If birds' bones are hollow, where do they get new red blood cells?

Question

I think birds' bones are hollow so that they are lighter and able to fly; in humans, our bone marrow makes our red blood cells. If bone marrow doesn't make blood cells in birds, then where are they made in birds?

Answer 1

Birds do have bone marrow. It's just that the space taken up by the marrow is smaller than that in mammals as birds also have large pockets of air in their bones.

Answer 2

There is bone marrow in the bird's bones just like yours. Your bones have much more calcium making them stronger.