4 Ugly Ducklings

I think NOT, they're little beauty's all fluffy in grey/brown, along with their parent by their side.
One egg still on the nest that hasn't hatched & I wonder where is the other parent?
When we first visited the Swan's there were 2 parents & now only one.
I popped by around a week ago & there was only one adult then; I hope the missing one is safe.