Happy, who taught researchers that elephants can recognize themselves, is euthanized at Bronx Zoo

Happy, a 55-year-old Bronx Zoo elephant who lived there nearly 50 years, was euthanized after age-related health decline, leaving Patty as the last elephant on exhibit in New York City.
In 2005 Happy helped show elephants can recognize themselves in a mirror—touching an "X" on her head—a rare sign of self-awareness.
Keepers remember her playful habits (she loved watermelon and strawberries and sometimes stashed treats in her ear) and called her a beloved ambassador for elephants.