I have an Aussie and she is a wonderful chicken herder! We go at it a little differently than folks who herd hoofstock, but it works for us and our situation. She moves chickens up and out of 'prohibited' areas as well as pushing them out of the woods when they get too far away and won't come when they're called. (This is not chasing, it is calculated behavior.) I can also tell her to 'take care of it' if there is a fight in the barn yard or a rooster is just getting a bit too obnoxious around the hens. The birds aren't afraid of her but they respect her and generally fall into line. She is never physically aggressive with them.
I love watching her work, especially when she drops her head and moves very purposefully. It's amazing how the prey drive can be shaped. She loves working the birds. Lately, her favorite thing is escorting the guineas off the porch!
Granted, Pheobe comes from working stock with a very high drive and it took a few years to get to this place where I trust her without reservation, but the work was worth it. (She never killed any birds, but as a puppy/young dog she had two speeds: wide open and stop, neither of which were predictable around stock.) She is four years old now. She does check back with me, but most of the time it's from a distance. They don't all feel the need to come back to you every time if you teach them early on to wait for direction on the out.
Aussies are like humans with fur, especially after they become mentally mature. You'll never find a more loyal or intelligent all-around dog in my opinion. They are both farm dogs and lap dogs. Ready to work or play anytime but they know when to turn it off and just chill.
The thing about training herding dogs is to not throw them into it before they can mentally handle it. Puppies only understand what herding is in relation to chasing. They know it's fun and their instinct tells them to go for it. Should something happen and they get corrected, perhaps many times or over zeallously by their human or the stock itself, a diminished desire to work could form. OR the opposite and they just become dangerous around stock. OR, they learn all kinds of bad habits that are hard to work out once the strategic training begins. Keep in mind, you are working on modifying the prey drive. That is what herding instinct is all about. Most working dogs aren't put into training until they are at least 2 years old. They may be introduced to stock, even had instinct testing done, but as far as allowing them to run with the animals or attempting to teach them herding as a whole- that's not a good idea. They just aren't mentally developed enough to handle it.