Sirin, the Bird of Sorrow, and her counterpart, Alkonost, the Bird of Joy. Victor Vasnetsov (1896), Sirin and Alkonost.
According to the Encyclopedia of Spirits, Alkonost was a bird of paradise and a spirit of the wind with the power to raise enormous storms. Originally she lived in the Russian “otherworld island” of Buyan, but transferred to the Garden of Eden where she served as God’s personal messenger on Earth, singing beautiful melodies to wandering, wayward souls. Her songs prophesied a happy ever-life in Paradise, boosting the spirits of mortal men.
Over time, Alkonost’s sister kindred-spirit, Sirin, became classified as a harbinger of death to mortal men, while the angelic Alkonost promised an eternal life in Paradise.