Why bread in particular is bad for ducks
Not only can bread be fattening for ducks and make it harder for them to fly and otherwise evade predators, feeding ducks bread can also lead to other problems.
Duckling malnutrition: In an area where ducks are regularly fed bread, ducklings will not receive adequate nutrition for proper growth and development. Furthermore, because ducks will naturally seek out an easy food source such as human handouts, ducklings will not learn to forage for natural foods as easily.
Overcrowding: Where an easy food source is abundant, ducks and other waterfowl will lay more eggs and the pond or lake will become overcrowded. This makes it more difficult for the birds to seek out healthier food sources and increases the likelihood of territorial aggression.
Pollution: When too much bread is offered to duck, not all of it will be eaten. The soggy, uneaten bread is unsightly and rotting bread can create noxious odours as well as lead to greater algae growth that can clog natural waterways. This concentrates the pollution and can eventually eradicate fish and other life in the vicinity.
Diseases: Feeding ducks bread can increase the spread of diseases in two ways. First, a carbohydrate-rich diet leads to greater defecation. and bird faeces easily harbour bacteria responsible for numerous diseases, including avian botulism. Second, mouldy bread can cause a fatal lung infection that can decimate entire duck and waterfowl flocks.
Pest Attraction: Rotting supplies of food leftover from sated ducks will attract other unwelcome pests such as rats. mice and insects. These pests can also harbour additional diseases that can be dangerous to humans.
Courtesy: Richard Harris MSc, BSc
Nature Conservation Manager, London Borough of Camden