What are bisexuals taking part in the LGBT pride parade are celebrating?
Tucson Pride:  Tucson Pride organizes and promotes the greater Tucson metropolitan areas LGBT pride parade ("Pride on Parade") and pride festival ("Pride in the Desert") which are currently held at the start of October each year in Tucson, Arizona, to celebrate the lesbian, gay, bisexual, and transgender (LGBT) community and their allies. Bisexuality: Bisexuality is romantic attraction, sexual attraction, or sexual behavior toward both males and females, or romantic or sexual attraction to people of any sex or gender identity; this latter aspect is sometimes alternatively termed "pansexuality."
romantic attraction, sexual attraction, or sexual behavior toward both males and females