The Canada goose pictured above at a local park is afflicted by Angel Wing, which causes the ends of its wings to poke out at an odd (and useless for flying) angle. You may see birds like this in local parks where they're fed by us humans, and one theory is that the disease is caused by that artificial diet, that causes the wrist joints to develop poorly in the young birds. A competing theory is that it is a genetic disease, though in one Swedish experiment, putting an end to feeding resulted in no Angel wing in the next year's offspring which seems quite compelling. Wikipedia tells all, but either way now you know what you're looking at when you see them in the park.