Sometimes that all-you-can-eat buffet does more harm than good. Many scavenger birds, like vultures and storks, supplement their diets by stopping off at large landfill sites and rubbish dumps.

In the past, some research has suggested that such sites are actually helping protect some species from starvation . But a new study looking at the health of these birds suggests that they may be paying heavy price for those easy calories.

Scientists Pablo Ignacio Plaza at the National University of Comahue and colleagues studied the effects of …