Before attempting to restrain your bird ask your veterinarian or an experienced bird handler for a demonstration on the correct way to do it.  There are cautions you need to be aware of such as:  respiratory distress or death occurring if a bird is wrapped in a towel or cloth too tightly, his nasal passages can be blocked, or distress caused if he is kept on his back too long.  The Avian Restraint Jacket is the perfect accessory for temorarily restraining a bird for vet exams, grooming and post-anesthesia recovery.

Depending on the size of your bird there are different methods of restraining a bird in an safe and effective way ... for both the birds and yourself.  Once you restrain the bird you'll need someone to hold the bird so whatever procedure it requires can be accomplished without difficulty or stress.

Toweling a Bird
To restrain a bird an approriate-sized towel is necessary to wrap around the bird.  A small kitchen-type towel is appropriate for finches, budgies, cockatiels, etc.  A small hand towel is good size for smaller to medium-sized birds and a bath towel is good for the larger cockatoos and macaws.  With experience you'll decide if you'll need to alter of the size of the towel you've chosen.  Resizing some towels can cause fraying on the edges.  Be aware that nails can get caught on those edges so trim them as necessary.  To help your bird accept a toweling restraint procedure get the bird used to the towel by playing with him using the towel as a game.  Doing this well in advance of restraining the bird will help him overcome fear he may have.  I've used towels while playing hide and seek games with my birds and they've completely overcome their fear of them.  Don't use terry cloth towels on small birds because their nails can get caught in the loops of the fabric. 

If your bird is extremely shy, fragile or stresses easily try dimming the lights for a calming effect before attempting to restrain the bird with a towel. 

Toweling a Very Tame Bird
My birds are very tame and I've been able to use this approach very successfully for years. If you have a tame bird that is used to laying on his back and is comfortable with towels drape the towel over your lap, lay the bird on your lap and gently wrap the ends of the towel over him in a secure way that completely covers his wings and head.  Leave his tail free if it is long.  After you've restrained him in this manner you can slightly spred the towel away from his head so it isn't rubbing against his eyes. 

Toweling a Bird That's In His Cage
For birds that need to be restrained by approaching them in a cage, manuever the bird into a corner of the cage then drape the cloth gently over him.  While you need to be gentle, you also must move quickly if he has fear of the towel or you'll end up chasing him around the cage. 

For a bird that has been approached within his cage you'll need to control his head once he has been draped with the towel.  Hold the towel in place by placing your thumb and forefinger along the lower section of his beak or mandible.  An alternative way to secure him is to wrap your thumb and forefinger around his neck and apply slight pressure to the bottom edge of his mandible.  Once you've covered him with the cloth envelope his wings quickly with the trailing edge of the cloth and wrap the bird up in the towel leaving the bottom open for birds with long tails.  Lift the bird from his cage and rotate him so his underside is facing up.

After You've Restrained Your Bird
Cradle the bird in your hands or the crook of one arm, but try to keep the bird mostly vertical so he can breathe easily.  Let the bird grab the towel with his feet to feel more secure.

Restraining a Small Aviary Bird
If you need to restrain a small aviary bird use a bird net to catch him and then you can remove him from the net and restrain him in your hand or using a small lightweight cloth, securing his head as described above.

Another Tip and a Warning
Once the bird is restrained in the towel and held securely by one person, the other can proceed with an examination,  grooming procedure, or do whatever needs to be done.  If you are restraining your bird for wing or nail trimming remove one wing or foot from the cloth at a time, complete the trimming and then do the other wing and foot.

In restraining the bird use just enough pressure to keep him from escaping.  Excessive force can cause respiratory difficulty and damage feathers, skin and bones.