Corwin’s documentary, which cost about $2 million to produce, spawned from a book, also called 100 Heartbeats, which was released in late October and was about two-thirds complete when he pitched MSNBC. The filming was often arduous, Corwin said, but “the hardest part was looking at all the footage that didn’t make it in.”

Fortunately, some of that extra tape found a home on the Future Earth Web site. There, for example, viewers can watch the story of Chhouk, a Cambodian elephant that lost the lower half of one of its legs in poacher’s snare, but received a prosthetic from local conservationists that may have saved its life.

Not all tales have happy endings, however. Corwin said that since he completed filming, timber companies have purchased the jungle sanctuary to which he’d helped transfer a group of Sumatran orangutans. “Unfortunately,” he said, “these types of stories are not going away.”

The film and the book repeatedly stress that humans are responsible for the extinction crisis, and only they have the power to stop it. Clearly, the last thing Corwin wants is for his next documentary to be called 50 Heartbeats.

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.