Ever since 8th/9th February, when Zoe cleaned out the Augean stables that Box3 had become, Harry has continued to roost overnight, leaving more poo as he does so. Each morning, Zoe has come to clean it up again.
Now that there is only one night's mess to clear up, the task is quite trivial. Here comes Zoe on her first visit of the morning. You can see 4 droppings on the floor of the box and I think there are a few more that we can't see on the shelf where Harry actually roosts.
Zoe goes to the first one ...
... and picks it up.
She immediately turns to the exit hole ...
... and takes it out.
These are very quick visits of Zoe's - she doesn't hesitate at the entrance hole when going in, nor does she waste any time when inside or leaving the box.
I suppose she will continue to do this until she starts building the nest. Then she will probably want to roost in the box herself so it will be interesting to see what happens then - another fight perhaps?