How do I move 4-wk feral kittens out of my barn?

Lizzie, Is right. You can put the kittens in a pet taxi and leave them nearby but out of the way. The Mom will hover nearby. When the hay is loaded and not before open the taxi and let her handle the moving project. It will probably be a good idea to feed her near there.

There are a lot of pet organizations (SNAP, CAP, HSUS) that have Trap Neuter Release programs at low or no cost. They often loan traps. We has a LOT of feral cats move in and it was flat out of hand. This got us out of a bind. Now our population is stable at about 20. My cost was just my time and gasoline to transport. I donate to the program every now and then as they really helped us a LOT.

Oh, and yes a spayed female will still hunt, what the heck, she has nothing better to do????

At 4 weeks the mom is weaning they off of her milk so it is important that you do not interfere with that process to much. Is there another place in the barn you can put them till they are older? I would guess that if you bother the kittens enough the mom will move them herself. Please keep in mind the mom will just keep having kittens until she gets fixed. The BEST thing to do would be to get a humane cat trap and the bring her and the kittens to a no kill shelter. You should try to get them homes. If you let them all be wild this will likely happen again.

If the mother runs off, then get the kittens and if possible put them in a crate or something they can't escape from while the hay delivery is being delivered, then let them back out. Mama cat will come looking for them.