For very many years a pair of Mute Swans [Cygnus olor] have taken Urswick Tarn as their home and reared their young there.  Fiercely territorial, the cobs are intolerant to the presence of other male swans that may come to the tarn and also to geese which are persistently hassled on occasions when a flock of Greylag [Anser anser] and/or Canada geese [Branta canadensis] take up residence for a while in the meadows surrounding the southern end of the tarn.  The number of cygnets successfully reared varies from year to year but invariably the adults are good parents until the cygnets are sufficiently mature for self-care when they are encouraged with ever increasing vigour to find a place of their own and make way for the next cycle of breeding.  The maturing process includes the important capability of being able to lift their heavy bodies into flight and this requires long periods spent strengthening flight muscles and many attempted but failed take-offs from the water.  Eventually liberation to the air is achieved but exclusion from their birth home will shortly follow.