catweb: A Web-based bird photo catalog

The term ancestor is used here in the sense of a tree structure. The ancestors of a node include its parent node (if any), its parent's parent, its parent's parent's parent, and so on all the way to the root of a tree.

In reference to the tree of taxa that represent a taxonomic arrangement, the ancestors of a taxon are the higher-level taxa that contain that taxon.

A taxon is said to be contained in all its ancestor taxa (see Section 2.1, “Ancestor”. For example, the species Falco sparverius is contained in genus Falco, subfamily Falconinae, family Falconidae, order Falconiformes, and class Aves.

The term descendant is used in the sense of a tree structure: the descendants of a node in a tree are the children of the given node, the children of the children, and so forth down to the leaf nodes of each branch.

Each English name describing a form of bird is referred to the one specific taxon that is the smallest unit of classification to which the image clearly refers. In the great majority of cases, a photo is referred to a species: for example, the Crissal Thrasher is referred to Toxostoma crissale.

However, there are both finer and coarser distinctions. Blue Goose is a color morph of the species Snow Goose; the base taxonomy system calls such groups “subspecific forms,” meaning that they are finer than species level; technically, “subspecies” has a narrower meaning in taxonomy.

There are many cases where the image is referred to a higher-ranked taxon than species. For example, “owl sp.” implies no finer level of detail than Order Strigiformes, the order of owls. Also, Consider hybrids such as Mallard (Anas platyrhynchos) × Gadwall (Anas strepera). This form is referred to genus Anas.

The inverted form of an English bird name means that the generic part comes first, followed by a comma and the specific part. For example, “American Robin” becomes “Robin, American.”

For this application, we define the generic part of a name as the last word or hyphenated group of words. If there is only one name or hyphenated group, the inverted name is the same as the uninverted name. Examples: