http://youtu.be/kaS_pVAODjU The Cross River gorillas are an elusive bunch: there are fewer 250 individuals left of this western gorilla subspecies, and, understandably, they are afraid of humans. A few hours ago, though, the Wildlife Conservation Society announced that they'd managed to capture a tape of 8 gorillas---about 3% of the remaining population---in their native Cameroonian habitat, by using a motion-activated camera. It's a fascinating glimpse into the behavior of an animal that, given current trends, more than likely won't exist in the near future. Lumbering on their knuckles through the crackling leaves, the gorillas occasionally plunk themselves down under a tree before continuing on their journey. About half-way through the edited clip, a large male gorilla charges past the camera, striking his chest with cupped hands, a motion that produces a high, distinctive, almost yodeling sound, and as he falls back on all fours, you can see the silver hair on his back. Shortly afterward, a gorilla missing its left hand moves across the scene; WCS thinks the hand could have been lost to a poacher's snare. It seems, though, that the ululating sound threw a few people off. CBS News' coverage is studded with some choice work-arounds demonstrating that they're not really sure what that was: the headline "World's rarest gorilla makes unexpected noise with chest" is a good one, though I'm also partial to the video caption "a male gorilla making a bizarre popping sound."