The empty swan's nest

A couple of weeks ago this was the scene on an island of the Wandle River: a swan guarding her nest, her mate swimming nearby.

Recently I was passing and the picture was rather different:

There were two swans swimming nearby, but no signets and the nest was empty.

So what happened? Was it foxes? for there are many that roam the streets of London and the island was easily accessible.

Or was it the ultimate predator, humans?