This is reffering to a bird known as the Phoenix, and death was not placed upon it, because it had not tasted from the tree of Knowledge [at the sin of Adam and Eve]. After 1,000 years it renews, and goes into its youth.
With regard to the lion, a fever sustained it, since when it suffered from a fever, it did not need to eat; as Rav said: For no fewer than six days and no more than twelve days, fever sustains a person; he need not eat and is sustained from his own fats. Shem continued: With regard to the phoenix [avarshina], my father found it lying in its compartment on the side of the ark. He said to the bird: Do you not want food? The bird said to him: I saw that you were busy, and I said I would not trouble you by requesting food. Noah said to the bird: May it be God’s will that you shall not die, and through that bird the verse was fulfilled, as it is stated: “And I said, I shall die in my nest, and I shall multiply my days as the phoenix” (Job 29:18).