After increasing at a 169% rate in the first two months of 2011, e-book sale rose at a relatively modest 145.7% clip in March, to $69 million, according to the 16 publishers who report figures to AAP’s monthly sales estimates. For the first quarter of 2011, e-book sales were up 159.8%, to $233.1 million. While adult hardcover and mass market paperback did better, posting gains in March, all the print segments had declines for the first quarter with the nine mass market houses that report results showing a 23.4% sales decline, and the 14 children’s paperback publishers had a 24.1% decline in the quarter. E-book sales easily outdistanced mass market paperback sales in the first quarter with mass market sales falling to $123.3 million compared to e-books’ $233.1 million in sales.

In other segments, the 18 religion book publishers who report results had a 27.4% sales gain in March and were up 13.7% for the quarter. Physical audiobook sales were down 11.8% for the month and 17.6% for the quarter, falling to $21.8 million at the 20 reporting companies. Digital audiobook sales rose 9.0% in the quarter at the 14 reporting companies, and just trailed traditional audio with sales of $20.2 million