The trouble with 301 redirects and backlinks
On the SERoundtable the question is raised whether you can check if a site 301 redirects to your website, referring to a thread on the SEW forums and an article by Aaron Wall. That seems quite simple to me, as most of the times you’ll see clicks coming in from sites on which your own site doesn’t have a link, and you can just test which one goes to your domain.
It’s way more difficult to check for sites for which you can’t look into the logs though…. 301 redirects can be picked up (and thus affect the ranking) within a matter of days, whereas the backlinks to that 301’d page or domain might take months or even up to a year to show up in your backlink checks, if they ever do that all. (Think about it, 301 splitting still works…)
This is one of the reasons why you shouldn’t be checking just your own rankings, but entire top 100’s for your keywords. If one site goes up incredibly, and another one is suddenly gone, it might well be that the one was 301 redirected to the other… I’ve seen up to 4 sites disappear at once, with their complete juice being redirected to 1 other site, which was skyrocketed into the top 3 on a competitive keyword, from being down in the top 20…