With the grace of a ballerina and the timing of an opera diva, Carly the cougar pads into her den. Behind the scenes at Northwest Trek Wildlife Park, the den has a mesh wall with a waist-high perch on one side, where keeper Haley Withers is waiting patiently outside with some meatballs. “Come on, girl,” she calls softly. Carly pauses. Looks the scene over. Then in one swift movement she’s up on the perch, positioning her tail near a small horizontal opening. It’s cougar-training time. Trust me – just hold still “To train any animal, you need their trust,” says …