The Simurgh (also known as the Simorgh) is a mythical bird-like creature who happens to appear in the Shahnameh (the tenth century Persian epic poem starring Rostam, mentioned in the last post). Wikipedia mentions a tenuous link between simurgh and eagles, which is enough to inspire this version of Eagle Sunday.
We already know Rostam, the tough man hero with the scary horse. The Simurgh appears much earlier in Rostam's story and is instrumental in our hero's birth. Rostam's father Zal is born with white hair - apparently an evil omen - and is therefore abandoned by his parents. Baby Zal is left in the mountains to die, but is rescued by a Simurgh who raises the baby with her own young. When Zal has grown up, and the time comes for him to be reclaimed by his family, the Simurgh gives him two magical feathers as a parting gift.
Zal later uses the feathers to call upon the Simurgh for help. Rostam's mother struggles to give birth to the fearsome and enormously large hero, and it looks like both mother and baby will die. When Zal throws a feather into the fire, the Simurgh appears:
... and the bird appeared, ready to do his bidding, like pearls raining down from a dark cloud; I say pearls, but it was peace to the soul that she brought.
(from Rostam: Tales of Love and War from the Shanameh by Abolqasem Ferdowsi, translated by Dick Davis)
The Simurgh calmly provides instructions for what looks suspiciously like a tenth century caesarean section, and Rostam and his mother are saved. Hooray!