Last updated: 11 April 2022
Swans are beautiful and elegant birds found in many parts of the world. The sight of a swan family gliding gracefully along a river, with the male (or cob) and female (a pen) followed by their brood of fluffy cygnets, never fails to attract our admiration.
Swans are some of the largest flying birds, with wingspans up to 3m. They can easily weigh 15kg and need to eat up to 25% of their body weight every day. So what do they actually eat?
Swan are primarily vegetarians, so their nutrition comes mainly from plants that grow under the water, though they will eat insects occasionally. This typically happens when tiny fish, tadpoles, worms, molluscs, fish and frogs eggs become entangled in the weeds that the swan is eating.
The question is, should we humans be helping by feeding them? In this article, we go through the basics of swan nutrition and tell you everything you need to know about the dos and don’ts of feeding swans.
Swans mainly eat aquatic plants
Swans can survive quite happily without us feeding them. If you do want to feed them, stick to foods they’d naturally seek out, such as:
A group of swans eating corn
Feeding any processed human foods to swans can result in nutritional imbalances or lead to potentially dangerous digestive blockages, which can even be fatal.
Never feed any of the following to swans:
Also, only offer small amounts of permitted foods (in the section above), and stop feeding as soon as the swans lose interest.
A family of swans eating duckweed
After six weeks in an egg, baby swans, or cygnets, emerge into the world covered in fluffy down and with their eyes open. They are referred to as ‘precocial’ meaning that they are relatively mature from the moment they hatch. They’re ready for their first swim within a couple of days.
Before they hatch, they absorb the last of the egg yolk, so they can go without additional food for the first 7-10 days. The yolk is packed with nutrients and also has the advantage of being highly digestible before the cygnets are ready to deal with plants and insects.
But during this time they’ll start learning how to forage for insects and vegetation. By the time their food store is gone, they’re capable of feeding themselves properly, though perhaps still with help from their parents.
For the first seven days, they aren’t able to dip below the water (also known as ‘up-ending’), so any food they take will be on or just below the surface. Both parents may help by pulling up plants from the bottom, or by ‘food-trampling’. This involves paddling wildly for a few seconds, in shallow water, to stir up debris and food that may be lying below and make it easy to catch.
After around two weeks, the cygnets can dive below for longer periods, and pull up weeds for themselves.
Young swans watching their mother dive for weeds
Swans are primarily vegetarian. Although, on occasion, they may eat fish, frogs, insects, worms, and molluscs, this is usually by chance. The victims probably just happen to be in the vicinity of a tasty chunk of vegetation the swan had decided to grab and don’t move away fast enough.
Interestingly, cygnets are more likely to eat animal matter than adults. As they grow, the amount decreases, and by adulthood, their diet is almost entirely composed of vegetable matter.
For these reasons, feeding fish to swans isn’t necessary or desirable. Please don’t do it.
In freezing temperatures, the foods that swans typically forage may be in a shorter supply, so they'll seek alternatives such as berries and tubers. If you want to help them, go for leafy greens such as lettuce and spinach, and tear it into small pieces.
It's also possible to buy swan food pellets with grains, oils, and minerals, which float on water.
Swans foraging underwater
Swans don’t have teeth. To grind their food to a mush, they use a structure called a gizzard, which aids digestion by increasing the surface area of whatever food they swallow.
But even after this, the swan can only extract small amounts of the nutrients it needs. That’s why swans need to eat around 25% of their body weight in food daily. A 15kg swan needs to find 3-4kgs of vegetation every single day.
Many of us have fond memories of feeding bread to the swans in our local parks and rivers. However, opinion is severely divided as to whether it is harmful or not.
One statement, endorsed by Professor Christopher Perrins of the Edward Grey Institute of Field Ornithology at Oxford University, explains that swans have been eating bread for hundreds of years, and there is no evidence that it harms them in any way– providing it isn't mouldy. It may also be an essential supplement in winter when vegetation is scarce.
The other side of the argument is that bread doesn't provide much nutritional value to swans, and if they fill up on bread, it can mean they aren't getting the required nutrients they require to survive and thrive.
Our general advice is not to feed swans bread, and instead feed them other things like corn, grains and lettuce. These types of food provide swans with much more nutritional benefits.
So if you decide that you want to share some fresh bread with swans, give small quantities and stop throwing as soon as they lose interest (or keep throwing and let the ducks take over!).
Mute Swan diving for food
In winter, when their typical food sources may be in short supply, greens such as lettuce, spinach, shredded carrots, celery, and other vegetables make a helpful supplement. Remember to cut up the veg into small chunks because swans can't tear or chew their food.
Fruit isn't a natural food for them, and the skin of apples may be toxic for swans – so stick to the veg!
Nuts don’t form part of a swan’s natural diet, so don’t offer them. As an alternative, try throwing some green peas or corn onto the ground rather than into the water.
There have been reports of swans attacking mallards and ducklings, but this is likely due to fights over territory rather than an attempt to get a meal.
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