The bill: an overview

The bill, or beak, of a bird assists them in eating. Different bills are best used for different kinds of foods and feeding methods. Specific scientific families of birds eat similar foods and have similarly shaped bills. Thus, the shape of the bill is key in beginning to identify a bird correctly.

For instance, Hutton's Vireo is a small green bird with an eyering and two wingbars. In plumage, habitats, and some behaviors, it is very similar to some Empidonax flycatchers, but the bills are quite different!

Again, beginners are sometimes confused by their first Spotted Towhee, thinking it must be related to the somewhat similar-looking American Robin. But one look at the bill and a birder in-the-know will quickly see that the bills are quite different, with the robin having a generalist bill and the towhee a seed eating bill.

Gulls and terns are similar and in the same family. However, the bills of terns are sharp-pointed, the bills of gulls are strongly hooked.

An American Goldfinch--bright yellow with a black cap--has a small conical seed eating bill. Carefully observing that, one would not confuse it with the insect eating bill of the Wilson's Warbler, also bright yellow with a black cap.

Every bill of a bird can be described using standard terminology. A birder should attempt to learn these terms and the correct meaning. In this regard a textbook on ornithology would be of great use.

Characters of the bill:
Long
Short
Hooked
Crossed
Compressed
Depressed
Stout
Terete
Straight
Recurved
Decurved
Bent
Swollen
Acute
Chisel-like
Toothed
Serrate
Gibbous
Spatulate
Notched
Conical
Lamellate

In addition, some birds have other features of the bill such as gular sacs, rictal bristles, nostrils in a fleshy cere or nostrils in a tube.

Here is a web site that may be helpful:
Bird External Anatomy from an ornithology course at Eastern Kentucky University.

Future posts will discuss bill shapes more specifically.
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Artwork of bird beaks used under the Creative Commons Attribution-ShareAlike license (CC-BY-SA). Author: L. Shyamal.

Orbital rings

Western Gull, Beaverton, Oregon, 15 November 2011 by Greg Gillson.

 

On adult gulls the skin around the eye is often colored brightly. This can be a clue to identification. The hue and intensity can change with breeding condition or other factors.

Typical adult Western Gulls have yellow-orange orbital rings.

The wing

Black-footed Albatross, off Newport, Oregon, 15 May 2011 by Greg Gillson.

 

The wing of birds is analogous to the arm of humans. This is most evident on longer-winged birds like the albatross above. They have a shoulder, elbow, and wrist. They have similar bones--a humerus in the upper arm, and radius and ulna in the lower arm. The hand, or manus, is composed of several fused hand and finger bones--it's more like one long finger.

Primaries are attached to the hand. Primaries are numbered from inner to outer, P1 to P10 in the photo above. Birds have from 8-11 primaries, depending upon species. In general, most non-Passerines have 10 primaries; most Passerines have 9 primaries.

Secondaries are attached to the ulna. Secondaries are numbered from outer to inner. Birds have a variable number of secondaries depending upon the length of the wing.

Primaries and secondaries are called the flight feathers of the wing, or remiges. (The tail with its retrices, are also considered "flight feathers.")

True tertials or tertiaries are feathers attached to the humerus, the bone from shoulder to elbow. They are not considered to be flight feathers, or remiges. Very long-winged birds have more tertials than shorter winged birds. Some bird families, including shorebirds and gulls, have modified tertials that are longer and distinctively marked.

In many smaller birds the humerus is so short as to be lacking separate tertial feathers. However, sometimes the inner 3 secondary feathers on passerines are called tertials when differently shaped or colored than the other secondary feathers.

Black-footed Albatrosses have 10 primaries, 25-29 secondaries, and numerous tertiaries or tertials.

 

Western Gull, Beaverton, Oregon, 17 February 2009 by Greg Gillson.

 

Most gulls have 10 primaries and 24 secondaries. They also have some true tertial feathers.

 

Vaux's Swift, Forest Grove, Oregon, 22 September 2009 by Greg Gillson.

 

Vaux's Swifts have 10 primaries, but only 6 (or 8, if you count very tiny) secondaries.

The very different lengths of the parts of the arm cause different styles of flapping.

Seven methods of identifying birds: #2: Structure

This post continues the discussion of the Seven methods of identifying birds.
[Answer to Quiz 1: Western Tanager]

Structure:

The end plates of the Peterson field guides are silhouettes: "Roadside Silhouettes" and "Shore Silhouettes." These show size and shape among most of the different orders of common birds.

The section "How to Watch Birds" in Peterson's field guides gives an excellent primer on structure of bill, tail, and wing. Don't skip the introductory material in field guides!

Earlier this spring I wrote a post, Dabbling duck silhouette quiz, which uses shape alone to identify female ducks.

Quiz) This medium to large slender bird has extremely long legs, very long neck, and long, thin, upturned bill.

Next: Feather-by-feather analysis