Will poultry predators pass through a barn?

I need to add some fence to enclose some pasture that I am using for a poultry yard. I currently keep a few ducks in this space, but I anticipate using it for chickens, ducks, or geese at various times. Maybe sheep or goats some day. The pasture is already enclosed on three sides with woven wire. I plan to add a couple strands of electric wire. The simplest way to seal off the area is to run a fence on the 4th side, up to the side of the barn. This would leave easy passage through the barn for me, but also for potential predators. The main concerns here are foxes, coyotes, raccoons, and bobcats. The barn is on a cement pad and I am in it almost every day, so it should have a strong human scent. I suspect foxes, coyotes, and bobcats would be unlikely to pass through this space to reach the pasture, but raccoons seem bolder.

Right now, the ducks are locked up safely at night, but it would be a big convenience if I could just train them to enter an open shelter that would protect them from owls at night. But if I do this and a raccoon comes through the barn, they'd be sitting ducks.

Does anyone have experience with a similar situation? I'm sure the answer to how risky this is, is 'it depends'. I guess it will depend on how habituated the predators are. I don't yet have a good sense of this as we just moved here. What other factors might matter?

My experience has been that predators will enter / pass through a barn.  

John is right. Common chicken predators will not be phased.  I have had a coyote walk down a city a city side walk through a group of 3 adults in broad daylight without skipping a beat.

When they are on the prowl they are not put off by much and can be quite innovative.

Bigger animals would be more alright (although you may want to look into electric netting or guardian dogs), but always lock up the poultry. A determined predator would do almost anything, regardless of the human smell, to get food. I had a couple of my chickens I kept in an open space in the back of the barn for a while and learned the hard way. They were in a narrow hallway between the hay and the grain bins, and definitely not easy to see from a predators outside view. I managed to get out there soon enough after the first owl attack, and put up paneling around it that was pretty secure (no huge gaps, and definitely not something an owl could fly into). Thinking it was fine, I went back inside and went to bed. It wasn't, and I ended up losing one of my best layers, and having to do heavy stitching on another hen. Owls are incredibly smart, and when they spot an opportunity, even one that involves crawling through a tiny gap, they will take it. Geese would be another safety option, but they are still tasty to a predator. The nice thing is that it isn't as hard as you might think to build a safe coop, especially if you're starting from a barn that already has secure outer walls. Good luck!