That's the same source I found for the quotation when I hit up the search engines, but I was rather hoping for a naturalist of some description to back up the theory. I don't see that you could be confident of that explanation without some amount of field work. Who put in the eye-hours to develop and confirm this hypothesis?

Edit: I mean, if Eb the author did, that's fine, but he doesn't even mention growing up in the country.