Also, keep in mind that collies are herding dogs, so it is likely he/she will try to herd your ducks. Another thing, did you ask your mom the reason she doesn't want ducks? If you know why, then maybe you can find a way to fix the problem. I did this a lot when asking to get my Yorkie. I would do research, ask my parents why not to get one, then give them an answer based off the information I already know. If I didn't know, i would research some more, then find a solution to the problem. It worked! Rosie is almost a year old now.
