Source: Extra Practice
Birds often fluff up their feathers in cold weather. How does this action help them stay warm?
Options
Option A
It increases the bird's surface area to absorb more heat.
Option B
It helps them radiate more heat to the surroundings.
Option C is correct
It traps a layer of air, which is a poor conductor of heat.
Option D
It increases blood flow to the skin, making them warmer.
Explanation
When birds fluff feathers, they trap a layer of air close to their body. Air is an excellent insulator and a poor conductor of heat. This trapped air layer reduces heat loss from the bird's body to the cold surroundings via conduction and convection, thus helping the bird stay warm. Other options would increase heat loss.