I have written the following in other posts, namely creating a repertoire and in Bird repertoire.
"vs 1.f4
I suggest 1...c5 or 1...d5 I play both. With 1...c5 expect the game to turn into a grand prix sicilian or a closed sicilian and both are fine for Black since I dont know that white may have anything more promising for him.
With 1....d5 Expect a dutch with colors reversed and study accordingly, but pay very close attention to move orders. I can explain this more later if you are interested.
Personally I have a taste for 1... c5 and 1... d5. With 1... c5 Black can hope for play to transpose in some cases to a Grand Prix version of the Sicilian. In other cases, he will be able to play a botvinnik set up ( english) with colors reversed, another solid choice. --- In response to this, HgMan wrote, In response to Bladez, playing 1 ... c5 and hoping for a Grand Prix is ridiculous: why would White play 1 f4 in order to play an inferior Sicilian? When an opponent is faced with this OTB, the Bird can present some unsettling problems, and it's been my experience that Fritz and other engines tend to overestimate Black's chances (which has proved to provide some nice results in correspondence chess)"
So it is really nice to see that in books and in this forum, other people are stating they know about this fact (since it was never just an opinion)."