My chapter had a local mascot of the bumble bee because a bumble bee is black and gold, but there is no meaning or anything with it other than why we picked it. I have seen other chapters used cats as well.
I have mixed feelings about having an animal mascot. On one hand it would be nice with decorating/collecting purposes, as long as a meaning was put behind it rather than having one just to have one. On the other hand, I like that we dont have one because it is yet something else that makes us unique!
I believe a similar discussion happened a few years back regarding the establishment of a fraternity jewel.