I have a wired fence... but most predators clear it easily. I mean electrified.... Well placed, it's very effective.
Adding your general location to your profile might help other make the most relevant suggestion possible at a glance.
I wouldn't clear ALL the bushes... as they are great cover and where my birds hang out most the time. Low cover is especially key to preventing aerial attacks.
All holes covered in 1/2 inch hardware cloth and locking up every night... so the predators who do visit know there isn't an open buffet. If they get used to getting nothing every time they come they won't be enticed to keep coming ans then the ONE time you forget to lock up you might get lucky and be safe. My neighbor who didn't lock up no longer has a flock. In 10 years I haven't lost any to night time predators.. yet. I did have one duck scalped by a coon when they were in a makeshift grow out coop. That duck survived and so did the coon.. as I bought a trap... but beefed security instead.
I lost my first chicks to hawks last year. 2 or 3 stolen from a broody Silkie. I put the chicks on lock down, the hawk stalked for several more days. I added fishing line above that Silkie pasture (mine were ALWAYS free range regardless of peeps who swear Silkies can't) and haven't lost another chick since then. Predator load varies by season for me. Having my own dog
s patrol is definitely a measure that cannot be discounted. More than one.
My predator load is heavy here and never ending... a rooster is no match. But I LOVE living among the animals and trees.
Guess I will always try to get people to live in peace. It's hard to forget all the ranchers and such hunting the wolf to extinction here in California or places like Yellowstone where the gross imbalance has left the land hurting to the point they are reintroducing them.
I totally get the need to protect what is ours!!! But we CAN do it with a kill them all mentality.
That isn't to say I'm against trapping and dispatching... we all need to do what we need to. I just mean if there IS an alternative.
How many ducks ya got? Have you actually seen activity at dens?