I do not know if the swan is "belongs" to the site,but I watched as the swan went to one place on the front wall,and called for attention/food.It's actions reminded me of an old story of swans in a priory moat,being fed by monks,when they "called" by pulling a rope with a bell,on the priory walls.
see http://www.britishlistedbuildings.co.uk/en-295292-horselunges-manor-hellingly-east-sussex