In recent interviews, Sibley has stated that he created this guide with birders in mind and hopes that it will help birders to identify trees at a distance. This skill is particularly useful for people who bird in groups since it is easier to get people on a bird if you can say that it is in a walnut tree rather than "that tree over there." However, knowing more about trees should also interest birders because many birds are closely tied to particular tree species. Kirtland's Warblers may be the most prominent example, as they are entirely dependent on Jack Pines of a certain age.
This guide's organization will look familiar to those who have used The Sibley Guide to Birds. A lengthy introduction instructs the reader on what features of a tree are the most important for identifying it. This section also introduces common botanical terms and variations in the shapes of leaves and fruit. The subsequent species accounts are ordered by family. Common tree species receive a full page or more, while less common species or nonnative cultivars are treated in half a page or less. It is similar to Sibley's bird guide in concept as well as organization. Rather than make users start with a botanical key, Sibley wants readers to flip through the guide until they find the right tree species.
Identification notes and illustrations are placed together, so there is no need to flip back and forth between plates and text. (I much prefer this layout, as I noted in a previous review!) Most accounts show painted images of the bark, leaves (both upper- and undersides), fruit, and twigs. Many show the shape of a fully-grown tree, and some of the more common species show both summer and fall leaf colors. Each species account also includes a range map and notes on favorable habitats. It is interesting to note that the species and family accounts in this guide seem to have much more text than the accounts in The Sibley Guide to Birds. While it never bothered me, I frequently have heard complaints from other birders that species accounts in Sibley's bird guide are too laconic.
Even if I was not entirely successful, my trial run convinced me that this is the best of the tree guides that I have used so far. The illustrations are helpful for identifying unfamiliar trees, and they are of the high quality that I have come to expect from David Sibley's work. The text is helpful not just for identifying trees but also for learning about their natural history and conservation. I think that The Sibley Guide to Trees will be a very useful guide for birders and other naturalists.
David Allen Sibley, The Sibley Guide to Birds. New York, Knopf, 2009. Pp. xxxviii, 426; color illustrations, maps, checklist, index. $39.95 paper.
Birder's World recently interviewed David Sibley about his new tree guide: Part 1; Part 2; Part 3. David Sibley is asking readers who find errors to let him know.