Birdo, known in Japan as Catherine (キャサリン, Kyasarin?), is an enemy to Mario and playable character in various games. Birdo first appeared in the Japanese game Yume Kōjō: Doki Doki Panic and the remade Super Mario Bros. 2 as a recurring boss, misnamed "Ostro" (which is really the ostrich enemy; the game labels Ostro as Birdo and vice versa; this has been corrected in Super Mario Advance). Birdo later appeared in Wario's Woods as an ally of Toad, Super Mario RPG: Legend of the Seven Stars as a boss character, and in Mario & Luigi: Superstar Saga, as a boss paired with the thief Popple. Birdo was first playable in the Nintendo 64 installment of Mario Tennis, as Yoshi's partner. Since then, Birdo appears as a playable character in several Mario sports titles and in the Mario Party and Mario Kart series.
Birdo's gender has changed throughout various American game versions, but has always been male in Japan. In the original manual for Super Mario Bros. 2, Birdo is referred to as male that believes he is female, and would like to be called Birdetta. Most later American-localized games, such as the Mario sports titles, which have featured Birdo with a diamond ring, have usually listed Birdo as a female. Recent localizations have avoided the use of any gender pronouns when describing Birdo. In Super Smash Bros. Brawl, it is said that Birdo is of "indeterminate gender" in its trophy.
In addition, the trailer for the Wii game Captain Rainbow is narrated by Birdo using a distinctly male voice. However, reviews have stated that part of the plot surrounding the Birdo character is gender related and involves proving its womanhood. In Super Mario Advance, Birdo is wearing a bow and can be green or pink.
I guess Nintendo is trying to gain new ground (and somehow without being noticed by the torch and pitchfork wielding super conservatives out there) this is cool I guess, but I can't take it serious.
(Oh also the pic is from this)