Well, you can navigate to the ScienceBlogs home page, and search there,
or go to any of the blogs and use the search boxes there.  Or,
to simplify things a bit, use can use a Firefox extension.

First, you have to get
Firefox, if you don’t have it already.  The install
the “Add to Search Bar” extension ( href="https://addons.mozilla.org/en-US/firefox/addon/3682">install
here).  Once it is installed, you have to restart
Firefox.

Then, go to the ScienceBlogs
home page.  Find the search box in the left sidebar.
 Right-click in the search box.  The little menu
(context menu) that pops up will have an item in it: “Add to search
bar…”  Select that, and you are all set.  

Then, anytime you want to see whether a ScienceBlogger has posted on a
particular topic, you can select the SB search engine and do the
search, regardless of what page you happen to be looking at.  

An added bonus: If the SB search engine is the one that is active, you
can highlight any text on any page, right-click, and select “search
ScienceBlogs for…”

Curious about the Mesozoic Cow?  Itching to see the best photo
in the world of the Roseate Skimmer?  Now it is simple.