From the Origin, second edition, pp. 73-74:
And I was listening to Off Track and that again reminded me of it. It was one of those delight full snap moments when life puts one card on top of another and there is lovely fit. The program is "Native Like a Fox" and it is well worth a listen. It poses the challenging question of when does the introduced pest become native and when does the native become a pest, and it relates it to the links in the food chain. Nice. Here's the link.