Specific Characteristic of Aves

FEATHER

Have you ever seen a bird without feathers?

Bird feathers are amazingly complex. Each feather is made from the protein Keratin. While keratin also makes up snake and lizard scales, it is a slightly different compound in birds. The three main types of feathers are the filoplumes (sensory feathers), the contour feathers, and the down feathers (insulation).

While most feathers share a common overall structure, there are several different kinds of feathers adopted for specialized roles. Changes in feather structure provide the adaptations necessary for feathers to be used in many different ways. Feathers also support the behavior of the bird within its environment and its lifestyle. Feathers that support the soaring flight of an eagle have a much different role than the feathers that protect an American Dipper, which spends much of its time in fast-flowing streams.

Feather topography:

A typical wing feather consists of a central, stiff shaft with the softer vanes on each side. The leading edge of the feather during flight is called the outer vane. The opposite vane is wider than the outer vane and is referred to as the inner vane. In greater detail, feathers are broken down into the following structural elements.
  

Central shaft:

The central shaft of a feather is divided into two regions. The calamus is the part of the shaft closest to the bird's body. It is hollow and does not contain any vanes. The distal end of the central shaft is referred to as the rachis. The rachis is solid and is defined as the area to which vanes are attached.

Vanes:
The vanes extend from each side of the feather. A series of parallel branches called barbs make up the vane. Extending from the barbs are a series of short branchlets called barbules. Tiny hooklets tie the barbules, and ultimately the barbs, together. This somewhat complex arrangement creates the strong but light structure of the feather.

                      

BEAK

Birds eat many different types of foods. It may depend upon their environment and what’s available for them to eat. It could even depend upon their body and beak structure and how they are able to get the food. Bird beaks (or “bills” as scientists call them) have adapted over the years to help the bird survive in whatever environment they are in.

SHAPE	TYPE	ADAPTATION
	Cracker	Seed eaters like sparrows and cardinals have short, thick conical bills for cracking seed.
	Shredder	Birds of prey like hawks and owls have sharp, curved bills for tearing meat.
	Chisel	Woodpeckers have bills that are long and chisel-like for boring into wood to eat insects.
	Probe	Hummingbird bills are long and slender for probing flowers for nectar.
	Strainer	Some ducks have long, flat bills that strain small plants and animals from the water.
	Spear	Birds like herons and kingfishers have spear-like bills adapted for fishing.
	Tweezer	Insect eaters like warblers have thin, pointed bills.
	Swiss Army Knife	Crows have a multi-purpose bill that allows them to eat fruit, seeds, insects, fish, and other animals.