Contour feathers

Contour feathers are the external feathers that cover the body, wings, and tail of a bird. They help in streamlining the bird's body for flight, provide insulation, and are involved in coloration and display. Contour feathers are one of the most visible types of feathers, distinguishing birds from other animals.

Structure

Contour feathers have a central shaft, or rachis, which splits into a vane on either side. The vane is made up of numerous barbs, which further divide into barbules. These barbules have hooklets or barbicels that interlock, giving the feather its smooth and streamlined surface. This structure is crucial for the aerodynamic properties of the feathers, allowing for efficient flight.

Function

The primary function of contour feathers is to reduce air resistance during flight. Their streamlined shape allows air to flow smoothly over the bird's body, reducing drag. Additionally, these feathers play a significant role in thermoregulation, helping to keep the bird warm in cold conditions and cool in hot conditions by adjusting the position of the feathers to regulate heat loss.

Contour feathers are also vital for camouflage and signaling. The coloration and pattern of these feathers can help a bird blend into its environment or, conversely, stand out to signal to others of its species. This is particularly important during mating seasons when birds display their plumage to attract mates.

Types

There are several types of contour feathers, each serving a specific function:

• Body feathers cover the main part of the body, providing insulation and aiding in camouflage.
• Flight feathers are located on the wings and tail and are specialized for flight. These include the primary feathers, secondary feathers, and tertiary feathers, each contributing to different aspects of flight control and efficiency.
• Covert feathers are smaller feathers that lie over the bases of flight feathers, smoothing airflow over the wings and tail.

Maintenance

Birds spend a significant amount of time maintaining their contour feathers through preening. Preening involves using the beak to clean, reposition, and apply oil from the uropygial gland to the feathers. This oil helps keep the feathers flexible, waterproof, and in good condition for flight.

Evolution

Contour feathers are believed to have evolved from the scales of reptiles, with fossil evidence suggesting their presence in some dinosaurs. This evolutionary adaptation has been crucial in the success of birds, allowing for flight, which is a key factor in the survival and dispersion of many bird species.

See Also

• Feather
• Bird flight
• Plumage
• Uropygial gland