but I am still wondering..how you gonna benefit your blog ranking from posting someone else digg articles on your site?..just to get more information on you site?..but all digg links still go to digg..not to you..you better create more articles by your own...promote your content, not others..you want your site ranking not digg...from my opinion..all those diggs,reddit and other networks..they are good to be as news...they do not help
you at all..they are just doubling content in geometrical progression in the Internet(on site like yours)...making google do not give you ranking because it is not unique content..Google likes unique content that you write, not reposting info from diggs and others...more you write, more ranking you get..
For example, my husband is technical writer..he has many sites, that RANKING, he never had any diggs ...but he is number one in his area(topics)...
about your "own" posts:
that post starting with words "A seagull in Scotland has developed the habit of stealing chips from a neighborhood shop."
I searched google for existance of this phrase on the Internet..
Google gave me this:
About 942 results for "A seagull in Scotland has developed the habit of stealing chips from a neighborhood shop". (0.44 seconds)
942 results sounds ridiculous..there is nothing for you to write about on your own? Do you think google will like you after reposting it 942nd time?

If you really like that article about seagull, you could rewrite it in your own words..not just copy it..this way it would be unique content that google would appreciate..
We have so many garbage-copy-paste-steal blogs on the Internet...