How do you get bigfoot out of his cage?

Get close to Gretchen's copter, then jump across to it, pull out her fuel tank cap which is a bit past the door of Gretchen's copter, and jump down to the Bigfoot cage. Cut the rope with your shears and you safely drift down on the cage's parachute. You have won the island! Unfortunately, Mews is broke, so you donate your million dollars to set up a Bigfoot refuge at the caves.