Swans consist of 6 (possibly 7) species that are distributed throughout the world either naturally are by introductions. In Britain swans are protected under the Wildlife and Countryside Act 1981 making it an offence to injure, take or kill a wild swan. Up until 1998 killing or injuring a swan was classed as treason, now The Crown retains the right to ownership of all unmarked mute swans in certain stretches of the River Thames and each year the Royal Swan Upping is held to count and inspect the swans on these areas of the river.
There are 6, possibly 7 species, of swan - The Mute Swan, The Black Swan, The Black-Necked Swan, The Whooper Swan, The Trumpeter Swan, The Tundra Swan (Bewick's are considered a sub-species). Three of these swans can be found naturally in the UK - The Mute Swan (all year round) while the Bewick and Whooper swans are migratory and found in winter months.
Black swans are not native to the UK as they are from Australia and New Zealand and the ones seen in Britain have been brought in for breeding and sold to private owners. Some have escaped into the wild and may be seen occasionally with Mute swans. (ref: http://www.theswansanctuary.org.uk/general-information/ ).
According to the RSPB there is 6,400 pairs of breeding swans in Britain while the number increase to 74,000 birds that overwinter throughout the UK, coming from Europe and Russia. The most common swan is the Mute Swan and can be seen in many areas of open water and on rivers.
The number of breeding swans appears to be increasing, and this may be partly due to increased awareness by anglers not to use lead weights when fishing in areas that also have swans, as swans often accidently swallow lost lead weights leading to led poisoning. Another hazard is lost fishing lines and hooks that can get tangled or caught on swans, causing injury or death.
In other countries Mute swans have been introduced and bred rapidly leading to a challenging situation where environmentalist have called for the swans to be removed from lakes and waterways as they compete and harm native bird species in these areas. This has caused widespread condemnation of proposed culls in areas of the United States as swans are loved and admired by many people. It is a delicate situation as native bird species and environments need to be protected, ideally it can be achieved long term by using non-lethal methods of reducing bird breeding to keep the numbers of swans down so they do not cause problems for other native north American bird species.
Swans usually have one mate and this is believed to increase the chance of successful breeding. While swans mate for life they will and can get another partner on the death of a mate, or in other circumstances.
I still remember the campaigns regarding not feeding swans, and it is still ingrained in my memory. So can you feed swans, and specifically can you feed swans bread? The answer is yes as long as the bread is fresh and has no mould on it (bread if left for too long will have fungal growth which is unhealthy for swans or other birds).
You can feed swans other food including grains, wheat, lettuce and potatoes. If swans are already on water do not encourage them to come out to feed, throw the food into the water for them.
When swan / ducks stop feeding eagerly, then stop feeding the birds as you will only add to organic material in the water that sinks and rots. Keep it fresh and vary what you feed the birds. Ideally feeding in colder weather is best when food is scarce and allow the birds to feed naturally in late spring through to autumn.
Migratory swans - Bewick's and whooper swans, can often be seen on farm fields where they will feed during winter months.
Mute swans while often found on fresh water can also be found on coastal estuaries feeding at low tide. These swans will a range of plants and algae, along with small insects and some shellfish.
Along with the Crown there are three organisations that have retained their right of ownership of mute swans and maintained their unique swan marks. Current day ownership marks are made by way of a small numbered leg ring but all Crown birds are left unmarked. Abbotsbury Swannery was granted the right of ownership in the fourteenth century and two London livery companies, the Vintners and the Dyers, have held similar rights since the fifteenth century.
Many swans in the UK have been ringed for identification and scientific purposes.
Useful links: Vinters Hall on the Swan Upping and also a pdf document full of information on this event.
The Swan Sanctuary - about swans and the visitor attraction.
The Royal website has information on swans and the Swan Upping as well as the history of swans in Britain.
The RSPB has a useful guide to identifying the different swans in Britain. The information pages are for the Bewick's Swan that make the journey from Siberia, Whooper Swans that come from Iceland to overwinter, and Mute Swans that are found throughout the UK and breed, many of the birds being permanently resident.
The Flight of the Swans website has information on the Bewick's swans and conservation efforts regarding this swan.