GENERATIONS of families have strolled to beauty spots armed with bread to feed one of the country's most popular birds.
But wildlife experts in Scotland have urged the public to help save swans by feeding them brown loaves instead of white.
A lack of nutrients in white bread is leaving the birds crippled with a condition similar to rickets in humans. Their limbs become so weak that the birds are unable to dive for food.
Leftover bread in the water can lead to poisonous blooms of blue-green-algae, posing another danger to the birds.
The problem is particularly acute at the mouth of the River Ugie near Peterhead in Aberdeenshire, where scores of mute swans have been taking advantage of free food from the public. But officers of the Scottish Society for the Prevention of Cruelty to Animals have found that white bread has made them ill. Scott Elphinstone, an inspector based in Buchan, said: "The birds have become reliant on white bread because that's what the public feed them.
"But they are becoming crippled due to a vitamin deficiency – white loaf is just not good for them. We would advise anyone who wishes to take down food to take along brown bread instead. Potatoes, bird seed and carrots are also a much better choice."
A spokesman for the RSPB said: "We would agree that white bread isn't ideal for the diet of any bird. It is much better to give them brown or wholemeal bread which contains seeds as white bread doesn't have as much nutritional value."
But Carina Norris, a nutritionist and keen birdwatcher, said the difference between white and brown was not so clear-cut. "White bread is fortified with two vitamins, calcium and iron, so it is not devoid of goodness. The reason brown bread is better for you is that it provides more fibre and the nutrients are more easily absorbed by the body."
The mute swan has become one of the most common features of rivers and parks across Britain. It is thought that wild swan populations have increased over the years due to increased protection. Their main threats come from river pollution, fishing tackle, vandalism and overhead power lines.
The waterbird survives on aquatic vegetation, such as molluscs, small fish, frogs and worms, which they dig up from under the water with their long necks.
However, bird experts fear an increase in poisonous algae will kill off their natural food resources, putting them at risk.
As well as being poisonous, it reduces the oxygen level in the water so there's not enough to support large numbers of fish.
Mr Elphinstone concluded: "While we do not want to discourage people from visiting the birds and feeding them, we would hope they would feed them with more appropriate foods."
NUTRIENT RICH DIET
SWANS feed almost entirely on underwater vegetation or grass.
Their diet includes pondweed, stonewort and wigeon grass, as well as tadpoles and insects such as milfoil. Those living on salt water will often eat molluscs.
As well as avoiding white slices, it is best to avoid giving swans stale bread, as mould is poisonous to them.
Food should also be thrown into the water so that they can swallow water with the food – feeding them on land is environmentally unsound and encourages the swans to leave the water, which can cause them harm and put children in danger.
Swans will not over-eat, but they can become dependent on a few repeat sources of the same food. Carina Norris, a nutritionist, said: "It seems swans have a diet high in vitamins from tadpoles and insects and these same vitamins won't be present in white bread in the same quantity.
"Anything with seeds in, such as wholemeal bread, would be better."