The February US search market share numbers are out from comScore. It appears that a portion of the gains that Yahoo made since November as a result of its default search deal with Firefox have been lost as some number of users return to Google.

Google has been actively lobbying Firefox users to switch back for the past couple of months. More recently the company has become increasingly aggressive in trying to lure back users. While somewhat successful, so far Firefox users haven’t switched back en masse.

According to comScore Yahoo lost roughly 10 percent of its search query volume between January and February. Google gained a tenth of a point and so did Bing, which is where the Yahoo volumes went. StatCounter also showed a similar, directional loss of share by Yahoo from January to February.

US search market share (Dec – Feb)

Source: StatCounter (3/15)

From December to January Yahoo had gained 1.2 points, largely at Google’s expense. It has now given back 0.2 percent of those gains. It remains to be seen how much more will return to Google as a result of “switchbacks.”

The numbers above don’t take into account mobile search, where Google is even more dominant than on the PC.

The industry is awaiting the outcome of the rumored “search bake-off” going on for Apple’s default Safari business. I predicted last week that Google and Apple would not renew their deal, with Google potentially banking on a switchback scenario for Safari users as well.