I took these at the Darwin research station on Santa Cruz on 26 July 2008. Both photos are of the same bird.
The bird was by itself in a tortoise enclosure. Our local guide called it a Medium Ground-Finch, but when I asked him to look at it again (after it had flown into a tree) he agreed that it was a Large Ground-Finch. Since then one correspondent has said he thinks it was likely a Medium Ground-Finch.
All I can say is that its bill was bigger than any of the many Medium Ground-Finches I saw on this trip.
Please advise. Thank you.