[stonemetal]

I would hazard a guess that since teaching is a pink collar profession you would find more females in the Math Department since some of them plan on teaching it in high school. This doesn't happen for engineering since engineering isn't taught in high school. (Note: at least in the US to teach something at the high school level you typically major in it at the university level as well as taking teaching courses on the side.) The only female I know in graduate school math wants to teach college.