If you care about waterbirds please do not feed them. It is highly detrimental to their health because eating human food like bread instead of natural food sources like insects, snails and worms can cause malnutrition and sickness.
Grabbing a bag of bread crusts and heading to the nearest pond to feed the ducks and swans used to be a childhood institution. Some people might have fond memories of throwing chunks of bread to an appreciative gaggle of waterbirds and they may want to share the experience with their own children or grandchildren. However, it's important to remember that this nostalgic trip down memory lane can cause some serious problems for our feathered friends.
Bread makes waterbirds sick. They become reliant on it and stop eating their natural food. This results in malnutrition and disease because bread does not contain the nutrients required for birds to maintain good health. Dumping bread and vegetable waste into water bodies and waterways contributes nutrients to the system which cause algal blooms, oxygen depletion, reduces plant and animal diversity, and upsets the ecosystem. This can be lethal for aquatic life.
Feeding water birds can also make them less wary of people which increases their risk of being harmed and can contribute to aggressive behaviour, overpopulation and can even delay migration patterns. Young birds can die because they lack the skills to forage for food.
This doesn't mean you can't pack a picnic and go and say hello to the waterbirds. Ducks love to snack on snails and worms which are great for their health, so leave the bread at home and clear out your garden instead.