Amazon. Field Guide to the Birds of Machu Picchu, Peru by Barry Walker; illustrated by Jon Fjeldsa. Published by the Peruvian National Trust for Parks and Protected Areas.
Bird Diversity in the Machu Picchu Historical Sanctuary by Barry Walker. Apparently some 423 species have been recorded at Machu Picchu, apparently a high count considering. The article is interesting, even if you're not a birder, with much on species conservation near Machu Picchu and neighboring Peru. The following argument is interesting if true:
"It is no coincidence that areas with a high count of endemic birds and a great diversity are often close to densely populated areas and centers of past high cultures such as the Incas. The special environmental conditions and benign climates which protected relict bird species may also have facilitated the development of human populations in the Andes."