Question

why do birds have nucleated RBC's?​

Answer 1

There are two reasons. But first a little terminology. Blood cells with nuclei are nucleated. Blood cells without nuclei are enucleated.

One, mammals are younger in natural history than birds. Before mammals, nucleated blood cells were the norm. Mammals evolved enucleated blood cells to use oxygen more efficiently.

Two, birds have a different respiratory system that lets them transport oxygen efficiently without needing enucleated blood cells. They have "flow-through" respiration that lets air move continuously through the body. Mammals have alveoli that are like a dead-end for moving air.

Answer 2

$<b><marquee behavior= "alternate">Heya!! </marquee>$

There are two reasons. But first a little terminology. Blood cells with nuclei are nucleated. Blood cells without nuclei are enucleated.

One, mammals are younger in natural history than birds. Before mammals, nucleated blood cells were the norm. Mammals evolved enucleated blood cells to use oxygen more efficiently.

Two, birds have a different respiratory system that lets them transport oxygen efficiently without needing enucleated blood cells. They have "flow-through" respiration that lets air move continuously through the body. Mammals have alveoli that are like a dead-end for moving air

$<marquee behavior=move bgcolor=pink> <h1> Follow me ❤</h1></marquee>$