By Ana Norman Bermúdez PHUKET, Thailand — The air is thick and sticky in the forest surrounding the Gibbon Rehabilitation Project center. Thanaphat Payakkaporn, head of the project, bends down to pick up the discarded shells of langsat fruits, a sign that wild gibbons have been in the area. As a series of loud, melodic whoops echo through the jungle, Thanaphat looks up at the canopy and smiles. “Bo’s son comes to visit him sometimes,” he says. Bo is a 37-year-old white-handed gibbon (Hylobates lar), rescued in 1993 after being captured and kept as a pet for five years. He’s one of around 400 g…