Swans and a Goose........

Not sure why this has happened but last summer on the Embankment at Wellingborough there was a Goose spending time with all the Swans, now this year there are three of them....Not sure why the Goose is there or how come it spends time with the Swans........they seem to get on and neither is bothered by the other......I guess the swans are young as they still have marking of cygnets......But today the swan had upset the Goose and when i got there the Goose was giving the Swan a big ticking off.....I have no idea why......