Bird Variation

The Bird Variation, usually called Bird's Defense, abandons the protection of e5 and instead offers a knight trade that drags a black pawn to d4. White almost always accepts with 4. Nxd4 exd4. The advanced pawn takes space and hampers White's queenside, since c3 and Nc3 become awkward, but Black is left with doubled d-pawns and trails in development. White normally castles and closes the center with d3. One recommended line is 5. O-O Bc5 6. d3 c6 7. Ba4 Ne7, which leaves White with a slight edge in engine terms. The Paulsen Variation, 5. O-O Ne7, develops the knight first. The rarer 4. Bc4 retreats the bishop onto the f7 diagonal, and Black typically answers 4...Nxf3 5. Qxf3.

The defense appeared in Bilguer's Handbuch in 1843 and takes its name from Henry Bird, who adopted it often in the late nineteenth century with an overall minus score. Tarrasch, Spassky and Khalifman tried it occasionally. It now serves mainly as a surprise weapon. Magnus Carlsen lost with it against Ivan Šarić at the 2014 Olympiad.