I've noticed a trend.
In a Bikram yoga class, there are either enough men for someone to remark, "Wow, a lot of men practice here!" or one token man (often me) standing among the scantily clad females. We've all heard that yoga attracts more females and all that, so that's no surprise. I think I find it more surprising that when men show up, they seem to naturally show up together. If I were an anthropologist, I would actually research this.
Oh one other thing, they seem to show up for certain teacher's classes too. At both studios I know fairly well, if there's going to be a lot of men, they're probably showing up to this teacher's class. I just don't get why. Maybe it's all happy coincidence-I just enjoy seeing it.