Put up a sign that says “WARNING: rabid ducks, enter property at own risk”

Build a moat. It would certainly keep me out.

Build an exact replica of that area right next to the original. They’ll be confused, are they visiting the real ducks or a simulacrum of the ducks?

Give the ducks a nice shower/sprinkler set up that’s both timer and manually controlled.

train the ducks to chase after the enemies. Lol

I would have to go with landmines. If that isn’t enough of a deterrent, and claymores or even some bouncing betties.

"Entry Fee (min one):

• Carrot
• Apple
• …"

That way you get duck (or human) food for free.

You’re looking at this wrong way.
Buy a gumball machine. Put on fence. Fill machine with enough feed for the day. Charge other people to feed your ducks

Obvious answer is to give the kids ducklings for every visit. Pressuring kids parents to stop their kids coming over without permission. Unless they want to own duck pets.

depending on where you’re from you can hang up a sign saying “trespassing Children will be converted to Islam”

Had a friend with problem neighbors kids cutting through his yard to get to the store. He was friendly with the parents and didn’t want to stir shit. The neighbors were super all-natural, hippie, no chemical types, so he told them he switched to a new fertilizer packed with micro-plastics and forever chemicals made by Monsanto that he had to sneak in from Mexico because it wasn’t allowed in the US. That fertilizer sure worked because the trail the kids were carving filled right in that summer.

Get you some geese

Pro tip - feed them a handful of dandelion leaves twice a day, they’ll be your best friends

Trespassers will be trebucheted.

“There is at least one more bear trap on my grounds than you can spot.”