When the Wolves Returned: Restoring Nature's Balance in Yellowstone by Dorothy Hinshaw Patent; photographs by Dan Hartman and Cassie Hartman (Walker, 2008).
The Wolves Are Back by Jean Craighead George; paintings by Wendell Minor (Dutton, 2008).
These two nonfiction picture books cover the same topic in very different, equally effective ways. We have a soft spot for wolves; so we read both of them.
When the Wolves Returned is illustrated with historical and contemporary photographs of the park, its human visitors and its wild inhabitants. Patent's text is dual-level: one sentence in large type on the left hand page, a more detailed paragraph in smaller type on the right. Back matter includes a note about the photographs, a bibliography, and an index; there is also a diagram of "The Wolf Effect" that tests your memory of how the wolves' return has impacted other plants and animals at Yellowstone.
The Wolves Are Back is illustrated with Wendell Minor's realistic watercolor-and-gouache paintings. George's text tells the story of Yellowstone's wolves in the context of one wolf pup's adventures (not surprisingly; George is a novelist, author of the Newbery Award-winning Julie of the Wolves); it is more poetic, punctuated by the refrain "The wolves are back." There is no back matter apart from the artist's list of sources.
I think these two books--these two types of books--are complements rather than substitutes. I was interested in which type of book appealed most to which of my kids (I had some ideas, although they both generally prefer fiction to nonfiction read-alouds); but there was no comparison: the kids saw them as two different, equally appealing books.