BBC: Saving California's butterflies

In California, butterflies such as the monarch are critically endangered as a result of habitat erosion, pesticides, and climate change. But many people are trying to save these beautiful insects.

We meet the scientists who are painstakingly rearing individual butterflies by hand and then releasing them back into the wild. In California’s vineyards, we talk to a farmer who has designed a butterfly-friendly tractor. And at the famous butterfly groves on the coast, we see the first signs of recovery.