Bird's Opening and the Dutch Defense A naturally positional class-C player (c. Elo 1500), I have learned in recent years to push my f-pawn two squares early in the opening, to force myself to play tactical chess.  The King's Gambit (which I had never tried until three years ago) surprises me in how often it unnerves my black opponent:  I have won more games with it than I should have thought possible, mostly because of my opponents' blunders.  Even against the Sicilian, 3. f4 has proved an interesting move though it lacks the sheer psychological impact of the King's Gambit.  With the black men, I have been trying the Dutch Defense 1. d4 f5.  I have been losing, but I have been trying it, and eventually I hope to figure the Dutch out.

My question therefore is this.  If f4and f5 are such interesting moves in the opening, then why should Bird's Opening 1. f4 be so much less common than the Dutch Defense 1... f5?  Is it only because the King's Gambit is better than Bird's, or is there some other reason?

To be clear, my question today is not whether pushing the f-pawn two spaces is wise or fundamentally sound.  Believe me, having tried it over and over during recent years, I have learned a lot of ways to lose by pushing that pawn!  My question regards rather, among aggressive players who will push the f-pawn, why black tends to push the pawn earlier than white does.  Given the increased risk black runs by pushing the f-pawn at the disadvantage of a tempo, one would think that white, not black, would be the leading f-pusher -- whereas 365chess.com has 1. f4 in 0.6 percent of all games, compared against 1... f5 in 3.6 percent of games that have begun 1. d4.

In light of the relative popularity of the Dutch, why should Bird's Opening be relatively so uncommon?
Good question, and to understand the differences, we have to first discuss "reversed" openings.

The most common example of a reversed opening is the King's Indian Attack (1. Nf3 2. g3 3. Bg2 4. O-O 5. d3).  Compare that to the King's Indian Defense (1... Nf6 2... g6 3... Bg7 4... O-O 5... d6).  The only major difference between the following two positions is which "side" has the move: 

King's Indian Defense

[title "White to move"]
[fen "rnbq1rk1/ppp1ppbp/3p1np1/8/2PPP3/2N2N2/PP3PPP/R1BQKB1R w - - 0 1"]


King's Indian Attack:  

[title "White to move"]
[fen "r1bqkb1r/pp3ppp/2n2n2/2ppp3/8/3P1NP1/PPP1PPBP/RNBQ1RK1 w - - 0 1"]


In the second diagram, white has a full extra tempo over black in the first diagram.  However, this extra tempo is not so useful.  Depending on what white does, black will adopt various formations to nullify white's extra move.  In the first diagram, black can wait to see how white develops before committing.

In fact, Bobby Fischer said (somewhat tongue in cheek) that in the following symmetrical position, black has the edge:  

[title "White to move"]
[fen "rnbq1rk1/ppp1ppbp/3p1np1/8/8/3P1NP1/PPP1PPBP/RNBQ1RK1 w - - 0 1"]

1. ( 1. c4 e5) e4  c5


If white plays 6. e4, then black will respond with 6... c5, but if white plays 6. c4, then black will play 6... e5, in both cases leading to a fighting game.  

So with that lengthy introduction, now we can look at the Bird.  To begin, after 1. f4, black can immediately strike with From's Gambit: 1... e5! when black scores incredibly well (49.5% from the link in EdDean's answer).  White's best might be to transpose to a King's Gambit with 2. e4.  

Furthermore, black will again have an edge that white usually does not have in the Dutch - the ability to see how white develops and then react accordingly.  White can certainly play a quiet system like 1. f4 2. Nf3 3. e3 4. d4 5. c3 and play with that color complex, but if white does that, he is squandering his first move advantage and can claim only equality.  

If white tries an enterprising system like the Leningrad Dutch (1. f4 2. g3 3. Nf3 4. Bg2 5. O-O 6. d3 with the plan to play e4), then black will have the opportunity to strike back with h7-h5-h4 when white will have to defend against a fairly vicious attack.  In the Dutch there are various ways to avoid this plan from white although they are beyond the scope of this question.  

Hopefully this gives you a bit of an introduction to not only the differences between the Bird and the Dutch, but also how to evaluate reversed openings.