Beautifully written and very moving. Among other things, it's a psychological thriller and an adventure story (i.e., following some of the remaining Arctic terns on their migration to Antarctica). Despite the book's restless, haunted narrator and its focus on mass extinction, it did not leave me feeling bleak. It raises important questions about what humans owe to the creatures with whom we share the planet, and those concerns are presented in an energizing way.

There are a lot of memorable, thought-provoking passages. For example, this one really jumped out at me: "I think of the impact of a life like that. It sounds quiet, and so small as to be invisible. ... But I know better than that. A life's impact can be measured by what it gives and what it leaves behind, but it can also be measured by what it steals from the world."

I thoroughly enjoyed it. I did about 50-50 reading and listening to the audiobook, and the narration by Barrie Kreinik was great.