I have a border collie cross, she was a city dog for her first 5 yrs. I introduced her to the geese that are at the farm, she did try to nip at them, but when they turned the tables, she quickly backed off.
I let her see the chickens, with her outside the pen. She did want to herd them.
I worked with her on commands, such as "OUT", down, heel, and the sit/stay. When I got her understanding and doing those commands, I had her ON leash with me in the pen.
The "Out" command is for her to get away OR out of the area. I use it with horses and the chickens.
IF you have a large yard and can let out a few chickens, keeping her ON a leash or long rope, slowly introduce her to them. Using commands with the NO! and "Get of it!" (an australian term- I think).
Keeping the dog next to you, so she learns she can be around these animals but is not allowed to do anything TO them.
My BC cross will whine and pace outside their pens, they are in stalls for the winter with plastic up so she can't see them. BUT I allow her in, and she is right by my side, watching them, NEVER hurting or herding them.
She is 9 now so it wasn't easy but I ride with her when I am on my horse, they help me keep the goats and horses at bay when I have to go into a pen OR open up a gate.
Training, praise, and consistency are the keys.
Hope this helps
Carol