Overall sales of tablets fell 14.7 percent in the first quarter to 39.6 million units, continuing a downward trend from 2015 when the once-hot market cooled, said the survey by research firm IDC.
Apple remained the top seller with a 25.9 percent market share, even though its iPad sales slumped 18.8 percent from a year ago, IDC said.
Samsung held the number two spot with a 15.2 percent market share, even as sales tumbled 28 percent.
Amazon jumped to number three, as its low-cost Fire tablets at prices as low at $50, saw a surge in sales.
While Amazon does not publish sales figures, IDC estimated it sold 2.2 million tablets in the quarter, a leap of 5,400 percent from a year ago, giving Amazon a 5.7 percent market share.
IDC said the "slate" tablet still accounted for 87.6 percent of the market in the past quarter but that sales of laptops with detachable tablets more than doubled to 4.9 million units.
"The introduction of detachables from traditional smartphone vendors is only beginning and pose a real threat to traditional PC manufacturers," said Jean Philippe Bouchard, research director for tablets at IDC.
"Their understanding of the mobile ecosystem and the volume achieved on their smartphone product lines will allow them to aggressively compete for this new computing segment. It is likely that those smartphone vendors will utilize the detachable segment to create new mobile computing end-user experiences if customers are using their detachables in combination with their smartphones."
The relatively strong performance by Apple was helped by the introduction of the iPad Pro 9.7-inch model, one of the new tablets with detachable keyboards, as well as a price drop for the iPad Air 2, the report said.
"Microsoft arguably created the market for detachable tablets with the launch of their Surface line of products," said IDC analyst Jitesh Ubrani.
"With the PC industry in decline, the detachable market stands to benefit as consumers and enterprises seek to replace their aging PCs with detachables. Apple's recent foray into this segment has garnered them an impressive lead in the short term, although continued long-term success may prove challenging."