A new lawsuit charges that the Bronx Zoo has "unlawfully imprisoned" its 47-year-old Asian elephant, Happy, forcing the majestic and behaviorally complex beast to live a life of soul-crushing solitude.

The suit, filed by the Nonhuman Rights Project on Tuesday, demands recognition of Happy's legal personhood and right to bodily liberty, and calls for her to be transferred to an animal sanctuary. Bronx Zoo director Jim Breheny and the Wildlife Conservation Society are named as defendants, for allegedly keeping Happy in isolation and not giving her adequate space to roam.

"Our world-class experts say that, like all elephants, Happy is an autonomous being who evolved to walk 20 or more miles a day as a member of a multi-generational large social group," Steven M. Wise, founder and president of the NhRP, said in a statement. "The entirety of the zoo’s elephant exhibit provides far less than even one percent of the space she would roam in a single day in the wild. She doesn’t belong to a social group. Her autonomy is thwarted daily. This has got to stop."

The habeas corpus petition is the first legal action taken on behalf of Happy, who for years has been considered the zoo's loneliest elephant. While elephants in the wild develop lifelong attachments with family members, and those in captivity are typically given companions, Happy has been living alone for more than a decade.

For much of her life, Happy did have a partner—Grumpy, another Asian elephant who was captured along with five other calves in the 1970s, and eventually landed with Happy in the Bronx. But the zoo's two other remaining elephants, Maxine and Patty, charged Grumpy in 2002, fatally injuring her and leaving Happy all alone. Happy was then briefly paired with a young elephant named Sammy, who soon after contracted a liver disease and was euthanized—the zoo's third elephant death in just four years, according to the Times.

In the past, animal advocacy groups have accused the Bronx Zoo of mistreating its elephants, citing cold winters and cramped cages, as well as Happy's isolation. But the zoo has countered that Happy shows "no signs of physiological or psychological stress," and maintains a close bond with her caretakers. Abruptly severing that bond by sending Happy to an animal sanctuary could be traumatic, according to the zoo's conservationists.

"The Nonhuman Rights Project is exploiting the Bronx Zoo elephants to advance their own failing cause in the courts as they put forth ludicrous legal arguments and lies about our elephants, facilities and staff," Bronx Zoo Director Jim Breheny said in a statement to Gothamist.

The animal advocacy group—which has filed similar petitions on behalf of chimpanzees—notes that Happy is a particularly intelligent pachyderm. She was the first elephant to ever demonstrate a sophisticated degree of self-awareness, after passing a mirror self-recognition test in 2005. A year later, the zoo announced that it would be ending the elephant exhibit once one or two of the animals died—admitting that it would be inhumane to sustain the exhibit with just one animal, or two that didn't get along.

When that does happen, it will be the first time that New York City is without a single full time elephant resident in more than a century.