In the wild, a duck with a broken wing may have difficulty surviving because of its vulnerability to predators and infection. Finding a duck with an injured wing could save its life, though it is important to handle the duck very carefully during any attempt to fix its wing, so as to avoid causing it further injury. You will need a means of transport to bring the duck to a safe and quiet place before fixing the wing.
Catch the duck and bring it to a safe place, where it is away from any other animals. Use a net if the duck won't allow you to approach it.
Check the wing to assess the injury. If it is broken, it should hang differently than the other wing and may be at an unnatural angle. The wing may even drag along the ground. If the duck is sick in any other way, take it to a veterinarian.
Search for open wounds on the wing. Wash any wounds in a weak iodine solution and administer antibiotics to the duck. Seek the help of a veterinarian to ensure the duck doesn't have an infection.
Position the duck's broken wing against its body in what would be the natural position. Wrap a strip of tape around the bird's body, around the outside of the broken wing and underneath the other wing, keeping the legs behind the tape. Don't wrap the tape too tight, as this will impede the duck's breathing.
Feed the duck good quality seed and water, using a shallow dish no more than 1/3 of an inch deep, immediately after fixing the wing. Hand-feed the duck if it is unable to eat on its own. If the duck refuses to eat, seek advice from a veterinarian.
Keep the duck in a small, confined area, such as a cage. Observe the bird to ensure it is eating well and that the tape is secure. Replace the tape at least weekly.
After two to four weeks, remove the tape, depending on how quickly the wing heals. When the wing has completely healed, take the duck to a larger area to let it try and fly. If the duck is able to fly well, you can release it to the wild, otherwise leave the duck with someone who can look after it.