I wasn't satisfied with my Firebird and Thunderbird icons being otherwise exactly the same but only with different colors so I remade the Firebird one to be more of my liking. Hope you like it too.
Maybe I should next remake the Thunderbird icon to match Firebird's.
Oh yeah, almost forgot: I used pim's iconset as background and simply cut the birdie's head from Firebird's about box.
Not very difficult, but me likes the result ^^