Sometimes I start out to write about a particular story and then, while researching, discover an angle that really makes me stop and think.

This time, I was going to write about how people are finding ways to use invasive species, or to create jobs and work while removing them – as a brilliant South African program called Working for Water has done for many years, removing non-native trees that use up large amounts of scarce groundwater.

And then I came across the Torrey Guardians and became fascinated, both about their work and about the issue it raises as global warming alters our climate. Do we relocate species if they are endangered, even if it means putting them into another habitat? What does it mean if we move a species into a habitat where it’s not native? And what, in a time of climate change, is a native habitat anyway?