This swan was swimming in a lake in Germany and had gotten used to eating food thrown to it by passersby, much as our mallards have here. I had never been that close to a wild swan and it was impressive, especially if you are used to the ducks around here.
Mute Swans were introduced to North America from Europe. They are considered invasive in the United States because they were brought over to look nice on ponds and lakes. Swans readily adapted to our climate and, as with most introduced species, became a pest. It does not help that swans are aggressive, much like geese, and territorial. Image being attacked by a bird that weighs in at 25 pounds and has a wingspan of 7 or 8 feet!
In addition to the aggression problem, swans eat up to 20 pounds of aquatic vegetation. This deprives other birds and fish of the food and removes vegetation many species of fish and small invertebrates use as nursery sites for their young. Even though the swan is not directly feeding on these creatures, there is a major impact on their numbers as collateral damage.
Swans mate at about age three and stay with the same mate all their lives. In February, courtship begins and nest building is undertaken in March or April. Four to six eggs are laid and take just over a month to hatch. They swim almost immediately after the parent and remain there until the fall. Swans can live 20-30 years.