Feathers help birds fly and provide insulation.
Some birds are flightless birds.
Feathers provide insulation for the flightless. .
Why do the flightless have feathers?

(1) layers of fat
(2) Sublimation
(3) it needs them
(4) warm-blooded
(5) Air conditioning
(6) Radiation
(7) Insulation
(8) protect them