They can stay warm because they have a thick layer of down under the outer feathers and a layer of blubber.
(They; can stay; warm; because they have a thick layer of down under the outer feathers and a layer of blubber) (they; have; a thick layer of)
They they
can stay have
warm because they have a thick layer of down under the outer feathers and a layer of blubber
a thick layer of