Purpose:

• Attracting mates and ornamental function.

• Use in the regulation system (cooling).

• Vary in size and shape among avian species as well as among strains of chickens.

• Size and color are also dependent on sex hormones.

• Composed of keratin

• They shield the skin from damage and insulate from extreme temperatures.

Mouth

• • No lips or teeth

Beak

• • Crush, tear, or hold food

Tongue

• • Narrow & often triangular

  • Few taste buds

  • Numerous touch receptors- distinguish food by the feel of it

• Large vein under the wing.

• Lies in the depression between the biceps brachialis and triceps humeralis muscles.

• Used for blood collection.

• A large bi-lobe sebaceous gland

• Dorsally at the base of the tail

• Secretes oil, which can be distributed throughout feathers of birds by preening behavior.