Wild goose chase?

The picture is very poor as on my phone and some distance, but it shows a swan and a canada goose.

It was taken today and Black Park County Park, Bucks.  I walk here most weekends with my dog.  I was there yesterday and this SWan was chasing the goose all around the lake and round and round this and another island.  The Swan has a mate, but the goose does not appear to.  A lady told me that yesterday the chase had been going on for about twnety mimutes and this morning it was still happening.

The swan would swim after the goose and then putting his neck flat on the water would try to peck at the goose. However when he eased off, the goose did not leave but stayed nearby and so it carried on.

Any ideas as the what is going on?

Sarah

I've learned that I still have a lot to learn...

http://www.flickr.com/photos/bramble67/