Amazon appears to have been the big winner in picking up former Borders customers. According to new figures from Bowker Market Research, Amazon’s share of book spending in the first quarter of 2012 was 29%, up from 23% in the comparable period in 2011. Barnes & Noble’s share of spending, in second place, rose to 20%, from 19%, with the gain coming from B&N’s stores as BN.com’s share of spending held even at 3%. In the first quarter of 2011, Borders held a 10% share of spending.

Online retailers besides Amazon and BN.com held the third-largest market share in the quarter, capturing 10% of spending, up from 7% in the first quarter of 2011. Independents’ share of spending slipped to 6% from 9% in last year’s first period.

In addition to the collapse of Borders, the other key factor behind the shift in buying patterns was the increased sales of e-books and lower sales of print books. The trend clearly benefited Amazon and the other e-tailers that include Apple, and also helps explain the decline in market share at indies, who still have low e-book sales.

According to Bowker, e-books’ share of spending in the first quarter of 2012 rose to 10%, up from 6% in 2011’s first quarter. In a somewhat surprising finding, the data show that e-books’ share of spending came entirely from the trade paperback format, whose share of total spending fell to 33% from 37%. Hardcovers’ share of spending rose slightly year-over-year, while mass market paperbacks’ share held even at 7%.

In the first quarter of 2012, Bowker found that 64% of e-book spending was done by women, while the age group where e-book spending had the biggest impact was 18-to-29-year-olds, who accounted for 31% of all e-book spending in the quarter. The next oldest age group, 30-to-44-year-olds, was slightly behind, accounting for 28% of spending on e-books. Teens 13 to 17 spent the fewest dollars on e-books, with the age bracket representing only 5% of e-book sales. Measured by household income, book buyers in households with income between $50,000 and $74,999 accounted for 23% of e-book spending in the quarter, while readers in the $75,000 to $99,999 range accounted for 20% of e-book spending.

The data were drawn from Bowker Market Research’s PubTrack Consumer Survey. In early August, the newest edition of Bowker’s annual review, which features a complete analysis of 2011 trends, will be published. More information on the report is available by contacting MarketResearch@bowker.com.