What gender and age groups typically respond to a mail survey?

I am writing up survey results for a community survey done by a park and recreation agency. A couple of the Board members may say that the results are not representative of the population because the ages and gender of the respondents don't match community demographics (e.g. 48% of the population is female, but females comprise 65% of those who answered the survey). Age brackets of respondents also do not match known local demographics. I believe that certain demographic groups are more likely to respond to a survey than others. But I could be accused of stereotyping if I said in public that retired people with time on their hands might be more likely to respond. Is there any known research that confirms survey respondent profiles? Thank you!

What gender and age groups typically respond to a mail survey?
Females b/c i'm a guy and i hate mail surveys. but my female friends always send them to me and say they filled it out so i need to, but i never do.
Reply:w/f senior citizen...