It happened to most people who are now bird watchers. They saw some bird that was so colorful, or so unusually-shaped, or behaved in such an interesting manner that they decided to find out more about it. They picked up a field guide to birds...
If they are like most people they couldn't immediately find the bird. The birds seemed to be arranged randomly throughout the field guide. Eventually, in frustration, they began a page-by-page picture search trying to match what they saw with the bewildering array of birds in the field guide.
Most field guides are arranged in taxonomic order, with birds presumed to be closely related next to each other. The trouble is, birds may be closely related and not look like each other. Other birds, not closely related, can have the same basic appearance. The sequence of birds on a checklist or in a taxonomically-oriented field guide is necessarily linear, but bird relationships are web-like. And scientists are constantly rearranging the sequence!
But, if the purpose of a field guide is to truly help people identify a bird they have seen, shouldn't birds that look alike appear together in the book, regardless of constantly-shifting presumed relationships?
For instance, the Great Blue Heron (below) is known by birders and non-birders throughout North America.
Of course, many non-birders call the Great Blue Heron a "crane" or "blue crane." But herons are not cranes. They are not closely related, and are not found near each other in most field guides.
But they do share long neck and long legs in common. They are both similar in bill shape, size, and coloration. They may even be found in the same locations at the same time. Why shouldn't the Sandhill Crane (below) be placed in the field guide next to the heron?
The crane is, however, very closely related to the American Coot (below), at least, internally. But they don't look that much alike on the outside. The coot looks more like a duck than a heron. But in the field guides the coot is next to the crane, not to ducks or other waterbirds.
In fact, the coot looks quite a bit like the Pied-billed Grebe (below). But are the coot and grebe close together in the field guide? You know the answer. They are nowhere near each other!
Part Two will discuss proposed arrangements to address this problem.