"in Eugene, Oregon, they are finding that the wings of waterfowl are becoming deformed from a steady diet of bread that is too high in carbohydrates. The deformity makes birds feathers grow faster than their wing bones.
Nearly a year ago in Spokane the Parks and Recreation Department launched an extensive educational campaign to let people know how feeding wild ducks and especially feeding them bread is one of the worst things you can do for the ducks.
At the time there was significant media coverage of the campaign. We also implemented an Adopt-a-Duck Plan and found new homes for 40 domestic ducks in the Manito pond that were unable to fly. Now we are finding other medical reasons why feeding waterfowl bread is one of the worst things you can do.
When a young bird eats calorie-dense, nutritionally poor foods like bread the growth of its feathers outpaces the development of its wing bones. Gravity pulls the heavy feathers down, and the growing bones twist outward, resulting in a syndrome known as Angel Wing. Bandages and physical therapy can correct the condition in young birds, but it is incurable in adults, and affected birds lose the ability to fly.
Parks and Recreation Horticulture Supervisor, Steve Nittolo, has spent several months working on ways to improve water quality in city park ponds. It all goes back to the public dumping bread into park ponds believing they are helping feed the wild ducks, when instead they are really harming them, Nittolo said.
In Eugene many people have noticed injured birds and reported them as having broken wings. But whats really happening is the angel wing, condition, marked by a deformed wing and spindly features that poke out at right angles.
Bread is bad, bad, bad, said Michele Goodman of the Webbed Foot Wildlife Rehabilitation Clinic in Connecticut. Bread is actually like junk food for waterfowl, Goodman added. Handouts such as whole slices of bread, pizza crusts and bagels can actually cause birds to choke to death. Feeding birds also can cause them to lose their natural fear of humans, and that can lead to aggression."
http://www.spokanecity.org/services/articles/?ArticleID=1850
The "too much protein" theory never made sense to me at all. Protein in most animals (including people) is rather self-limiting. While too much protein in human diets gets blamed for all kinds of illness, actual testing of that theory shows excess protein is only a problem when there is an absence of the necessary fats (essential fatty acids).
In many primates that were assumed to be vegetarian, it wasn't until animal protein was added to their diets that they successfully bred in captivity. Captive gorillas are having more and more issues with heart disease and obesity because their zoo diet is high in soy, wheat and corn...things they were not designed to eat.
I ended up studying animal nutrition as part of my studying human nutrition. If there are dietary causes for health issues, a LOT of them can be traced to sugars and starches. Soy, wheat, and corn are often the source.