Brace yourselves, birders: here comes the sixth edition of the National Geographic Field Guide to the Birds of North America. I haven’t laid hands on a copy myself, but advance word has it that the new version is 71 pages longer than the fifth edition, with 23 additional species accounts (mostly extralimital vagrants) and 300 new illustrations. Oh yes, and range maps for subspecies. That’s going to cause a lot of trouble.
At $27.95, most likely I’ll buy it when it hits the stores. I’ll probably also buy the rumored revision of David Sibley’s canonical bird guide; no details on that one yet. But I will do so with lowered expectations.
The thing about field guides is that they offer a handle on the natural world. They tell you that you can, after all, tell a hawk from a handsaw. The field marks, the behavioral cues, the breeding and wintering ranges and migration routes: they’re all in the book. All you have to do is pay attention.
That’s a really seductive promise. I’m a sucker for field guides; I own guides to the wildlife and plants of places I’m never going to visit. Butterflies of the West Indies? Trees of New Zealand? Birds of Botswana? Used copies too—how can I resist? And I’m sure I can cram them into the bookshelves somehow.
But very few of these books fulfill that promise. For some organisms, field sightings just aren’t enough. To use a mushroom guide effectively, you need to be able to make spore prints—especially if you plan to eat what you find. Some reptiles can only be identified to species by counting scales. Butterfly identification sometimes requires examining male genitalia under the microscope (“pulling tails,” as Nabokov put it.) Plant field guides often need to be supplemented by one of those 20-pound tomes with dichotomous keys, like the Jepson Manual, where identification hinges on a plant part you don’t have.
The range maps in field guides can also be misleading. UC Davis
entomologist Arthur Shapiro wrote an article a few years ago called “Your Field Guide is Lying to You,” and he has a point. Distributions of organisms, especially the less mobile ones, tend to be patchy and discontinuous. You’re not going to find your target species just anywhere in the color-coded portion of the map.
Even with bird guides, the grandfathers of the genre, there are limits. Some birds are always going to elude precise identification. There will always be something that flies into a fog bank or drops down into a thicket before you can make out the critical field marks. There will always be anomalies: hybrids, strange pigmentation patterns or lack thereof.
And some field marks are subtle in the extreme. Any birder who confidently identifies Empidonax flycatchers in the fall is kidding him/herself. The taxonomists are just making it worse. As genetic studies redefine species boundaries, we’re going to wind up with more and more near-identical but countable species. Not just species pairs: species clusters. What if there really are ten valid
North American crossbill species that can’t be separated by appearance (they all look alike) or range (they’re nomadic), but only by voice? What do you do with a silent crossbill? That way lies madness.
I am not trying to dissuade anyone from buying the new National Geographic guide, or the new Sibley, or whatever else is in the pipeline. Buy them, peruse them during the rainy winter, stuff them in your backpack. Just don’t turn to them for certainty.