Kindle Fire

According to numbers posted Friday on GalleyCat, sales from eBooks in the first quarter of 2012 topped hardcover sales.

Jason Boog at GalleyCat writes that the sales report from the March Association of American Publishers indicates that net sales revenue from adult eBooks were $282.3 million; hardcover sales, $229.6 million. Last year, during the same period, hardcovers raked in $335 million; eBooks, only $220.4 million.

What’s the cause of the spike? Lauren Indvik writes at Mashable that “the proliferation of ereading devices, from tablets and smartphones to dedicated ereaders, has a lot to do with it.” She cites research published by Pew Research Center in April that “found a strong correlation between the spike in sales of ereading-capable devices and ebook adoption over the holidays.”

Chart from GalleyCat

Notably, Indvik points out in her blog post, downloadable audiobook sales have outpaced eBooks, up 32.7% to $25 million during the first quarter.