures of habit and it may take a lot of patience and a combination of a number of removal techniques to get rid of them. Here are a few of the options you have to use against the birds.
Capture: You can buy pigeon traps and use them to, well, trap the birds. After you've caught them, then do what you like with them? You probably shouldn't release them elsewhere, unless that "elsewhere" is half-way around the world and a lot more pigeon-attractive than your home. It would take an eternity to re-train a dozen homing pigeons not to return to your pad. This method is greatly discouraged.
- Poison: This method is quite permanent. There's something a lot more likable about birds than about rats or roaches, so I'll understand if you dislike this idea. Also, in most places, poison baiting requires a license. Make sure you have all the necessary details for your location before pursuing this method. Plus, make sure you sound out your neighbors on this method. Otherwise, you may be faced with protestors outside your front door.
Sticky Gels: Sounds odd, but it helps. Pigeons really don't like walking through a layer of goo and gunk. You can purchase chemical gels that will annoy (and hopefully drive away) your pigeon pests. I might mention a little side problem with sticky gels. They collect the dirt particles that float in the air. After about six months all the sticky surfaces will be coated black and it is nearly impossible to get rid of the gel once you apply it.
Physical Barriers: These come in a wide range of forms. Nets, pigeon spikes, wire coils, electrical shock strips can all be installed at the actual roosting site to prevent birds from becoming too comfortable.
Of course, keep in mind that you are dealing with persistent birds. Pigeons that have claimed a site as their nesting area will not be easily deterred. In fact, nothing will work other than the netting.
If the task is too daunting, and it may be, contact a local exterminator with bird exclusion experience for more help. If you know a pigeon handler ask if he would be interested in removing your birds to retrain them to become part of his flock.