This is pretty much spot on, but email me with any corrections
*

Riff 1
G -------------------
D -------------------
A --------------3-5--
E 5--5--5--5-5-------

This is played over the verses and for the intro...

Riff 2
G ---------------------------
D 5--5-4--4------------------
A ----------7--7-5--5--3-5---
E ---------------------------
             ...I wanna new bird,
                yeah gimme a new bird etc..

This is the descending run played over the chorus


Riff 3
G ----5-57--5-75---
D 7757-7-----7--75-   This is the fast bit in the bridge, it repeated 
A -----------------   a number of times, then played an octave higher
E -----------------   starting on the 19th fret of the D string.

That's it, listen to a recording to get a feel for the timing and structure.