Think about this: There are worm eggs deposited onto and into the soil by infected birds. The eggs are picked up and swallowed by birds, starting the worms lifecycle all over again. How do you break the lifecycle? Worm monthly. There will eventually be no eggs for birds to pick up because there wont be worms to lay eggs. My birds are penned and kept on the same soil, actually I use sand in my pens to deter parasites. Sand helps keep everything dry and I scoop poop several times a day as well. All of this helps deter worms. I use sand inside the coop(s) as well.
If your birds free range, there's less chance of birds getting constantly infected, depending on soil conditions and rotating areas where they forage. Keeping grass cut short helps as well as keeping everything as dry as possible.
If your birds free range, there's less chance of birds getting constantly infected, depending on soil conditions and rotating areas where they forage. Keeping grass cut short helps as well as keeping everything as dry as possible.