Study the backlinks to a few related sites, such as BasciallyBats.org, Batcon.org, BatResearchNews, and North American Symposium on Bat Research (NASBR), and you see that each of these sites tends to link to the other, and vice versa. The reciprocal linking percentage across the top five sites is over 80%, and for the top three, it's 100%. And this reciprocity percentage is perfectly natural, believable, and in no way an attempt to fool any algorithm or improve rank. These sites link to each other because they share the same passion for a very specific topic and want to make sure those people visiting and reading their content find the other sites about the same topic.
