A rare first edition of John James Audobon's "The Birds of America" with life-size portrayals of more than 400 North American species was sold for $7.9 million at a Christie's auction in New York on Friday.

The book, expected to fetch more than $7 million, was put on sale by the heir of the fourth Duke of Portland, who had bought it around 1838.

The buyer of the book, an American whom Christie's has not identified, bid over the phone, according to The Associated Press via aikenstandard.com.

In December 2010, a first edition of "The Birds of America," was sold at Sotheby's in London for $11.5 million.

There are only 120 complete editions of the book, and most of them are held by institutions.