Brazil has the Tomas Sigrist books - of which there are several versions which all leverage the same work. There is a large "An artistic view" coffee table book, which is lovely in my opinion but weighs about 6kg, honestly. There are the generally out of stock / only in Portuguese / generally unavailable out of Brazil actual field guides. I speak enough Portuguese to use a field guide just fine but I've still yet to be able to connect with one - hopefully at some point. I just rechecked the website and there is a miniscule pocket guide available at the moment, FWIW, the Guia do Bolso on this page:
http://www.avisbrasilis.com.br/livros/tomas-sigrist.html
There is the widely available Ber van Perlo book which is, as far as I know, one of only two full coverage books, and it is the most modern and nominally the best. It is definitely better than the Ber van Perlo Mexico and Central America book, but I can't really get excited about it, it is a very poor guide with inadequate art (with many errors), and woefully inadequate text.
There are the two new Wildlife Conservation Society volumes - Pantanal and Atlantic Rainforest - that leverage prior Ridgely and Tudor work. These are fantastic but only cover a portion of Brazil, and I've heard that it is unlikely that the hoped for 3rd-5th volumes will materialize. If the Amazonian volume were to come to fruition it would be wonderful, but I am not terribly hopeful.
There is also the older Deodata de Souza "All the Birds of Brazil." I don't own it but have seen it, and I would put it a step behind the van Perlo book, based on the bit I've looked at it. I don't know if it's still in print and available?
As well, there are one or two large works underway, that I know of. First, the Zimmer / Whittaker guide - above you comment that it's due next year but are you certain of that? It's 10+ years in and I haven't seen or heard of a fixed publication date elsewhere. This guide should be fantastic when it finally arrives. As well I know that at least previously Brett Whitney was working on a guide or series of guides but I haven't heard anything about it in so long that I don't know if it's still underway or not.
Over to Argentina, the Pearman book is something like 15-20 years underway, original publication dates were 2003 or 2006 or some such? I am certain it will be authoritative and brilliant when it finally publishes.
The Bolivia guide is, in my opinion, fantastic. I was fortunate to be in La Paz just as the first copies became available, and it is a tremendous contribution to South American field guides. I know everyone is hoping it will become more widely available in the future.
Along those lines, Miles McMullen's small guides for Colombia and Ecuador are really quite good, particularly considering size, and it's a shame they're not more widely available. Actually, I am guessing many here aren't aware, Miles is working on a third edition of the Colombia guide that should publish shortly. It was available for pre-order via Indiegogo - link here:
https://www.indiegogo.com/projects/field-guide-to-the-birds-of-colombia#/