How big of a pen are you talking about.They are much better off on the ground,but if you have a huge pen with a wire bottom,say 10x10 they should do fine.Now you say you borrowed a pen,something doesn't sound right.Are these ringnecks you are talking about?
In N.H.,Tony.
You will need to provide her with a nesting box,she will not sit on egg on top of wire.She needs to be comfortable with her surroundings to set.Plus she needs to be with a male for fertilization.
In N.H.,Tony.