This is a very good article on the pros and cons of wing clipping. This article is geared toward parrots but the information is still relevant to pigeons.
It's amazing how many people contact me and ask if they should be clipping thier pigeon's wings.
By Dr. Becker
The question of whether or not to clip a captive exotic bird's wings can be a difficult one.
If you own a pet bird or are considering getting one, it's important to understand both sides of the issue – the pros and cons of clipping (trimming) a bird's wings.
Creatures of the Air
Avian enthusiasts recognize birds are creatures of the air.
Exotic birds have home ranges of from one to five square kilometers, or from about a half square mile to about two square miles. A bird's home range is the area he lives and travels in – his territory.
In the wild, birds fly for necessity and for pleasure. Reasons for flight include:
To find food
To find other birds, including mates
To find parties (opportunities to socialize)
To find breeding and nesting sites
To escape danger and predation
Interestingly, while flying is instinctual for birds, landing isn't. Baby birds must learn how to land safely.
Birds bred and kept in captivity have the same instinctive urge to fly as their free counterparts. If allowed outside in open space unsupervised, your unclipped pet bird will fly away.
Some pet bird owners wrongly believe an unclipped tame bird will choose not to leave if given the choice. This just isn't true, and the vast majority of tame birds that fly away from home do not survive for long. Just a short time outside in winter temperatures, for example, can be fatal to a tropical bird.
Why Most Pet Birds Have Clipped Wings
Nearly all exotic birds entering the pet trade have their wings clipped very early in life. This teaches them in a roundabout way their wings don't work and not to rely on them.
Trimmed birds tend to be more docile than unclipped birds because they are unable to make independent choices about where they want to go and when. They are essentially captives to their perches.
Wing clipping is done primarily for safety reasons, though -- not to intentionally alter the attitude of the bird.
A clipped bird is far less likely to maim or kill herself by:
Flying into a wall during a fight-or-flight response
Landing on a hot surface in the kitchen like a pan of boiling water
Flying into a ceiling fan after being startled by a loud, unexpected noise
Gliding right out a door or window left open inadvertently
Flying into a closed window when, for instance, a tornado siren sounds
The goal of clipping is to reduce your pet's flight to no more than a downward glide. Proper trimming will dramatically reduce his ability to fly vertically or horizontally.
Wing Clipping Techniques
Wing clipping involves trimming your bird's primary flight feathers - the long, often brightly colored feathers at the ends of the wings.
There are several types of clipping techniques, including:
Standard Clip. This is the most common clipping technique. It involves cutting most or all of the primary feathers in half length-wise to the covert feathers.
Quill Clip. This is a newer clipping technique, compared to the the standard clip. Rather than cut the primary feathers in half, they are cut at the quill, beneath the coverts. The result is more attractive.
Supporters of this clip say it gets rid of the problem of sharp feather edges that may poke your bird and cause feather picking – a common problem with clipped birds.The downside to this clip is that heavy-bodied birds (such as macaws) have no "coasting" feathers and drop to the ground like rocks falling out of the sky, potentially damaging their keels (breastbones).
Show Clip. This technique leaves several of the end primary feathers untouched and is typically used to give the appearance the bird's wings haven't been clipped at all. This clip will limit but not eliminate your bird's ability to fly. It also carries risk of injury, such as ripped or broken feathers or a broken wing.
Every Other Feather Clip. This technique is rarely used by anyone with avian experience. Trimming every other feather leaves plenty of primary flight feathers. Most birds can fly with this clip, which eliminates its usefulness.
One Wing Clip. This is just a bad idea all around and I do not recommend it. Clipping the feathers on only one wing will certainly prevent your bird from flying, but it will also throw off her balance, increasing the likelihood she'll injure herself. The goal of clipping is to limit flying to a gentle downward glide. A bird with only one wing clipped will have problems gliding and especially, landing. This can result in injuries to the head, beak and breastbone.
I recommend you have a professional do the trimming, since cutting the secondary feathers or coverts by mistake can cause your bird balance problems and other health issues as well.
If you want to trim your bird's feathers yourself, you should learn the proper technique from an avian veterinarian or other avian professional before attempting it on your own. There are a number of risks associated with wing clipping, among them the possibility of cutting a blood feather, or causing an injury through improper toweling.
The most important reason, in my opinion, not to trim your bird’s wings yourself is that it can break trust in your relationship. Imagine, from your bird's perspective -- the person he loves most and depends on suddenly rolls him in a towel and does something that is very stressful to him. The result can be that your pet will become nervous around you, fearing the next time you come at him with a towel.
Let someone else be the bad guy.
Optimally, as a bird guardian, you have trained your baby bird to be toweled and to have her wings extended as a part of play, so when the actual trim happens, it's far less stressful for her.
If you do trim your own bird's wings and your bird finds it to be a stressful event, I recommend not speaking during the event and gently covering your bird's face. Once you're done, uncover him and tell him what a brave boy he was, rewarding him with his favorite treat.
Additional Benefits of Trimming
Aside from issues of safety, clipping will reduce your bird's opportunity to damage your furniture or leave droppings on surfaces like doors, walls, and window ledges.
A bird with untrimmed wings, unless he's potty trained or wearing a flight suit with a diaper insert, will decorate your home with colorful stains that can be hard to remove.
Some birds are easier to train if they can't take flight. If your pet is more dependent on you, bonding with her may take less time. Teaching her to repeat words or perform tricks often happens more readily with clipped birds.
Disadvantages of Wing Clipping
The most obvious drawback of trimming a bird's wings? It's a completely unnatural state of being for your creature of the air.
It's not as bad as, say, declawing a cat. Unlike declawing, which involves mutilating the front paws, a wing clip done correctly does not hurt the bird – it's the equivalent of a haircut. Declawing is done exclusively for the benefit of humans, not kitties, and can put a cat at risk if he ever needs to defend himself. Trimming a bird's wings, on the other hand, can provide a large measure of safety for your captive pet.
Flight is a natural form of exercise, which is important considering the rising trend of overweight pet birds.
It also provides a bird with the ability to escape a threatening situation. I no longer trim my birds' wings, though I have in the past. We've added a new, previously outdoor cat (that probably ate birds when he was a stray) to the family, and I want the birds able to take flight as their only form of defense if kitty decides to stalk them or pounce.
Another drawback to trimming is birds with clipped wings tend to feather pick more than other birds. Feather picking is an obsessive, destructive behavior birds engage in, in which they pull out, cut off, fray or otherwise do significant damage to their feather coats. Wild birds do not feather pick.
http://healthypets.mercola.com/sites/healthypets/archive/2011/01/27/wing-trimming-for-pet-birds.aspx