That's why I only let the ducks in the garden AFTER I have harvested everything I want out of it
The hunt down the slugs and dig up the eggs too so it does help with the slugs even if they aren't in an area full time.
The main reason I started looking in to owning ducks was because my yard is infested with slugs. Having ducks has greatly reduced the population. The funny thing is I am in Colorado...semi arid. How I ended up being infested with slugs is beyond me