#schrodigirl

 According to the North American instruction manual of Super Mario Bros. 2 (pg. 27):

He thinks he is a girl and he spits eggs from his mouth. He'd rather be called "birdetta"

This statement applies to all translations of the title. Throughout the official guide, Birdo is also consistently referred to as a "he". In Japan, Birdo is portrayed as a male who believes she is a female and prefers to be called by a nickname, "Cathy", rather than her real name "Catherine". As recently as Super Smash Bros. Brawl, Birdo's trophy description describes the character as "gender indeterminate", and uses the pronoun "it" rather than gender-specific pronouns such as "he" or "she", which has sometimes been used in other occurrences.

However, Nintendo of America usually refer to Birdo as female. The feminity of Birdo is implied in Mario Kart 8, where she appears on "Women of Racing Organization" advertisements in N64 Royal Raceway, and in Sunshine Airport, the person in the speaker calls her "Ms. Birdo". This is contradicted clearly in the British English version of Mario Tennis Aces, where the Toad commentators use masculine pronouns to refer to Birdo, as well as in the British English version of Super Mario Party.

The confusion surrounding Birdo's gender has also been addressed in a light-hearted matter, such as when Popple pauses before settling on calling Birdo a "dame" in Mario & Luigi: Superstar Saga, and is also shown in the U.S. manual of Mario Golf: Toadstool Tour, where all the female characters have a pink dot behind them, including Birdo. In Paper Mario: Sticker Star, the first two lyrics of Birdo's serenade alludes to the gender confusion by saying Heart of a woman, heart of a man.... Both can know of love's grace.....