Takes knowledge, too!
Well, yes, knowledge of how to achieve the foundational obedience in the first place,...or we dog trainers would be out of work!

But introduce your already-obedient dog over several weeks to the chicks in a controlled setting where he can't hurt them, gradually moving up to letting him sniff while they are in your protective hand. He should be calm, not excited (yum, prey dinner!) or staring fixedly at them (intent to attack). And true again, a professional would be able to teach you what his reaction to them is saying. You should already have a "leave it!" command already established (why my dog only barks at rattlesnakes, not engages). Use your leave it! command repeatedly and praise him for being settled and calm. The most crucial part is when you allow them to walk around in front of your dog. Use e
xtreme caution! Have him tied or have someone else firmly holding his leash, use your body or a low barrier to block any rush. Allow the dog to see the chicks loose, but at a distance so he can't lunge. Train him again to "leave it!"
Before I was a dog trainer, I properly taught my dog to leave the chicks alone in their box with a screen lying on top. He could easily have moved the screen, but he didn't. But not knowing better, when they were big enough I let them out in front of him on the grass and went inside. Yup, he ate every one! Chicks running free are not chicks in the box! That's why your housebroken dog may piddle in someone else's house. We think we've trained them not to piddle under a roof. What they really understand is not to piddle under
their roof! Likewise with the difference of chicks in confinement and chicks running free. So this part is almost like training all over...It takes a lot of time and patience in a controlled setting with very, very gradual steps....