Final answer:
In birds, an absolute reticulocyte count is not useful in assessing the bone marrow response to anemia.
Step-by-step explanation:
In mammals, an absolute reticulocyte count is not useful in assessing the bone marrow response to anemia in birds. Unlike mammalian red blood cells, bird red blood cells do not have nuclei, which is one of the factors that makes the reticulocyte count not applicable in assessing their bone marrow response to anemia.