Recently many of my niche sites are dropping in the SERPs (from mosty being on the top of page 1) to the top and middle of page 2 for their main keyword (same kw as domain name). Some of these had been sitting at the #1 spot for quite some time and all these sites are about 3 years old. It just seems every week now since late April/early May they dropping a few spots every week until they move to the second page. It is like a gradual drop over a period of some time. For some of these sites I started doing link building campaign again when I noticed this happenning, but still no help with the slide. I can't pinpoint what could be causing this across so many of my sites since some of these sites got new content a few months back while others have not been updated for like a year. I don't it is the competition getting more backlinks since most are internal pages of retail merchants not focusing on the term. Could it be the static content on the homepage and I should try to add fresh content on the homepage and also get some high PR backlinks? By the way these sites are monetized by Adsense and I do not interlink between them. So anyone else seeing similar drop to their sites and have any feedback?