I had just returned from a 19 day tour of Peru when I purchased this set. On the tour we had relied upon The Birds of Peru (Princeton) which was good. However, as I examined my photos of some hard to identify birds, a few defeated identification until I consulted the plates of the new two volume set. Success! The plates in Birds of Northern South America are worth the price of purchase alone! They feature paintings of subspecies and plumages not available in other common publications. If you're going to seriously bird Peru you will need these two volumes. Sturdy and well printed, but heavy. Chris Siddle, Vernon, B.C.