An interesting new paper in the journal Primates documents how a group of chimpanzees in Bossou, Guinea have been successfully deactivating snares set by human bushmeat hunters. Though not always successful, the scientists observed the behavior in five juvenile to adult males. Compared to the rate of injuries from snares to chimps--which aren't the target of these hunters, it should be noted--across Africa as a whole, this group in Guinea has remarkably lower casualties.

To deactivate the snares, which generally consist of a loop of iron wire connected by a vine rope to a nearby sapling, the chimps grasp the snare stick with their hands and shake it until the snare breaks. Other times the chimps knock the sapling before having a go at the snare stick. However, in all cases the chimps avoid touching the wire loop, which they apparently know is the dangerous part.

In the discussion part of the paper, the researchers note,
Snare deactivation by chimpanzees has not been observed at other study sites. This presents a puzzle, because snare injuries continue to be a problem threatening these animals across Africa. One possible explanation for its occurrence at Bossou is the long history during which chimpanzees and humans have coexisted. Long-term exposure to snares may have allowed Bossou chimpanzees to learn about the dangers associated with them, and possibly how to interact safely with and eventually deactivate them.
Read the original paper, which goes into detail of each observed interaction; it's pretty fascinating: Deactivation of snares by wild chimpanzees [PDF]