Not sure if your still looking or trying to figure something out but depending on the size of your chickens can help make your decision, I have a silkie and we have her in a figure 8 cat harness, as for why you would need a harness, I harness trained to be able to take her out so she can explore the neighborhood and the neighbors lawns. I began by getting her use to being held alot, then when she would walk right up to be picked up i started walking around the yard having her follow me, once she had mastered that I picked her up and slipped the front loop around her neck and adjusted it to fit snug enough that she wouldn't slip out but not tight, then i brought the back around and clipped it behind the wings so she still had full wing range, after she got use to having the harness on. i put the leash on and just let her walk around with it dragging, be sure not to let it get snagged. then after a while I picked up the leash and walked her around.