More air travelers are choosing to check bags despite the often hefty added costs. The Department of Transportation said Friday that U.S. airlines collected more in checked baggage fees in the first three months of this year, even as the number of travelers went down from peak holiday travel times. The nation's 17 largest airlines collected $815.8 million in baggage fees during the first quarter, up 3% from the fourth quarter of 2011. The increase came despite a 4% drop in traffic between the two periods. The fourth-quarter, which includes peak Thanksgiving and Christmas travel periods, is generally the next-busiest quarter for air travel after summer. Compared with the first-quarter of 2011, bag fees in the first three months of the year rose 4%. Traffic between those periods fell 3%. Airlines collected $631 million in fees for reservation changes in the first quarter, compared with $597.8 million in last year's first quarter and $567.1 million in the fourth quarter. Baggage fees and reservation change fees are the only added charges that DOT breaks out.