River Thames to the strong current of the river, but also other river users. Organised swimming events take place at various points generally upstream of Hampton Court, including Windsor, Marlow and Henley. In 2011 comedian David Walliams swam the from Lechlade to Westminster Bridge and raised over £1 million for charity. In non-tidal stretches swimming was, and still is, a leisure and fitness activity among experienced swimmers where safe, deeper outer channels are used in times of low stream. A Thames meander is a long-distance journey over all or part of the Thames by running, swimming or using any of the above
River Thames inland. These include cormorant, black-headed gull and herring gull. The mute swan is a familiar sight on the river but the escaped black swan is more rare. The annual ceremony of Swan Upping is an old tradition of counting stocks. Non-native geese that can be seen include Canada geese, Egyptian geese and bar-headed geese, and ducks include the familiar native mallard, plus introduced Mandarin duck and wood duck. Other water birds to be found on the Thames include the great crested grebe, coot, moorhen, heron and kingfisher. Many types of British birds also live alongside the river, although they are