Overpopulation and underpopulation and the problems they present are the topics of this category.
Regular Blogs
Discusses all manner of topics about the environment, ecology, and geology and spends quite a bit of time and effort to document and explore the subject of overpopulation.
http://geogy.net/
The Environment blog at the New York Times offers numerous posts about the connection between overpopulation and environmental degradation, literacy, hunger, and drought.
http://green.blogs.nytimes.com/
Does what it calls fact-checking about the concepts of overpopulation, climate change, poverty, and abortion and includes inters about the demographic collapse, China and its one-child policy, and how to feed more than seven billion people.
http://www.ruthblog.org/
The focus of this blog is the overpopulation of humans on the earth and the problems which are attendant with that phenomena.
http://thisshrinkingplanet.blogspot.com/