The brown back is not that evident in this photo but it is the only mockingbird in the region (said my resources at the time). Later I decided that this could be a Patagonian Mockingbird. These are best differentiated by the tail, which is not that clear in this photo, but may be just white-tipped consistent with Patagonian. Also the bird was in a scrub area, while the Brown-backed Mockingbirds I saw were in more forested areas and in tall trees.
Africa (entire continent rather than south of Sahara)
AN
Antarctica
AO
Atlantic Ocean
AU
Australasia (Wallacea (Indonesian islands east of Wallace's line), New Guinea and its islands, Australia, New Zealand and its subantarctic islands, the Solomons, New Caledonia, and Vanuatu)
PAL
Eurasia (Europe, Asia from the Middle East through central Asia north of the Himalayas, Siberia and northern China to Japan)
IO
Indian Ocean
LA
Latin America (Middle and South America)
MA
Middle America (Mexico through Panama)
NA
North America (includes the Caribbean)
NO
Northern oceans
OR
Oriental Region (South Asia from Pakistan to Taiwan, plus Southeast Asia, the Philippines, and Greater Sundas)