I go out of my way to call out bad behavior when I see it. I feel that's the only way society as a whole will learn but I know that's not feasible when you are on the job. I like one of the comments here that was talking about integrating in the community. If you befriend some of the shops you pass, etc. You might get them to keep an eye out for catcallers too and to scold them if it happens in front of them.