Angel wing is a condition that causes a bird's wing to not grow properly and twist, leaving them unable to fly. (Tim Jasinski/Lake Erie Nature & Science Center)

People in Ottawa are being asked to stop feeding bread to ducks and geese because the birds can develop a condition called "angel wing," which leaves them unable to fly.

As many as a dozen birds are euthanized every year in Ottawa because of development problems with their wings that causes their flight feathers to grow twisted or upside down, said the city's Wild Bird Care Centre.

Angel wing is often the result of ducks or geese eating a high-carbohydrate diet, according to Patty McLaughlin from the rehabilitation centre that takes in approximately 3,400 birds each year.

The condition can leave birds unable to fly and can lead to "not a very nice death in the wild" because they either fall victim to predators or don't survive the tough Ottawa winters.

"It's a developmental thing. As they're developing their bone structures, their diet isn't right … It's people feeding them food that's not good for them. They love it. They love bread. We all love our carbs," said McLaughlin.

"People are feeding them junk food basically, so they fill up on bread, they don't know when to stop. They're not going to eat the good stuff that they need to develop their bones properly."

Birdseed or corn instead

McLaughlin said ducks and geese with angel wing are often found on golf courses and in drainage ponds in subdivisions.

The centre does not have the resources to go out and capture birds, so they rely on people bringing them in.

McLaughlin said they can sometimes help a duckling or gosling with the condition, but once a bird is fully grown there is no chance of reversing it.

"Being able to capture them and bring them to the centre, at least we can humanely euthanize them," said McLaughlin.

"They're fine out there to live through the summer if they have open water and stuff to feed, but come the winter time that's when things get quite harsh for their likelihood of survival."

The centre recommends feeding ducks or geese proper birdseed or frozen corn instead.