Having had my sailboat on a mooring for many years, and also on a dock for 4 years, I have noticed that bird issues on a mooring are very much worse on a mooring.
My theory is that birds fish in a harbor and then go to the nearest spot to eat and eliminate. That would be on a moored boat.
Boats on a dock cover most of the water so the birds don't swoop for their lunch near docks. And if the dock area isn't close to their fishing water, they don't eat and mess on docked boats as much as on moored boats.
YMMV.
My theory is that birds fish in a harbor and then go to the nearest spot to eat and eliminate. That would be on a moored boat.
Boats on a dock cover most of the water so the birds don't swoop for their lunch near docks. And if the dock area isn't close to their fishing water, they don't eat and mess on docked boats as much as on moored boats.
YMMV.