Watch Nature Season 32 Episode 5 Online

There is an unusual looking monkey called the crested black macaque that is endemic to rainforests in Indonesia, which includes the island of Sulawesi. These striking black primates, sporting punk hairstyles and copper-colored eyes, first caught the attention and won the heart of wildlife cameraman and biologist Colin Stafford-Johnson 25 years ago. But since then, their numbers have dropped by almost 90 percent, so the filmmaker returns to the island to discover why and how he could help.