Final answer:
Contour feathers on a bird's body reduce drag by creating a smooth aerodynamic surface that enables efficient flight.
Step-by-step explanation:
The type of feather that helps to reduce drag produced by wind resistance during flight is the contour feather. Contour feathers are found on the bird's body, and they function to create a smooth, aerodynamic surface which allows air to move swiftly over the bird's body. This prevents turbulence and results in ideal aerodynamic conditions for efficient flight, thus reducing form drag. In contrast, primary feathers at the wing tip provide thrust, and secondary feathers closer to the body provide lift. While down feathers are excellent for insulation, they do not play a role in reducing drag during flight.
Contour feathers help to reduce drag produced by wind resistance during flight. They are found on the body of the bird and create a smooth, aerodynamic surface, allowing air to move swiftly over the bird's body and preventing turbulence. This creates ideal aerodynamic conditions for efficient flight.