Arlington’s Library Director Ryan Livergood will honor a promise to dress up as Clifford the Big Red Dog after Somerville beat Arlington in a library card sign-up challenge. Somerville’s public libraries will also claim platters of baked goods from Arlington, Belmont, and Lexington bakeries after winning the month-long competition in February. Arlington challenged the other communities to see which could get the highest percentage increase in new library card registrations for the month of February 2013 over February 2012 totals. Somerville won big, increasing registrations by 320 percent. Belmont finished second with an increase of 186 percent, and Arlington finished third, increasing registrations by 183 percent. Livergood will follow through on his pledge to visit the winning community dressed as Clifford the Big Red Dog, but the details of his visit to the Somerville Public Library have not yet been announced. In a press release announcing the results, Livergood said there were no losers in the competition, which successfully promoted the value of library cards and services offered by libraries.