Mayor Bill de Blasio weighed in on Happy the elephant Friday.

Hizzoner expressed sympathy with the animal rights activists who want to move the pachyderm out of isolation at the Bronx Zoo and into an elephant sanctuary.

“I understand why they’re concerned,” de Blasio said on WNYC radio. “There’s a reason that social animals might be deeply affected by that experience.”

Happy has lived at the zoo since 1977. Activists with the Nonhuman Rights Project argue that the 48-year-old pachyderm’s “liberty is being violated” by her cramped, lonely quarters and they want her relocated to the Performing Animal Welfare Society Wildlife Sanctuary in California or a similar facility in Tennessee.

The group’s spokeswoman, Lauren Choplin, applauded de Blasio for “recognizing the social needs of elephants.”

Hizzoner admitted that although he’s visited the zoo, he’s doesn’t remember “ever being there to see [Happy] myself.

“I don’t know enough about the details, but I sure do know that a lot of people are concerned,” he said.

De Blasio said he wants to “hear from the folks at the Bronx Zoo … What is their argument about what would happen if that elephant is released.

“I have not gotten a clear answer on that one,” he said.

Reps for the zoo did not immediately return messages, but in the past they’ve said Happy is perfectly pleased with her surroundings and that moving her would cause her harm.

Choplin disagreed.

“We see the Bronx Zoo as engaging in some fear-mongering on that point,” she said.

“All the evidence suggests that elephants, including ones like Happy that have been alone for so long, would thrive in a sanctuary,” Choplin said.