You can use bigger holes. I used 1" chicken wire with snow fence over it. I build the runs as big as I have space for. The run for my Muscovies is about 12 by 12 feet and the Pekin one is bigger yet. I have five acres, though, so I have plenty of space. When I was young, we put 2 mallards and 1 muscovy into a 6 by 12 pen and they did fine.
Sorry--I forget that unless you live in a snowy area, that doesn't make sense. My apologies. The orange plastic fence in the photo is
snow fence. It's very strong and has 1" open squares. I used it to cover the pen because it's lightweight. It's used as a "stop" for snow--it slows blowing snow down and makes it drift were you want it to instead of where nature puts it. It's great for blocking wind, too.